Download kinetra - Medtronic

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KINETRA®
Dual Program Neurostimulator for Deep Brain
Stimulation
Technical Manual
Rx Only
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KINETRA®
Technical Manual
Model 7428
220822001
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The following are trademarks of Medtronic:
Access™, Activa®, DBS™, Itrel®, Kinetra®, Medtronic®,
MemoryMod®, SoftStart™, N’Vision™, and Soletra™.
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Table of Contents
Overview of Manual 5
System Description 6
Indications 6
Contraindications 7
Warnings 8
Precautions 10
Physician Training 10
Storage and Sterilization 10
System and Therapy 10
Implantation/Explantation 12
Electromagnetic Interference (EMI) 14
Medical Environment 15
Home or Occupational Environment 16
Clinical Studies and Adverse Events 18
Individualization of Treatment 18
Resterilization 18
Directions for Use 20
Neurostimulator Implantation or Replacement 20
Tunneling to the Neurostimulator Site 21
Making the Lead-Extension Connection 21
Making the Extension-Neurostimulator Connection 21
Explant Disposition 31
Environmental Problems 31
Handling and Storage 34
Patient Registration 34
Physician Training Information 35
Patient Counseling Information 36
Theft Detectors and Screening Devices 36
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Component Manipulation by Patient 37
Kinetra Patient Eligibility 38
Rate Control 38
Screening for Patient Eligibility 38
Detailed Device Description 40
General Description 40
Postoperative Patient Management 45
Programming Stimulation Parameters 49
Electrode Programming Configurations 53
Test Stimulation 56
Specifications and Features 56
How Supplied 63
Appendix A: Battery Longevity Reference Information
Tips for Maximizing Battery Life 64
Estimating Battery Life Prior to Neurostimulator
Internalization 64
Battery Longevity Worksheet 68
Appendix B: MRI and Activa Therapy 74
Introduction 74
General Information on MRI 77
MRI Interactions with Implanted Activa Systems 78
MRI Procedure 79
Glossary 85
Special Notice 86
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Overview of Manual
Overview of Manual
This manual provides information on the Kinetra neurostimulator, a
component of the Activa System for deep brain stimulation. The
manual describes some items to discuss with your patient, and
explains how to register the patient’s device. You will also find
instructions for handling, storing, implanting, replacing, and
explanting the neurostimulator. General resterilization guidelines are
also provided for the new neurostimulator.
The manual is divided into the following sections:
■
System Description
■
Indications
■
Contraindications
■
Warnings
■
Precautions
■
Adverse Events
■
Clinical Studies
■
Individualization of Treatment
■
Directions for Use
■
Physician Training Information
■
Patient Counseling Information
■
Detailed Device Description
■
How Supplied
■
References
■
Glossary
■
Special Notice
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System Description
System Description
The Medtronic Activa System is an implantable, multiprogrammable
system that delivers electrical stimulation to selected areas of the
brain.
The dual program Model 7428 Kinetra Neurostimulator generates
electrical signals that are transmitted to the brain. These signals are
delivered from the neurostimulator to the brain via the Model 7482
DBS Extension and either the Model 3387 DBS Lead or the Model
3389 DBS Lead. These components comprise the implantable
portion of the Activa System.
The neurostimulator consists of electronic circuitry and a battery,
which are hermetically sealed in a titanium case. The operation of the
neurostimulator is supported by a clinician programmer, a therapy
controller, and a control magnet.
For a complete list of model numbers and components compatible
with the Kinetra Neurostimulator, see the Activa System Components
Sheet packaged with this manual in the neurostimulator shelf box.
Indications1
Bilateral stimulation of the internal globus pallidus (GPi) or the
subthalamic nucleus (STN) using Medtronic Activa Parkinson’s
Control Therapy is indicated for adjunctive therapy in reducing some
of the symptoms of advanced, levodopa-responsive Parkinson’s
disease that are not adequately controlled with medication.
1
The dual program Kinetra Model 7428 neurostimulator is not approved for Tremor
Control Therapy since only unilateral stimulation is aprpoved for Tremor Control
Therapy.
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Contraindications
Contraindications
Implantation of an Activa Brain Stimulation System is contraindicated
for:
■
Patients exposed to diathermy. Do not use shortwave
diathermy, microwave diathermy or therapeutic ultrasound
diathermy (all now referred to as diathermy) on patients
implanted with a neurostimulation system. Energy from
diathermy can be transferred through the implanted system
and can cause tissue damage at the location of the implanted
electrodes, resulting in severe injury or death.
Diathermy is further prohibited because it can also damage the
neurostimulation system components resulting in loss of
therapy, requiring additional surgery for system explantation
and replacement. Injury or damage can occur during
diathermy treatment whether the neurostimulation system is
turned “on” or “off.” Advise your patients to inform all their
health care professionals that they should not be exposed to
diathermy treatment.
■
Patients who will be exposed to Magnetic Resonance Imaging
(MRI) using a full body transmit radio-frequency (RF) coil, a
receive-only head coil, or a head transmit coil that extends over
the chest area. Performing MRI with this equipment can cause
tissue lesions from component heating, especially at the lead
electrodes, resulting in serious and permanent injury including
coma, paralysis or death. Refer to “Appendix B: MRI and
Activa Therapy” on page 74 for comprehensive safety
information and instructions.
■
Patients for whom test stimulation is unsuccessful.
■
Patients who are unable to properly operate the brain
stimulator.
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Warnings
Warnings
Coagulopathies – Use extreme care with lead implantation in
patients with a heightened risk of intracranial hemorrhage.
Physicians should consider underlying factors, such as previous
neurological injury, or prescribed medications (anticoagulants), that
may predispose a patient to the risk of bleeding.
Avoid Excessive Stimulation – There is a potential risk of brain
tissue damage for stimulation parameter settings of high amplitudes
and wide pulse widths.
The Activa System is capable of parameter settings out of the range
of those used in the clinical studies. Suppression of symptoms
should occur at amplitudes of 1 to 3.5 V, pulse widths of 60 to
120 µsec, and rates of 130 to 185 Hz. Higher amplitudes and pulse
widths may indicate a system problem or less than optimal lead
placement. Parameter values exceeding the recommended output
settings should only be programmed with due consideration of the
warnings concerning charge densities described in “Programming
Stimulation Parameters” on page 49.
If programming of stimulation parameters exceeds charge density
limits, the following programmer warning appears: WARNING:
CHARGE DENSITY MAY BE HIGH ENOUGH TO CAUSE TISSUE
DAMAGE.
The use of rates less than 30 pps may “drive” tremor, i.e., cause it to
occur at the same frequency as the programmed frequency. For this
reason, rates should not be programmed below 30 pps.
Case Damage – If the neurostimulator case is ruptured or pierced
after implant due to outside forces, severe burns could result from
exposure to battery chemicals.
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Warnings
Placement of Lead-Extension Connector in Neck – Do not place
the lead-extension connector in the soft tissues of the neck.
Placement in this location has been associated with an increased
incidence of lead fracture.
Theft Detectors and Screening Devices – Theft detectors found in
retail stores, public libraries, etc., and airport/security screening
devices may cause the stimulation power source of an implantable
neurostimulation system to switch On or Off1. It is also possible that
sensitive patients, or those with low stimulation thresholds, may
experience a momentary increase in their perceived stimulation. For
other indications, higher levels of stimulation have been described as
uncomfortable (“jolting” or “shocking”) by some patients as they pass
through these devices. Refer to “Patient Counseling Information” on
page 36 for more information.
Replacement Procedure – Do not replace two Soletra Model 7426
Neurostimulators with one Kinetra Model 7428 Neurostimulator
unless retunneling is performed so both lead-extensions are on the
same side of the body. Otherwise, the “looped” configuration formed
by the lead-extensions increases the potential for electromagnetic
interference (EMI) effects.
Magnetic Resonance Imaging – Do not conduct an MRI
examination on a patient with any implanted Activa System
component until you read and fully understand all MRI information in
this manual. Do not conduct an MRI examination at parameters other
than those described in this guideline. Failure to follow all warnings
and guidelines related to MRI can result in serious and permanent
injury including coma, paralysis, or death. Refer to “Appendix B: MRI
and Activa Therapy” on page 74 for comprehensive safety
information and instructions.
1
Unexpected On/Off switching of the Kinetra Model 7428 Neurostimulator, as described
throughout the Warnings and Precautions sections of this manual, may be avoided by
disabling the magnet control circuit with the clinician programmer software. If the
magnet control circuit is disabled, patients will require a Model 7436 Therapy Controller
to turn their therapy On or Off. Refer to “Control Magnet” on page 44.
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Precautions
Precautions
Physician Training
Implanting Physicians – Implanting physicians should be
experienced in stereotactic and functional neurosurgery. Refer to
“Physician Training Information” on page 35 in this manual for further
information.
Prescribing Physicians – Prescribing physicians should be
experienced in the diagnosis and treatment of movement disorders
and should be familiar with the use of the Activa System.
Storage and Sterilization
Resterilization Considerations – Refer to “Resterilization” on
page 18 for further information.
Storage Temperature – Store the Model 7428 Neurostimulator
between 0° F (-18° C) and 131° F (55° C). Temperatures outside this
range can damage components.
System and Therapy
Battery Longevity and Brain Target Selection – Stimulation
settings for systems implanted in the internal Globus Pallidus (GPi)
may be higher than stimulation settings for systems implanted in the
Subthalmic Nucleus (STN). Consequently, systems implanted in the
GPi may have shorter battery life than systems implanted in the STN.
Component Failures – The Activa System may unexpectedly cease
to function due to battery depletion or other causes. These events,
which can include electrical short or open circuits, conductor (wire)
fracture, and insulation breaches, cannot be predicted. The patient’s
disease symptoms will return if the device ceases to function.
Components – The use of non-Medtronic components with this
system may result in damage to Medtronic components, loss of
stimulation, or patient injury.
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Precautions
Inadvertent Programming – If more than one neurostimulator is
implanted, then the potential for unintentional programming changes
to the other neurostimulator exists. If two neurostimulators are
implanted, they must be implanted at least 8 inches apart to minimize
interference. Verify final programmed parameters by reviewing both
devices at the conclusion of any programming session.
Lead Materials – The polyurethane tubing of the lead may release
neurotoxic or carcinogenic compounds. Data are insufficient to
assess the likelihood of these effects occurring in patients who
receive the device.
Long-Term Safety and Effectiveness of Activa Therapy – The
long-term safety and effectiveness of Activa Therapy has not been
established.
Use in Specific Populations – The safety and effectiveness of this
therapy has not been established for the following:
■
Patients with neurological disease origins other than idiopathic
Parkinson’s disease
■
Patients with a previous surgical ablation procedure
■
Patients who are pregnant
■
Patients under the age of 18 years
■
Patients over the age of 75 years
■
Patients with dementia
■
Patients with coagulopathies
■
Patients with moderate to severe depression
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Precautions
Implantation/Explantation
Body Fluids – Do not resterilize any system component after
exposure to body fluids.
Component Disposal – If explanting an Activa System component,
please remember the following guidelines:
■
Do not incinerate or cremate the neurostimulator; explosion
can result if a neurostimulator is subjected to incineration or
cremation temperatures.
■
Return all explanted components to Medtronic for analysis and
safe disposal.
Connections – Wipe off any body fluids on the extension or lead
contacts or connector before connecting. Contamination of
connections can cause intermittent stimulation or shorts in the
neurostimulation circuit.
Connector Block Setscrews – Limit counter-clockwise rotations of
neurostimulator setscrews. Rotate enough to provide an
unobstructed pathway for the extension connector pins. Too many
counter-clockwise rotations may disengage the setscrew from the
connector block.
Etched Identification – Place the neurostimulator away from bony
structures and with the etched identification side facing outward,
away from muscle tissue to minimize pain at the neurostimulator site.
This also helps to minimize the possibility of skeletal muscle
stimulation, which may be perceived by the patient as twitching or
burning.
Excess Extension Wire – Do not place any excess extension wire
on top of the neurostimulator’s front side (printed side). Wrap any
excess extension wire around the perimeter (Figure 1). This avoids
any increase in subcutaneous pocket depth, helps minimize potential
damage during neurostimulator replacement surgery, and helps
minimize potential kinking of the extension wire.
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Precautions
Figure 1. Wrap excess wire around the perimeter of the neurostimulator.
Handling Components – Handle the implanted components of this
system with extreme care. These components may be nicked, cut, or
damaged by excessive traction or sharp instruments and may require
surgical replacement.
■
Do not bend, kink, or stretch the lead body whether or not the
stylet is in place. Do not bend or kink the tungsten stylet.
■
Do not tie a suture directly to the extension or lead body. Use
the burr hole cap and ring provided by Medtronic to secure the
lead in place.
■
When handling the lead with forceps, use only a rubber-tipped
bayonet forceps.
Hex Wrench – Do not overtighten setscrews when using the hex
wrench. Excessive torque on setscrews may damage lead contacts.
Verify that the sealing grommet has closed on the neurostimulator.
Implant Considerations – Do not implant a component of the
system when:
■
The storage package has been pierced or altered; or if the
component shows signs of damage; or
■
The “Use By” date has expired, because this can adversely
affect storage package sterility.
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Precautions
Multiple Implants – The long-term safety associated with leads left
in place without use, replacement of leads, multiple implants into the
target structure, and lead explant is unknown.
Percutaneous Extension Setscrew Connector – If resistance is
still felt when removing lead from the percutaneous extension
setscrew connector, loosen the setscrews slightly to ensure that they
clear the lead contacts. Avoid disengaging the setscrews. Inspect the
lead contacts for damage (flattening or stretching of the lead) if
resistance was felt prior to removal.
Percutaneous Extension Severing – When severing the
percutaneous extension, use gentle traction on the extension to avoid
dislodging the lead.
Percutaneous Extension Suture Removal – Do not cut near the
lead when removing sutures from the percutaneous extension.
Cutting the lead’s insulation can result in loss of stimulation and the
lead’s failure.
Sutures – Do not draw the suture too tightly because damage may
occur to the connector boot or to the extension or lead.
Torque Wrench – To prevent undertightening the neurostimulator
setscrews, do not use the torque wrench from the extension kit.
Undertightening may result in insufficient electrical contact within the
connector block, which may cause intermittent stimulation.
Electromagnetic Interference (EMI)
Electromagnetic interference is a field (electrical, magnetic or a
combination of both) that is generated by various medical or
environmental devices. These medical and environmental (home,
occupational, and other) devices may generate enough interference
to change the parameters of a neurostimulator; turn a
neurostimulator off and on, or cause a neurostimulator to surge,
shock, or jolt the patient.
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Precautions
In addition, it is possible for the extension, lead, or both to “pick up”
electromagnetic interference and deliver an excess voltage, which
can in turn deliver an excessive amount of heat to the brain. Refer to
the sections that follow for guidelines on the interaction of
electromagnetic interference and an implanted Activa System.
Medical Environment
Most routine diagnostic procedures, such as fluoroscopy and x-rays,
are not expected to affect system operation. However, because of
higher energy levels, sources such as transmitting antennas found on
various diagnostic and therapeutic equipment may interfere with the
Activa System.
Effects on Other Medical Devices – The Activa System may affect
the operation of other implanted devices, such as cardiac
pacemakers and implantable defibrillators. Possible effects include
sensing problems and inappropriate device responses. If the patient
requires concurrent implantable pacemaker and/or defibrillator
therapy, careful programming of each system may be necessary to
optimize the patient’s benefit from each device.
Electrocautery – Electrocautery can damage the lead, the
extension, or both. It can also cause temporary suppression of
neurostimulator output and/or reprogramming of the neurostimulator.
If use of electrocautery is necessary, the current path (ground plate)
should be kept as far away from the neurostimulator, extension, and
lead as possible, and use of bipolar electrocautery is recommended.
External Defibrillators – If a patient requires external defibrillation,
the first consideration should be patient survival. Safety for use of
external defibrillatory discharges on patients with neurostimulation
systems has not been established. External defibrillation may
damage a neurostimulator.
If external defibrillation is necessary, follow these precautions to
minimize current flowing through the neurostimulator and lead
system:
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Precautions
■
Position defibrillation paddles as far from the neurostimulator
as possible.
■
Position defibrillation paddles perpendicular to the implanted
neurostimulator-lead system.
■
Use the lowest clinically appropriate energy output (watt
seconds).
■
Confirm neurostimulation system function following any
external defibrillation.
High Radiation Sources – High radiation sources, such as cobalt
60 or gamma radiation, should not be directed at the neurostimulator.
If a patient requires radiation therapy in the vicinity of the
neurostimulator, place lead shielding over the device to prevent
radiation damage.
Lithotripsy – Use of high output ultrasonic devices, such as an
electrohydraulic lithotriptor, is not recommended for patients with an
implanted neurostimulation system. While there is no danger to the
patient, exposure to high output ultrasonic frequencies may result in
damage to the neurostimulator circuitry. If lithotripsy must be used,
do not focus the beam near the neurostimulator.
Psychotherapeutic Procedures – The safety of psychotherapeutic
procedures using equipment that generates electromagnetic
interference (e.g., electroshock therapy, transcranial magnetic
stimulation) has not been established.
Home or Occupational Environment
Home Appliances – Home appliances that are in good working
order and properly grounded do not usually produce enough
electromagnetic interference (EMI) to interfere with neurostimulator
operation. However, items with magnets (e.g., stereo speakers,
refrigerators, freezers, power tools) may cause the neurostimulator to
switch On or Off.
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Precautions
Occupational Environments – Commercial electrical equipment
(arc welders, induction furnaces, resistance welders),
communication equipment (microwave transmitters, linear power
amplifiers, high-power amateur transmitters), and high voltage power
lines may generate enough electromagnetic interference (EMI) to
interfere with neurostimulator operation if approached too closely.
Patient Activities/Environmental Precautions – Patients should
exercise reasonable caution in avoidance of devices which generate
a strong electric or magnetic field. Close proximity to high levels of
electromagnetic interference (EMI) may cause a neurostimulator to
switch On or Off. The system also may unexpectedly cease to
function due to battery depletion or other causes. For these reasons,
the patient should be advised about any activities that would be
potentially unsafe if their symptoms unexpectedly return. For
additional information about devices which generate electromagnetic
interference, call Medtronic at 1-800-707-0933.
Patient Magnet – The magnet provided to the patient for device
activation and deactivation may damage televisions, computer disks,
computer monitors, credit cards, and other items affected by strong
magnetic fields.
Radio Frequency Sources – Analog and digital cellular phones,
AM/FM radios, cordless phones, and conventional wired telephones
may contain permanent magnets. To prevent undesired turning On or
Off of the stimulation, these devices should be kept at least 4 inches
away from the implanted neurostimulator.
Therapeutic Magnets – Therapeutic magnets (for example, those
found in bracelets, back braces, shoe inserts and mattress pads) can
cause inadvertent on or off activations of the neurostimulator.
Therefore, patients should be advised not to use them.
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Clinical Studies and Adverse Events
Clinical Studies and Adverse Events
The clinical use of the Kinetra Model 7428 Neurostimulator is
supported by the Medtronic Parkinson’s disease clinical studies
using the Itrel II Model 7424 Neurostimulator. For results of the
Parkinson’s disease clinical trials and a complete list of adverse
events reported during the Parkinson’s disease clinical trials, refer to
the Activa Clinical Summary packaged with this product.
Because safety and effectiveness of the Activa Parkinson’s Control
therapy was established using bilateral Itrel II neurostimulators,
clinical results and adverse event rates associated with a single dualchannel Kinetra neurostimulator may not be identical.
Individualization of Treatment
For information about individualization of treatment, refer to the
Activa Clinical Summary packaged with this product.
Resterilization
The implantable components of the Activa System were sterilized
with ethylene oxide prior to shipment. The package should be
inspected for damage prior to use. If you are unsure of the
components’ sterility for any reason, they can be resterilized at the
hospital site.
Note: If contamination is suspected because of a defective sterile
package seal, the neurostimulator and accessories can be returned
to Medtronic for replacement or they can be resterilized at the
hospital. Replacements are otherwise subject to the terms of the
Medtronic Limited Warranty (US Customers). Medtronic does not
accept returned neurostimulators or accessories for resterilization
and return them to customers.
Because of variations in hospital sterilizers, precise instructions for
sterilization or aeration cannot be given here. If further information is
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Resterilization
necessary regarding the procedures to be used, contact the
manufacturer of the sterilizer unit. Use biological indicators or other
acceptable methods to validate the effectiveness of the hospital’s
sterilizer unit.
Medtronic cannot accept the responsibility for the hospital’s
resterilization of any components. If, however, the hospital decides to
resterilize, usual and customary sterilization methods should be
used.
# Cautions:
■
Do not resterilize and use the neurostimulator or
accessories after exposure to body tissues or fluids.
■
Do not use radiation to resterilize any component. DO
NOT AUTOCLAVE the neurostimulator. DO NOT CLEAN
the neurostimulator in ULTRASONIC CLEANERS.
Subject to the foregoing, the following may be considered:
Ethylene oxide is an acceptable method for resterilization when the
neurostimulator and accessories are repackaged in an ethylene
oxide-permeable package. The temperature during the process
should not exceed 131° F (55° C). The maximum possible aeration
must be allowed before implanting the neurostimulator and using the
accessories.
Resterilization of a neurostimulator does not change the Use By date
established at the time of manufacture, because the date is based on
battery life.
Steam autoclaving may be used for the hex wrenches only.
To autoclave the hex wrenches, a standard cycle of 30 minutes at
250° F (121° C) and 15 psig is recommended. For “flash” autoclave,
a standard cycle of 5 minutes at 270° F (132° C) and 27 psig is
recommended.
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Directions for Use
Directions for Use
Neurostimulator Implantation or Replacement
This section outlines the basic steps of the suggested procedure for
implanting or replacing the neurostimulator. Refer to the appropriate
extension implant manual for specific information related to the
extension implant procedure. Once the verification of the efficacy of
deep brain stimulation for your patient has been determined during
the test stimulation procedure, the extension and neurostimulator
may be implanted.
To implant the neurostimulator:
1. Remove the percutaneous extension(s), if used, in accordance
with the procedure outlined in the appropriate extension
manual.
2. Create a subcutaneous pocket for the neurostimulator using
blunt dissection in the subclavicular region.
Notes:
■
If MRI is planned, avoid, if possible, implanting the
neurostimulator in the abdomen. This requires the use of a
longer length lead/extension system that can increase
heating from MRI induced RF currents, especially at the
lead electrodes. See “Appendix B: MRI and Activa
Therapy” on page 74 for comprehensive safety information
and instructions.
■
The neurostimulator should be located no more than
1.5 inches (4.0 cm) beneath the surface of the skin in
subcutaneous tissue to allow proper programming. The
device must be placed parallel to the skin surface. The
etched identification side of the neurostimulator must face
outward, away from muscle. When placing two
neurostimulators, ensure a minimum of 8 inches (20 cm)
separates the two to prevent cross-programming.
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Directions for Use
■
In placing the neurostimulator, take into account the
possibility of future cardiac needs (e.g., pacemakers,
defibrillators, etc.). Implanting the neurostimulator on the
right side allows for possible future placement of cardiac
devices on the left side.
Place the neurostimulator away from bony
# Caution:
structures with the etched identification side facing outward,
away from muscle tissue to minimize pain at the
neurostimulator site, and to minimize the possibility of skeletal
muscle stimulation, which may be perceived by patients as
twitching or burning.
3. Place the neurostimulator in the pocket to assure a proper fit
and then remove it.
Tunneling to the Neurostimulator Site
For instructions on tunneling to the neurostimulator site refer to the
appropriate extension manual.
Making the Lead-Extension Connection
For instructions on making the lead-extension connection refer to the
appropriate extension manual.
Making the Extension-Neurostimulator Connection
To make the connection between the extension and the
neurostimulator:
1. Check the neurostimulator connector block and determine if
any setscrews obstruct the socket. If necessary, partially back
out the setscrews.
a. To back out a setscrew, insert the hex wrench through the
pre-pierced hole in the rubber grommet and turn the
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setscrew counterclockwise only until the socket is
unobstructed (Figure 2).
Note: With the Kinetra Model 7428 Neurostimulator, four
setscrews are located on top of the connector module, two for
each extension. Two setscrews are oriented at a 90° angle and
two are oriented at a 45° angle.
Limit counterclockwise rotations of the setscrews.
# Caution:
Rotate enough to provide an unobstructed pathway for
extension connector pins. Too many rotations may disengage
the setscrew from the neurostimulator connector block.
45° Angle
90° Angle
Figure 2. Insert hex wrench in rubber grommet and turn setscrew
counterclockwise to back out setscrew.
b. Wipe off any body fluids from the extension connector pins
and connector block.
c. Check that the encapsulated diagram on the extension
matches the diagram on the neurostimulator.
d. Insert the Extension 1 connector pins fully into Socket I.
Socket I corresponds to electrodes 0-3 on Lead 1.
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e. Insert the Extension 2 connector pins fully into Socket II
(Figure 3). Socket II corresponds to electrodes 4-7 on
Lead 2.
Note: If inserting the extension pins is still difficult, use sterile
water as a lubricant.
Socket I
(Electrodes 0-3)
Socket II
(Electrodes 4-7)
Extension 1
Extension 2
Figure 3. Insert extension connector pins into neurostimulator sockets.
2. Once the extension connector pins are fully inserted in the
neurostimulator sockets, do the following for each of the four
setscrews:
a. Insert the hex wrench through the rubber grommet to
engage the setscrew.
b. Tighten the setscrew by turning the hex wrench clockwise
until resistance is felt (Figure 4).
c. Continue tightening for a maximum of 1/4 turn. The
setscrews must touch the extension connector pins for
proper electrical connection.
Note: When tightening the setscrews, the hex wrench must be
oriented at the same angle as the setscrews (Figure 4).
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# Cautions:
To prevent undertightening the neurostimulator
■
setscrews, do not use the torque wrench from the
extension kit. Undertightening may result in insufficient
electrical contact within the connector block, which may
cause intermittent stimulation.
■
Do not overtighten the setscrews or permanent damage
to the setscrews and/or sockets could result.
■
Be sure the hex wrench is fully inserted to prevent
damage to the setscrew.
■
Verify that each leaf of the sealing rubber grommet has
closed after the wrench is withdrawn. If the grommet
seal is not fully closed, the patient may experience
shocking, burning, or irritation at the neurostimulator
implant site. In addition, fluid leakage into the setscrew
connector block may result in changes to stimulation.
45° Angle
90° Angle
Figure 4. Insert hex wrench and tighten all four setscrews.
Note: The sealing rings within the neurostimulator connector
block are designed to form a seal with the extension connector
pins. No sealant or sutures are required.
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3. Place the neurostimulator into the subcutaneous pocket
(Figure 5). Position the neurostimulator so that no sharp bends
occur along the extension or lead (Figure 6).
Place the neurostimulator away from bony
# Caution:
structures and with the etched identification side facing
outward, away from muscle tissue to minimize pain at the
neurostimulator site, and to minimize possibility of skeletal
muscle stimulation, which may be perceived by the patient as
twitching or burning.
Figure 5. Place neurostimulator into subcutaneous pocket.
Do not loop or coil the extension on top of the
# Caution:
neurostimulator’s etched identification side. Wrap any excess
extension wire around the perimeter of the neurostimulator
(Figure 6). This avoids any increase in subcutaneous pocket
depth, minimizes potential damage during replacement
surgery, and minimizes potential kinking of the extension wire.
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Figure 6. Wrap excess wire around the perimeter of the neurostimulator.
4. Secure the neurostimulator in the subcutaneous pocket, using
the suture holes in the connector block to secure it to the
muscle fascia. (Figure 7).
Suture Holes
Figure 7. Suture hole locations on neurostimulator connector block.
5. Check the stimulation parameters.
6. Confirm that the desired program is stimulating the desired
area (e.g., that Program 1 (Lead 1) stimulates the left side and
Program 2 (Lead 2) stimulates the right side).
7. Close and dress the incision.
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8. Complete the patient registration form and mail it to Medtronic.
If the neurostimulator case is ruptured or pierced
w Warning:
after implant due to outside forces, severe burns could result
from exposure to battery chemicals.
Note: If only one lead is implanted at this time, perform the
following steps using the accessories from the Model 3550-09
Accessory Kit:
■
1 Lead, 1 Extension—Insert the neurostimulator
connector plug into the unused socket of the
neurostimulator connector block and tighten the setscrews
(Figure 8).
Figure 8. Insert connector plug into unused neurostimulator socket.
■
1 Lead, 2 Extensions—Slide the closed boot over the
extension’s setscrew connector and secure with sutures
(Figure 9).
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Figure 9. Slide closed boot over extension setscrew connector and suture.
To replace the Kinetra Neurostimulator:
1. Open the neurostimulator implant site per normal surgical
procedure, and carefully remove the neurostimulator from the
subcutaneous pocket.
Use care to avoid damaging the extension wire
# Caution:
which may be wrapped around the perimeter of the
neurostimulator.
2. Clean the neurostimulator and extension connector with sterile
water; wipe both dry with surgical sponges.
3. Insert the hex wrench included in the package through the prepierced hole in the rubber sealing grommet, and loosen the
setscrews by turning counterclockwise (Figure 2).
4. Gently retract the extension pins from the neurostimulator
connector. If the extension pins show any signs of pitting
corrosion, the extension should be replaced. Clean and dry
both the pins and extension connector body—they must be
free of fluids or tissue.
5. Check the neurostimulator connector and determine if any
setscrews obstruct the socket space. If necessary, back out the
setscrews.
6. Insert the Extension 1 connector pins fully into Socket I. Socket
I corresponds to electrodes 0-3 on Lead 1.
7. Insert the Extension 2 connector pins fully into Socket II (refer
to Figure 3). Socket II corresponds to electrodes 4-7 on
Lead 2.
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8. Tighten each setscrew clockwise until it touches the connector
pin—continue tightening for a maximum of 1/4 turn only
(Figure 4). When tightening the setscrews, the hex wrench
must be oriented at the same angle as the setscrews (refer to
Figure 4). After you remove the wrench, check that the sealing
rubber grommet has closed.
# Cautions:
To prevent undertightening the neurostimulator
■
setscrews, do not use the torque wrench from the
extension kit. Undertightening may result in insufficient
electrical contact within the connector block, which may
cause intermittent stimulation.
■
Do not overtighten the setscrews or permanent damage
to the setscrews and/or sockets could result.
■
Be sure the hex wrench is fully inserted to prevent
damage to the setscrew.
■
Verify that each leaf of the sealing rubber grommet has
closed after the wrench is withdrawn. If the grommet
seal is not fully closed, the patient may experience
shocking, burning, or irritation at the neurostimulator
implant site. In addition, fluid leakage into the setscrew
connector block may result in changes to stimulation.
9. Place the new neurostimulator into the subcutaneous pocket,
with the etched identification side facing outward, and secure.
Note: The neurostimulator should be located no more than
1.5 inches (4.0 cm) beneath the surface of the skin in
subcutaneous tissue to allow proper programming. The device
must be placed parallel to the skin surface. The etched
identification side of the neurostimulator must face outward,
away from muscle. If another neurostimulator is already
implanted or planned for the future, ensure at least 8 inches
(20 cm) between the two.
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# Cautions:
■
Place the neurostimulator away from bony structures and
with the etched identification side facing outward, away
from muscle tissue to minimize pain at the neurostimulator
site, and to minimize possibility of skeletal muscle
stimulation, which may be perceived by the patient as
twitching or burning.
■
Do not loop or coil the extension on top of the
neurostimulator’s etched identification side. Wrap any
excess extension wire around the perimeter of the
neurostimulator (Figure 6). This avoids any increase in
subcutaneous pocket depth, minimizes potential damage
during replacement surgery, and minimizes potential
kinking of the extension wire.
10. Use the suture holes in the connector block to secure the
neurostimulator in the subcutaneous pocket. Use normally
available surgical needles and sutures.
11. Check the stimulation parameters.
12. Confirm that the desired program is stimulating the desired
area (e.g., that Program 1 (Lead 1) stimulates the left side and
Program 2 (Lead 2) stimulates the right side).
13. Close the neurostimulator pocket incision.
14. Fill out and mail the implant registration form to Medtronic.
If the neurostimulator case is ruptured or pierced
w Warning:
after implant due to outside forces, severe burns could result
from exposure to battery chemicals.
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Explant Disposition
Explanted products must be returned to Medtronic for proper
disposal. Please include an explanation of explant on the Returned
Product Information Report that is packaged with the Self-addressed
Mailer Kits provided by Medtronic.
Return explanted products to:
Medtronic Inc.
Neurological Division
Returned Product Analysis
MS N600
P.O. Box 1250
Minneapolis, MN 55440-9087
The self-addressed mailer kits are available from your Medtronic
Sales Representative.
Environmental Problems
Kinetra neurostimulators are designed to assure immunity from most
common sources of electromagnetic interference (EMI). Because
many different types of EMI sources exist, it is impossible to specify
all interference sources here. However, the most common sources of
EMI are discussed below.
Hospital or Medical Environment
Kinetra neurostimulators have been tested for electromagnetic
compatibility (EMC) in electrical and magnetic fields that simulate
common sources of EMI found in a hospital environment. Severe
electromagnetic fields, such as those that exist near electrocautery
equipment, can reprogram a neurostimulator, temporarily suppress
the output of a neurostimulator, and cause damage to the implanted
system components.
Telemetry usually continues to function but may indicate that the
neurostimulator output is On when, in fact, no stimulation is being
delivered because the amplitude is set to 0.0 V. Kinetra
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neurostimulators have a protective circuit to prevent damage to the
circuitry, but a large burst of electromagnetic energy may temporarily
affect the output and/or the ability to reprogram the device. Severe
EMI (e.g., electrocautery, defibrillatory discharge, MRI) can also
erase the neurostimulator serial number.
Refer to the section Precautions: Medical Environment for
information on the interaction between specific medical equipment
and the Activa System.
Home or Job Environment
Kinetra neurostimulators should not be affected by normal operation
of electrical equipment such as household appliances, electric
machine shop tools, microwave ovens, RF transmitting systems, or
microwave frequency transmitting systems. A strong magnetic field
(electromagnet or permanent magnet) can switch the
neurostimulator output from On to Off or Off to On1, but does not
change the programmed parameters.
In addition, theft detectors and airport/security screening devices can
affect the neurostimulator output and patient stimulation.
Advise your patients to use care when approaching theft detectors or
airport/security screening devices. If they feel unwanted stimulation
as they approach the device, suggest that they request assistance to
bypass the device.
1
Unexpected On/Off switching of the Kinetra Model 7428 Neurostimulator may be
avoided by disabling the magnet control circuit with the clinician programmer software.
If the magnet control circuit is disabled, patients will require a Model 7436 Therapy
Controller to turn their therapy On or Off. Refer to “Control Magnet” on page 44.
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Theft detectors found in retail stores, public
w Warning:
libraries, etc., and airport/security screening devices may
cause the stimulation power source of an implantable
neurostimulation system to switch On or Off. It is also possible
that sensitive patients, or those with low stimulation
thresholds, may experience a momentary increase in their
perceived stimulation. For other indications, higher levels of
stimulation have been described as uncomfortable (“jolting” or
“shocking”) by some patients as they pass through these
devices. Refer to “Patient Counseling Information” on page 36
for more information.
Advise your patients to avoid or to exercise care when approaching
the following:
■
Theft detectors
■
Airport/security screening devices
■
Large stereo speakers with magnets
■
Electric arc welding equipment
■
Electric steel furnaces
■
Electric induction heaters (used in industry to bend plastic)
■
Power lines
■
Electric substations and power generators
If your patient suspects an electrical device or magnet is interfering
with the neurostimulator, advise him/her to move away from it, or turn
the device off. Then, the patient can use the control magnet or
therapy controller to set the neurostimulator back to the desired On
or Off state. When switched On, the neurostimulator will resume
stimulation at the previously programmed level.
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Handling and Storage
The neurostimulator can be damaged if dropped on a hard surface,
that is, dropped from a height of 30 cm (12 in.) or more onto a surface
like a concrete floor. If this happens, the unit should not be implanted.
The neurostimulator should not be stored at temperatures above
131° F (55° C) or below 0° F (-18° C).
Patient Registration
Inside the shipping container for each Kinetra Neurostimulator is an
implant registration form that creates a permanent record of your
patient’s implant. It is important that you complete the form and
promptly return the original to Medtronic, Inc. Three copies are
provided for the patient’s medical records.
Medtronic will transfer vital information to a wallet-sized, plasticcoated identification card and will mail it directly to the patient. A
temporary identification card is packaged with the neurostimulator for
the patient’s use until the permanent card arrives.
In addition to the patient identification card, the information on the
form registers the device warranties and creates a record of the
implant in Medtronic’s implant data system. The information in this
system ensures compliance with the Safe Medical Devices Act
(USA).
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Physician Training Information
Physician Training Information
Prescribing physicians should have expertise in the medical
treatment of patients with movement disorders. Implanting
physicians should have expertise with functional stereotactic
neurosurgical treatment of movement disorders. Such expertise
should include knowledge of the anatomical and neurophysiological
characteristics of the targeted nucleus, surgical and /or implantation
techniques for the Activa System, operational and functional
characteristics of the Activa System, and experience in the continued
management of patients by stimulation parameter adjustment.
Physicians may contact Medtronic before prescribing or implanting
an Activa System for the first time and request a referral to a
physician experienced in the use of Activa Therapy.
All Activa System programming should be by or under the
supervision of a physician or other experienced medical personnel
familiar with the use of the programming software and equipment.
Physicians should be thoroughly familiar with Activa System
supporting material, including:
■
All product labeling, and
■
Education and training materials.
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Patient Counseling Information
Patient Counseling Information
Before surgery, the patient and family should be advised of the known
risks of the surgical procedure and the therapy, as discussed in other
sections of this manual, as well as the potential benefits. After the
Activa System is implanted, the patient should also be advised to
read the patient manual included in the neurostimulator package.
Theft Detectors and Screening Devices
Patients should be advised to use care when approaching security
arches or gates (such as those found in airports, libraries, and some
department stores) because these devices can turn on or turn off
their neurostimulator. If an airport security wand is used, they should
ask the security personnel to avoid placing the wand over the
neurostimulator.
When approaching these devices, patients should do the following:
1. If security personnel are present, show them the
neurostimulator identification card and request a hand search.
2. If patients must pass through the security device, they should
approach the center of the device and walk normally
(Figure 10).
a. If two security gates are present, they should walk through
the middle, keeping as far away as possible from each
gate.
b. If one gate is present, they should walk as far away as
possible from it.
Note: Some theft detectors may not be visible.
3. Proceed through the security arch or gate. Do not touch, lean
on or linger near the security arch or gate.
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Double
Security
Gate
Single Security
Gate (Stay as far
away as possible
from gate)
Figure 10. Approaching security gates.
4. If patients suspect that their neurostimulator was turned off,
they should make sure someone is able to turn on the system
again. (This person could be the patient, if his or her medical
condition allows it. It could also be a family member or clinician
who has been taught how to use the system.)
Component Manipulation by Patient
Advise your patient to avoid manipulating the implanted system
components (e.g., the neurostimulator, the burr hole site). This can
result in component damage.
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Kinetra Patient Eligibility
Kinetra Patient Eligibility
Prior to neurostimulator implant, ensure that the Kinetra
Neurostimulation System is appropriate for your patient.
Rate Control
If independent rate control is desired to provide adequate symptom
control for your patient, be aware that rate parameter values are not
independently programmable with the Kinetra Model 7428
neurostimulator. Consider implanting two Soletra Model 7426
neurostimulators if independent rate values are desired.
Note: In Medtronic’s clinical studies of the Itrel II Model 7424
neurostimulator for advanced Parkinson’s disease, at least 58% of all
subjects had identical rates bilaterally at all follow-up visits.
Screening for Patient Eligibility
Verify that the screening parameters do not exceed the maximum
amplitude shown in Table 1 on page 39. If test stimulation is
unsuccessful or if parameter settings to achieve therapeutic benefit
are within the charge density warning area (refer to Figure 13 on
page 52), the system should not be implanted.
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Table 1. Maximum Amplitude (Volts) Available for Specific Rate/Pulse
Width Combinations.a,b
Pulse Width (Microseconds)
Rate (Hz)
a
b
60
90
120
150
180
210
130
9.5 V
9.5 V
9.5 V
9.0 V
8.0 V
7.5 V
140
9.5 V
9.5 V
9.0 V
8.5 V
8.0 V
7.5 V
150
9.5 V
9.5 V
9.0 V
8.0 V
7.5 V
7.0 V
160
9.5 V
9.5 V
8.5 V
8.0 V
7.0 V
6.5 V
170
9.5 V
9.5 V
8.5 V
7.5 V
6.5 V
6.5 V
185
9.5 V
9.0 V
8.0 V
7.0 V
6.5 V
6.0 V
200
9.5 V
8.5 V
7.5 V
7.0 V
6.0 V
5.5 V
220
9.0 V
8.0 V
7.5 V
6.5 V
5.5 V
5.0 V
250
9.0 V
7.5 V
7.5 V
5.5 V
5.0 V
4.5 V
This table is based on data collected with a 1000 ohm resistive load. If the screening
rate is between table settings, use the next higher rate.
The shaded area has upper limits that exceed the charge density warning threshold.
See Figure 13 on page 52.
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Detailed Device Description
Detailed Device Description
General Description
The Kinetra Neurostimulator has a wide range of noninvasively
programmable parameters and stimulation modes. The
neurostimulator provides current parameter information, via
telemetry, when used with the clinician programmer. The following
sections outline the major neurostimulator features.
Programs
The stimulation pulses delivered to each lead are determined by a
parameter called a program. A program is a specific combination of
amplitude, rate, and pulse width parameters acting on a specific
electrode set. The Kinetra Model 7428 Neurostimulator has two
available programs (P1 and P2). Program 1 corresponds to Lead 1
(electrodes 0-3 and the case) and Program 2 corresponds to Lead 2
(electrodes 4-7 and the case). Rate is not independently
programmable; one programmed setting determines the rate for both
programs.
Dual-Program Stimulation
Dual-program pulses are delivered alternately rather than
simultaneously. Program 1 delivers an output pulse at its
programmed amplitude and pulse width parameters, followed by the
Program 2 output pulse at its programmed amplitude and pulse width
parameters. This sequence is repeated, with single output pulses
alternately delivered. Figure 11 illustrates dual-program operation.
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Different amplitude and
pulse width on both
programs1
Same amplitude and pulse
width on both programs1
1
Lead 1 (P1)
Lead 2 (P2)
Lead 1 (P1)
Lead 2 (P2)
Rate is always the same for both programs
Figure 11. Examples of dual-program stimulation.
Programmable Functions
The Kinetra Neurostimulator is programmed with either the Model
7432 Clinician Programmer and the MemoryMod Model 7459
Software Cartridge or the Model 8840 Clinician Programmer and the
Model 8870 Application Card.
The clinician programmer is used to program the stimulation
parameters for both programs by telemetry. It controls various
parameters and stimulation modes (Table 2). The clinician
programmer displays instruction “prompts” and shows parameter
data. A “hard-copy” printout can also be produced during a
programming sequence. Some features include Day Cycling,
SoftStart/Stop, and Control Magnet Enable/Disable. Patient use
information is also available. Neurostimulator internal counters
automatically monitor items such as total stimulation time and total
number of activations.
The Access Model 7436 Therapy Controller allows the patient to turn
the neurostimulator on and off and check the neurostimulator battery
status (device shipped with these features active). In addition, the
Kinetra Neurostimulator can be programmed with upper and lower
limits for amplitude, pulse width, and rate. The Kinetra
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Neurostimulator is shipped with these optional limits set to ±0. When
these optional limits are enabled by the physician, patients can adjust
their stimulation within the prescribed limits using the therapy
controller. These optional limits may not be appropriate for all
patients. Physician discretion will need to be exercised to determine
whether an individual patient or caregiver is capable of managing
parameter control.
For a complete description of programmable functions, refer to the
manuals supplied with the software and therapy controller.
Programmers made by other manufacturers are not compatible with
the Kinetra Model 7428 Neurostimulator.
Table 2. Kinetra Model 7428 Controlling Devices and Functions.
Controlling Device
Function
7432 Programmer
with 7459 Software
8840 Programmer
with 8870 Software
• Switches Neurostimulator Output On/Off and
provides neurostimulator battery status
• Programs Stimulation Parameters and limits for
Programs 1 and 2
• Programs Stimulation Modes
• Collects Measurements and Diagnostic Data
• Programs Special Features
7436 Therapy
Controller
• Switches Neurostimulator Output On/Off
• Gives Neurostimulator On/Off Status
• Adjusts Stimulation Parameters within
Physician Prescribed Limits for both Programs
• Provides Neurostimulator Battery Status
7452 Control
Magnet
• Switches Output On/Off if the magnet function
has been enabled with the clinician
programmer
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For a description of programmer operations and programming
functions, refer to the appropriate hardware technical manual or
software programming guide.
Telemetry Data
The Kinetra neurostimulator is capable of providing telemetry data
transmissions when properly reviewed by the clinician programmer.
Upon interrogation, Kinetra neurostimulators will transmit the
following via a radiofrequency (RF) link to the clinician programmer
for display or printing:
■
Model and serial number identification
■
Programmed parameters and values
■
Neurostimulator battery status
■
Number of patient activations (since last reset)
■
Total stimulation time (since last reset)
■
Elapsed time (since last reset)
■
Verification of program changes
After a program entry, the programmer compares neurostimulator
parameters, via telemetry, with the entries made during
programming. The neurostimulator parameter or mode is changed to
match the entry and the new value or mode is registered on the
display.
Do not send a patient home with any invalid values
# Caution:
for programmable parameters displayed on the programmer
screen. They must be reprogrammed to valid parameter
values. Note that severe EMI (e.g., electrocautery,
defibrillatory discharges, MRI) can erase the neurostimulator
serial number.
Only the clinician programmer can receive and display telemetry data
from the neurostimulator.
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Control Magnet
The control magnet enables your patient to switch the
neurostimulator output On or Off. The patient briefly applies the
Medtronic Model 7452 Control Magnet over the implanted
neurostimulator and then removes it to turn the neurostimulator On
or Off. Application of the magnet for 2 seconds followed by removal
causes the output circuit to turn On or Off.
The magnet On/Off control circuit is enabled when the flat edge of the
magnet is applied over the neurostimulator implant site for 2 seconds
(Figure 12). The actual switching occurs when the magnet is
withdrawn. The magnet On/Off control circuit does not affect
programmed parameters; when the output is switched On using the
magnet, the output resumes its previously programmed waveform
and stimulation mode.
Magnet
Figure 12. Magnet properly positioned over neurostimulator.
The magnet control circuit can be disabled with the clinician
programmer software. Patients who are exposed to magnets or
strong electromagnetic fields may experience unexpected On/Off
switching of their neurostimulators. If On/Off switching occurs, you
can disable the magnet control circuitry with a command to the
neurostimulator from the clinician programmer. The magnet control
circuit can later be enabled with another command from the clinician
programmer, if desired. Detailed instructions on this disable feature
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are contained in the programming guide provided with the clinician
programmer.
If the On or Off control by the magnet-actuated reed
# Caution:
switch is disabled, the patient must have a therapy controller
to turn the neurostimulator on or off.
Neurostimulator Counters
Patient Activations – Each time the neurostimulator is turned On,
the activation is counted on the Patient Activation Counter. This
counter will count up to 32,767 patient activations, and it can be read
by telemetry and reset by a special programming command.
Total Stimulation Time – The total stimulation time is the amount of
time the neurostimulator is On (with amplitude > 0) since the counter
was last reset. It is a cumulative total with a counter capacity of 8,738
hours, or approximately 1 year. If cycling is programmed, Off cycle
time is included.
Elapsed Time – The elapsed time is the amount of total time since
the counters were last reset. The capacity of this counter is 8,192
hours, or approximately one year.
Counter Reset – All counters can be reset with the clinician
programmer.
Postoperative Patient Management
The treating clinician(s) should be experienced in all aspects of the
medical management of patients with Parkinson’s disease. Clinicians
using Activa Therapy for the first time are encouraged to contact a
Medtronic representative for information on the postoperative
management of Activa patients.
When programming stimulation parameters, give consideration to the
following programming recommendations regarding initial stimulation
parameters.
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Programming Initial Stimulation Parameters for Activa
Parkinson’s Control Therapy – The following procedure provides
instructions on programming post-operative stimulation parameters
for Activa Parkinson’s Control Therapy, and is one approach for the
physician’s consideration.
Notes:
■
High amplitude/pulse width combinations can result in
excessive charge density. Refer to “Programming
Stimulation Parameters” on page 49 for more information.
■
With the Kinetra Model 7428 Neurostimulator operating in
a dual-program configuration, select stimulation
parameters for Program 1 (Lead 1) and Program 2 (Lead
2).
■
If independent rate control is desired to provide adequate
symptom control for your patient, be aware that rate
parameter values are not independently programmable
with the Kinetra Model 7428 neurostimulator.
1. Allow sufficient time for the patient to recover from surgery.
Schedule the initial programming visit so that the patient is in
an “off” period, when the Parkinson’s disease symptoms are
predominant.
2. Set the neurostimulator to the initial settings provided in
Table 3.
3. To evaluate the potential effectiveness of all electrodes, select
a predominant Parkinson’s disease symptom, such as rigidity
or tremor, that responds to changes in stimulation.
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Table 3. Programming Settings for Activa Parkinson’s Control Therapy
Parameter
Typical Initial
Setting
Range/
Options
Typical Final
Setting
Amplitude
0.0 V
Normal:
0-10.5 V
Fine:
0-6.35 V
2.5-3.5 V
Pulse Width
60-120 µsec
60-450 µsec
60-120 µsec
Ratea
130-160 pps
3-250 pps
130-185 pps
Unipolar
Unipolar
or
Bipolar
Variesb
Continuous
Cycling or
Continuous
Continuous
Electrode
Polarity (Refer to
“Electrode
Programming
Configurations”
on page 53)
Mode
a
b
The same value for rate is programmed for both Program 1 and Program 2.
In the Medtronic-sponsored clinical investigation, most STN patients used unipolar
stimulation, whereas similar proportions of GPi patients used unipolar and bipolar
stimulation.
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4. To expedite electrode selection, program the neurostimulation
system to a unipolar electrode configuration where the
neurostimulator case is the positive electrode, electrode 0 is
the negative electrode for Program 1, and electrode 4 is the
negative electrode for Program 2.
Note: It may be desirable to ultimately program the
neurostimulation system to a bipolar electrode configuration,
where both the positive and negative electrical poles are the
lead electrodes. This can reduce the potential for
electromagnetic interference-related side effects, and may
optimize battery life.
5. Gradually increase amplitude by 0.1 - 0.5 V incrementally until
a predominant Parkinson’s disease symptom (rigidity, tremor)
is suppressed. Wait a few minutes to assess the effect of
stimulation.
6. If there is uncomfortable stimulation or inadequate symptom
suppression, reduce the amplitude to 0 V and select another
electrode as the negative electrode. Repeat step 5. Select the
electrode that provides the best control of symptoms with the
fewest side effects.
7. After the most desirable negative electrode is selected,
gradually increase the amplitude until side effects occur. The
therapeutic window between symptom suppression and
occurrence of side effects should be sufficiently wide to allow
for future amplitude adjustments.
8. Evaluate the patient in an “on” period, when Parkinson’s
disease symptoms are controlled after a usual dose of
antiparkinsonian medication. Assess the effect of stimulation
on suppressing or worsening of dyskinesias.
9. After Amplitude settings are determined, adjust Pulse Width
and Rate to improve therapeutic benefit and minimize side
effects.
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Notes:
■
Symptom suppression is desirable at the lowest possible
amplitude, rate, and pulse width in order to improve battery
longevity and minimize charge density.
■
The same value for rate is programmed for both Program 1
and Program 2.
10. Document final parameter settings for future reference.
Programming Stimulation Parameters
When programming stimulation parameters, give consideration to the
following recommendations regarding high output interlocks and
charge density.
High Output Interlocks – Certain combinations of high amplitude,
pulse width, and rate stimulation settings are not allowed by the
clinician programmer. If you attempt to program a parameter value
(or limit) that will cause the settings to exceed the high output
interlock limit, the desired parameter value can only be achieved by
reducing one of the other parameter values. Refer to Table 4 for
information on limited amplitude at high programmed rate and pulse
width combinations.
Note: If the upper limit for amplitude, pulse width, or rate is
programmed to a higher value than the programmed value, the
programmer will use this value when determining a high output
interlock.
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Table 4. Maximum Programmable Amplitude at High Rate/Pulse Width
Combinations.
Programmed
Limited Amplitude at High Rates (Hz)
PW (µsec)
130
150
175
200
220
250
90
10.5 V
10.5 V
10.4 V
9.9 V
9.5 V
9.1 V
120
10.4 V
10.0 V
9.5 V
9.0 V
8.6 V
8.1 V
180
9.2 V
8.7 V
8.1 V
7.6 V
7.0 V
6.4 V
240
8.3 V
7.7 V
7.1 V
6.6 V
6.0 V
5.5 V
300
7.3 V
6.8 V
6.2 V
5.7 V
5.4 V
5.0 V
360
6.8 V
6.2 V
5.6 V
5.0 V
4.7 V
4.3 V
420
6.4 V
5.9 V
5.3 V
4.8 V
4.5 V
4.1 V
450
6.0 V
5.5 V
4.8 V
4.2 V
3.8 V
3.4 V
Charge Densities – A survey of literature regarding electrical
stimulation of neural tissue suggests that damage may occur above
30 microcoulombs/cm2/phase. The Activa System is capable of
producing charge densities in excess of 30 microcoulombs/cm2/
phase (Figure 13).
The device’s maximum amplitude is 10.5 V, and maximum pulse
width is 450 microseconds. The curved lines in Figure 13 represent
a charge density of 30 microcoulombs/cm2/phase at various
impedance measurements, calculated for the electrode surface area
of the DBS Model 3387/3389 Lead. Mean resistance found in the
clinical studies were as follows.
■
Parkinson’s disease clinical studies (all targets): 1294 ohms
(range: 415-1999 ohms).
■
Parkinson’s disease clinical studies (GPi): 1161 ohms
(range: 415-1967 ohms).
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■
Parkinson’s disease clinical studies (STN): 1177 ohms
(range: 628-1926 ohms).
Charge density is determined by plotting a point corresponding to the
pulse width setting (x-axis), and the amplitude setting (y-axis). If this
point is below the appropriate resistance curve, then the charge
density is below 30 microcoulombs/cm2/phase. Points above the
curve indicate a charge density above 30 microcoulombs/cm2/
phase.
The shaded area of Figure 13 indicates a charge density above 30
microcoulombs/cm2/phase at the conservative impedance estimate
of 500 ohms. If stimulation parameters are selected that fall into the
shaded area of the graph, the following programmer warning
appears: WARNING: CHARGE DENSITY MAY BE HIGH ENOUGH
TO CAUSE TISSUE DAMAGE. Programming may continue at the
desired values (refer to the appropriate software application manual
for further information).
Figure 13 includes two examples of charge density calculated for the
Activa System. In Example A, the Kinetra Model 7428
Neurostimulator is set to typical parameter settings for symptom
suppression: amplitude = 3.0 V and pulse width = 90 µsec. The
charge density for Example A is below the shaded warning zone,
thus indicating a charge density below 30 microcoulombs/cm2/phase
at the most conservative impedance of 500 ohms.
In Example B, neurostimulator stimulation parameters are set to:
amplitude = 6.1 V and pulse width = 210 µsec. The charge density at
these settings is in the shaded area indicating it may be high enough
to cause tissue damage at an impedance of 500 ohms. However, as
shown in Figure 13, if the impedance in this case is at the clinical
mean from the Parkinson’s disease clinical study, the charge density
would be below 30 microcoulombs/cm2/phase.
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Amplitude (Volts)
DBS Amplitude and Pulse Width Limits
Computed for resistances ranging from 500 to 2,000 ohms
DBS Lead Surface Area = 0.06 cm2
Charge Density Threshold = 30 Microcoulombs/cm2/phase
Pulse Width (Microseconds)
Figure 13. Charge density with Parkinson’s disease clinical mean resistance.
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Electrode Programming Configurations
The Kinetra Neurostimulation System offers two types of
configurations: unipolar (neurostimulator case positive, lead
electrode(s) negative) and bipolar (neurostimulator case off, one or
more lead electrodes positive and one or more lead electrodes
negative). In addition, by selecting and activating different
combinations of electrodes available for the neurostimulation system,
the stimulation can be tailored to individual patient therapy
requirements.
Some of the advantages and disadvantages of the configurations are
discussed below. When selecting the configuration, check the impact
on battery life. For more information on battery longevity, refer to
“Appendix A: Battery Longevity Reference Information” on page 64.
For more information on the leads or the extensions, refer to the
technical manual packaged with the product.
Use only leads that are compatible with the output
w Warning:
capabilities of the neurostimulator. Refer to the system
components sheet.
Bipolar Configurations – In a bipolar configuration, at least one
lead electrode is positive and at least one lead electrode is negative,
with the neurostimulator case Off. Using a bipolar configuration with
one negative lead electrode and one positive electrode may
maximize battery life.
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Unipolar Configurations – In a unipolar configuration, one or more
lead electrodes are negative and the neurostimulator case is positive.
Check the effect on battery life. Refer to “Appendix A: Battery
Longevity Reference Information” on page 64.
Note: Activating more than the minimum number of electrodes in
either unipolar or bipolar configurations spreads the stimulation
over a greater area, but may reduce the battery life. Activate
additional electrodes only after other electrode combinations have
been tried. However, check the effect on battery life. For more
information on battery longevity, refer to “Appendix A: Battery
Longevity Reference Information” on page 64.
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Front
Back
Figure 14. Electrode Configuration.
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Test Stimulation
An intraoperative test stimulation phase during the lead implant
procedure verifies a correct lead placement that results in symptom
suppression with minimal side effects. Perform test stimulation
intraoperatively. If there is no symptom suppression, do not implant
the Activa System. Instructions for the test stimulation are included in
the DBS Lead Implant Manual and the Model 3625 Test Stimulator
Operator Manual.
Specifications and Features
The Kinetra Neurostimulator is powered by a hermetically sealed,
silver vanadium oxide cell and uses integrated circuits. To protect the
neurostimulator components from intrusion of body fluids, the
electronics and power source are hermetically sealed within an ovalshaped titanium shield.
Refer to Table 5 for a list of the parameter operating ranges, to
Table 6 for parameter settings at shipping, and to Table 7 for the
physical characteristics of the neurostimulator. The Kinetra Model
7428 Neurostimulator case has an external insulating coating to help
minimize possible skeletal muscle stimulation at the neurostimulator
implant site. An uninsulated area on one side of the neurostimulator
(etched identification side) can serve as the positive electrode when
using a unipolar configuration. The uninsulated side should be
positioned outward, away from muscle tissue, toward the exterior of
the body.
Kinetra neurostimulators have a self-sealing connector assembly
with a corrosion-resistant titanium-alloy body and titanium setscrews.
This connector assembly can accommodate two extensions to form
a dual-program system. Securing the extension requires the use of
the hex wrench that is packaged with the neurostimulator.
Other features of Kinetra neurostimulators include: two suture holes
to enable you to secure the neurostimulator within the subcutaneous
pocket; Power On Reset (POR); and a radiopaque identification
code.
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Table 5. Kinetra Model 7428 Neurostimulator
Programmable Parameter Values.
Programmable
Parameters
Valuesa
Pulse Amplitude b
and Limits for
Programs 1 and 2
Normal resolution: 0 to 10.5 V (0.1 V steps)
Fine Resolution: 0 to 6.35 V (0.05 V steps)
Rate and Limitsb,c
66 values from 3 to 250
Pulse Width and
Limits for Programs
1 and 2b
60, 90, 120, 150, 180, 210, 240, 270, 300, 330,
360, 390, 420, 450 µsec
Cycle On Time
0.1 second to 24 hours
Cycle Off Time
0.1 second to 24 hours
Cycle On Time
w/SoftStart
2 seconds to 24 hours
Cycle Off Time
w/SoftStart
2 seconds to 24 hours
SoftStart/Stop
1, 2, 4, or 8 seconds
Electrode Polarity
for Program 1
0, 1, 2, 3, Electrodes: Off, Neg or Pos
Case: Off or Pos
Electrode Polarity
for Program 2
4, 5, 6, 7, Electrodes: Off, Neg or Pos
Case: Off or Pos
Day Cycling ON
Time
30 minutes to 24 hoursd
Day Cycling OFF
Time
30 minutes to 24 hoursd
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Table 5. Kinetra Model 7428 Neurostimulator
Programmable Parameter Values. (continued)
a
b
c
d
Programmable
Parameters
Valuesa
Magnet ON/OFF
Control Circuit
Enabled or Disabled
Note: All values are approximate.
Note: Certain combinations of amplitude, pulse width, and rate are not allowed. Refer
to “High Output Interlocks” on page 49.
The same values for rate and rate limits are programmed for both Program 1 and
Program 2.
The sum of the ON and OFF times must equal 24 hours.
Table 6. Kinetra Model 7428 Neurostimulator
Shipping Settings.
Description
Value
Amplitude for Programs 1 and 2
(Normal Resolution)
Upper Limit
Lower Limit
0 volts
Rate for Programs 1 and 2
Upper Limit
Lower Limit
130 pps
+0 pps tracking
-0 pps tracking
Pulse Width for Programs 1 and 2
Upper Limit
Lower Limit
90 µsec
+0 µsec tracking
-0 µsec tracking
Output On/Off Switch
Offa
Mode
Continuous Dual-Program
+0 volts tracking
-0 volts tracking
SoftStart/Stop
4 seconds
Magnet Control Circuit
Enabled
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Table 6. Kinetra Model 7428 Neurostimulator
Shipping Settings. (continued)
a
Description
Value
Electrode Polarity for Program 1
0 = Negative
1 = Off
2 = Off
3 = Positive
Case = Off
Electrode Polarity for Program 2
4 = Negative
5 = Off
6 = Off
7 = Positive
Case = Off
Note: Exposure to a strong source of electromagnetic interference (EMI) can cause
the output switch to toggle to the On position. However, since the Amplitude setting is
0.0 V, there is no neurostimulator output.
Table 7. Kinetra Model 7428 Neurostimulator Physical Description
Description
a
b
Valuea
Height
2.4 in. (61 mm)
Length
3.0 in. (76 mm)
Thickness
Case
Connector
0.527 in. (13.4 mm)
0.590 in. (15.0 mm)
Weight
2.9 oz (83 g)
Volume
3.1 in3 (51 cm3)
External Shield
Titaniumb
Storage Temperature
-18° C to +55° C
0° F to +131° F
All values are approximate.
Note: The Kinetra Model 7428 Neurostimulator has an insulating coating to prevent
undesirable muscle stimulation. The uninsulated side with the etched identification
should be positioned outward, away from the muscle.
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Kinetra Neurostimulator Battery Longevity
“Appendix A: Battery Longevity Reference Information” on page 64 in
this manual can be used to help you estimate battery longevity for the
Kinetra Neurostimulator at various parameter settings. The fewer the
number of stimulation hours used daily, the longer the total longevity.
The battery information provided in the appendix is theoretical. In
actual use, parameters, usage time, and other factors such as
impedance, may vary. Therefore, the tables and formulas cannot
predict precise longevity for any given patient. However, once battery
life is estimated, it is possible to set realistic expectations of battery
life and achieve optimal battery life from the Kinetra Neurostimulator.
Note: Battery life estimates are for a new implant and therefore
should be made at the time of implant.
Battery Status Indicators
The clinician programmer enables you to monitor your patient’s
neurostimulator battery status. The programmer provides both
voltage and current measurements. For example, as the
neurostimulator battery depletes, the telemetry readout will show
LOW on the programmer’s display. If you use the printer, it will print
LOW. As the battery voltage decreases further, the clinician
programmer shows the battery status as EOL (End of Life) on the
display, or prints EOL. After the neurostimulator battery has been
depleted, telemetry is no longer possible. Refer to the table below for
a summary of battery status messages and their meaning.
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a
Battery Status Indicators
Battery Voltage Level
OK
Battery voltage is OK
Low
Battery voltage is approaching EOL
(5-15% remaining capacity)a
EOL (End-of-Life)
Battery voltage is near depletion
(<5% remaining capacity)a
Schedule replacement surgery immediately.
In addition to the neurostimulator battery status, the programmer can
measure the battery voltage (volts), stimulation current (µamps), and
battery capacity.
It is recommended that stimulation current and impedance
measurements be taken after every programming session with your
patient. This information can be valuable at a later time if a
malfunction develops. The measurements can be used to
troubleshoot and isolate the problem.
For example, measurements that show a significant reduction in
stimulation current (or increase in impedance) can indicate a
fractured lead conductor, a loose setscrew, and so forth. Conversely,
a significant increase in stimulation current (or decrease in
impedance) can indicate shorted conductors, a break in lead
insulation, and so forth. In either case, it is very useful to know what
the settings were when the system was operating properly.
The battery capacity measurement calculates the voltage of the
neurostimulator battery and the percentage of battery capacity
consumed.
Note: The neurostimulator must be Off to perform this measurement.
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Battery Depletion
As the neurostimulator battery nears total depletion the output will
gradually decrease and then vanish completely when the
neurostimulator automatically shuts itself down.
Patients may experience a decrease in symptom
# Caution:
suppression as the battery nears total depletion. Patients
should be instructed to contact their clinician.
Notes:
■
When the neurostimulator battery reaches Low status, the
neurostimulator battery light on the therapy controller blinks
when the patient interrogates the device. Patients should be
instructed to contact their physician.
■
The clinician programmer calculates battery capacity
remaining, so the physician can schedule neurostimulator
replacement based on the patient settings and remaining
battery capacity1.
Power On Reset
As a safety feature, each time there is a temporary interruption in
battery output, the neurostimulator will automatically reset to zero
amplitude and output Off, the electrodes and case will reset to Off,
and the serial number will be lost. This could be caused, for example,
by use of an electrocautery tip near the neurostimulator or by
defibrillation. To restore stimulation, turn the neurostimulator On and
program the neurostimulator to the previously programmed
parameter values.
1
If the remaining battery capacity is 15% or less, schedule replacement surgery
immediately.
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How Supplied
X-Ray Identification
X-ray identification permits the determination of manufacturer and
neurostimulator model number. With standard x-ray procedures, the
code inside the connector block appears as white characters. The
Medtronic symbol identifies Medtronic as the manufacturer. For the
Kinetra Model 7428 Neurostimulator, the designated letters are NFD
(Figure 15).
Neurostimulator
Connector Block
Figure 15. X-ray identification location.
How Supplied
The Kinetra Model 7428 Neurostimulator package contains the
following:
■
One Model 7428 Neurostimulator
■
One Hex Wrench
■
Product Literature
Note: The contents of the inner package are STERILE.
The neurostimulator and accessories contained in the package are
intended for Single Use Only.
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Appendix A: Battery Longevity Reference Information
Appendix A: Battery Longevity Reference
Information
With the Kinetra neurostimulator, you can expect battery life to range
from months to years, depending on the parameters you have
selected for your patient and the patient’s use of the system.
Appendix A provides reference information that will assist you in
estimating Kinetra battery longevity prior to neurostimulator
internalization and maximize battery life during use. It contains the
procedure, tables and formulas needed to estimate battery longevity
plus tips for maximizing battery life. These estimates are based on
programmed parameters and correction factors for electrode
selection and expected usage time. However, actual battery life will
vary due to other factors such as impedance, changes in stimulation
requirements over time, amount of stimulation use, and stimulation
parameters selected within the programmed limits for amplitude,
rate, and pulse width.
Tips for Maximizing Battery Life
The following tips will help optimize Kinetra battery life:
■
Use the minimum number of active electrodes necessary for
effective stimulation.
■
Use bipolar stimulation. Keeping all other programmed
settings constant, changing to bipolar stimulation provides
longer battery life than unipolar stimulation.
■
Use the lowest effective settings and upper limits for amplitude,
rate, and pulse width.
Estimating Battery Life Prior to Neurostimulator
Internalization
Follow this procedure to estimate Kinetra battery life prior to
neurostimulator internalization. Use the worksheet on page 68 to
record settings and calculate longevity.
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Appendix A: Battery Longevity Reference Information
1. Determine the expected Program 1 operating parameters for
the neurostimulator, including Amplitude, Rate, Pulse Width,
number of active electrodes, cycle ON/OFF times, and hours
of stimulation per day.
2. Determine the Program 1 Energy Use (EU) from Table 8
(page 71) using the expected values for amplitude, rate, and
pulse width.
Notes:
■
Use the table values that are closest to the expected
values. Be aware that when values do not match, there will
be a discrepancy between calculated longevity estimates
and actual results.
■
Table 8 assumes neurostimulator usage of 24 hours per
day. If neurostimulator usage is different from that,
adjustments will be made in later calculations.
3. Determine the Program 1 Electrode Correction Factor (ECF)
from Table 9 (page 72) for the number of active electrodes.
Note: If selecting an electrode configuration for this program
with only one positive and only one negative electrode
(bipolar), you may skip step 3 because the Electrode
Correction Factor is 1.0.
4. Multiply the Program 1 Energy Use by the Program 1 Electrode
Correction Factor to obtain the Program 1 Factor (P1F).
5. Repeat steps 1 through 4 for Program 2 to obtain the
Program 2 Factor (P2F).
6. Add the Program 1 Factor and the Program 2 Factor to obtain
the Dual-Program Factor (DPF).
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Appendix A: Battery Longevity Reference Information
7. Determine the Usage Correction Factor (UCF) from the
following formula (the value will be between 0 and 1):
Usage Correction Factor = Usage Ratio x Cycling Ratio
[Usage Ratio = hours of stimulation (per day) ÷ 24 hours]
[Cycling Ratio = cycle On ÷ (cycle On + cycle Off)]
Notes:
■
If Cycling is not programmed, the formula becomes:
Usage Correction Factor = Usage Ratio
■
If using Continuous mode with 24 hours of stimulation, you
may skip step 7 because the Usage Correction Factor is
1.0.
8. Multiply the results of steps 6 and 7 to obtain the adjusted
Energy Use value:
DPF x UCF = adjusted Energy Use
9. Finally, take the adjusted Energy Use value and determine the
estimated battery longevity in years from Table 10 (page 73).
Example
Assume the patient’s neurostimulator will be programmed to these
settings:
Amplitude: Program 1 = 2.7 V; Program 2 = 3.0 V
Rate (for Programs 1 and 2) = 185 Hz
Pulse Width: Program 1 = 60 µsec; Program 2 = 120 µsec
Electrodes: Program 1 bipolar = 1 +, 2 –, remaining Off;
Program 2 bipolar = 5 +, 6 –, 7 – and 4 Off
Continuous mode
Hours of Stimulation = 16 hours
The Energy Use from Table 8 (page 71) would be 59 for Program 1
and 114 for Program 2.
The Electrode Correction Factor from Table 9 (page 72) would be 1.0
for Program 1 and 1.3 for Program 2.
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Appendix A: Battery Longevity Reference Information
Thus, the Program 1 Factor would be 59 x 1.0 = 59,
and the Program 2 Factor would be 114 x 1.3 = 148.2,
making the Dual-Program Factor 59 + 148.2 = 207.2.
The Usage Correction Factor would be:
Usage Ratio = 16 ÷ 24 = 0.66
Usage Correction Factor = Usage Ratio = 0.66
The adjusted Energy Use would be:
207.2 x 0.66 = 136.8
And the estimated battery longevity from Table 10 (page 73) would
be 5 years.
To show how small changes in parameter settings can have a big
impact on battery longevity, consider this alternate example:
All settings remain the same except the electrode configuration
for both programs is changed to unipolar (case +) with 2 active
electrodes.
The Electrode Correction Factor for both programs would be
2.8. This would result in an adjusted Energy Use of 319.7
instead of 136.8, and a longevity estimate of 2.3 years instead
of 5 years.
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Appendix A: Battery Longevity Reference Information
Battery Longevity Worksheet
Program 1 Energy Use (P1 EU)
Amp ______ V
Rate ______ Hz
PW ______ µsec
The Program 1 Energy Use (EU) from Table 8 on page 71 is: ______
Program 1 Electrode Correction Factor (P1 ECF)
If the electrode configuration for Program 1 is one positive and one
negative electrode, skip this step. Otherwise, the Program 1
Electrode Correction Factor (ECF) from Table 9 on page 72 is:
______
Program 1 Factor (P1F)
Compute the Program 1 Factor:
(P1 EU) _____ x (P1 ECF) _____ = _____ (P1F)
Program 2 Energy Use (P2 EU)
Amp ______ V
Rate ______ Hz
PW ______ µsec
The Program 2 Energy Use (EU) from Table 8 on page 71 is: ______
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Appendix A: Battery Longevity Reference Information
Program 2 Electrode Correction Factor (P2 ECF)
If the electrode configuration for Program 2 is one positive and one
negative electrode, skip this step. Otherwise, the Program 2
Electrode Correction Factor (ECF) from Table 9 on page 72
is: ______
Program 2 Factor (P2F)
Compute the Program 2 Factor:
(P2 EU) _____ x (P2 ECF) _____ = _____ (P2F)
Dual-Program Factor (DPF)
Compute the Dual-Program Factor:
(P1F) _____ + (P2F) _____ = _____ (DPF)
Usage Correction Factor
If using Continuous mode with 24 hours of stimulation, skip this step.
Otherwise, calculate the Usage Correction Factor as follows:
Hours of stimulation (per day): _____ hours
Cycle On time: _____
Cycle Off time: _____
Compute the Usage Ratio:
_____ hours of stimulation ÷ 24 hours = _____
And the Cycling Ratio:
_____ cycle On ÷ (_____ cycle On + _____ cycle Off) = _____
With the Usage Ratio (UR) and the Cycling Ratio (CR), compute the
Usage Correction Factor (UCF):
(UR) _____ x (CR) _____ = _____ (UCF)
Or if Cycling is not used:
(UR) _____ = _____ (UCF)
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Appendix A: Battery Longevity Reference Information
Longevity Estimate
Now calculate the adjusted Energy Use:
(DPF) _____ x (UCF) _____ = _____ (adjusted EU)
The estimated battery longevity from Table 10 on page 73 is:
__________ years
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Appendix A: Battery Longevity Reference Information
Table 8. Kinetra Neurostimulator Energy Use for 2 Active Bipolar
Electrodes per Program for 24 Hours/Day Usage.
Pulse Width
Amplitude
Rate
60
120
210
450
130
185
250
10
14
19
18
26
34
29
43
55
58
82
103
2.0
130
185
250
25
37
49
49
71
93
84
120
155
169
237
300
3.0
130
185
250
41
59
77
81
114
148
137
195
249
276
383
481
4.0
130
185
250
74
103
134
142
200
259
241
338
434
484
665
N/A
5.0
130
185
250
113
159
207
219
309
397
374
522
666
749
N/A
N/A
6.0
130
185
250
162
227
292
315
441
564
536
743
N/A
1073
N/A
N/A
7.0
130
185
250
222
312
400
432
603
774
735
1020
N/A
N/A
N/A
N/A
8.0
130
185
250
293
409
524
569
795
1013
968
N/A
N/A
N/A
N/A
N/A
9.0
130
185
250
376
523
664
731
1014
N/A
N/A
N/A
N/A
N/A
N/A
N/A
10.0
130
185
250
480
673
856
933
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1.0
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Appendix A: Battery Longevity Reference Information
Note: N/A in Table 8 refers to values that are not allowed by the
clinician programmer. Refer to “High Output Interlocks” on page 49.
Table 9. Kinetra Neurostimulator Electrode Correction Factor (ECF)
Electrode Configuration
Electrode Correction Factor
Bipolar
1 Negative, 1 Positive
1.0
1 Negative, 2 Positive
1.3
1 Negative, 3 Positive
1.5
2 Negative, 1 Positive
1.3
2 Negative, 2 Positive
1.8
3 Negative, 1 Positive
1.5
Unipolar
1 Negative, Case Positive
1.8
2 Negative, Case Positive
2.8
3 Negative, Case Positive
3.5
4 Negative, Case Positive
4.2
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Appendix A: Battery Longevity Reference Information
Table 10. Kinetra Neurostimulator Longevity Estimates
(Years) for Energy Use (EU).
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Appendix B: MRI and Activa Therapy
Appendix B: MRI and Activa Therapy
Introduction
It is important to read this appendix in its entirety before conducting
an MRI examination on a patient with any implanted Activa System
component. Contact Medtronic at 1-800-707-0933 if you have any
questions.
Due to the number and variability of parameters that affect MRI
compatibility, the safety of patients or continued functioning of Activa
Systems exposed to MRI cannot be absolutely ensured. MRI
systems generate powerful electromagnetic fields that can produce
a number of interactions with implanted components of the Activa
neurostimulation system. Some of these interactions, especially
heating, are potentially hazardous and can lead to serious injury or
death. However, with appropriate control measures, particularly with
respect to the selection of MRI parameters and RF coils, it is
generally possible to safely perform an MRI head scan on an Activa
patient. In addition, Activa System components can affect the MRI
image, potentially impacting the diagnostic use of this modality. The
following information describes the potential interactions and control
measures that should be taken to minimize the risks from these
interactions.
Implantation of an Activa Brain Stimulation
w Contraindication:
System is contraindicated for patients who will be exposed to
Magnetic Resonance Imaging (MRI) using a full body transmit
radio-frequency (RF) coil, a receive-only head coil, or a head
transmit coil that extends over the chest area. Performing MRI
with this equipment can cause tissue lesions from component
heating, especially at the lead electrodes, resulting in serious
and permanent injury including coma, paralysis, or death.
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Appendix B: MRI and Activa Therapy
w Warnings:
■
Do not conduct an MRI examination on a patient with any
implanted Activa System component until you read and
fully understand all the information in this manual. Failure
to follow all warnings and guidelines related to MRI can
result in serious and permanent injury including coma,
paralysis, or death.
■
In-vitro testing has shown that exposure of the Activa
neurostimulator system to MRI at parameters other than
those described in this guideline can induce significant
heating at the lead electrodes or at breaks in the lead.
Excessive heating may occur even if the lead and/or
extension are the only part of the Activa System that is
implanted. Excessive heating can result in serious and
permanent injury including coma, paralysis, or death.
■
MRI examinations of patients with an implanted Activa
System should only be done if absolutely needed and then
only if these guidelines are followed. MRI should not be
considered for Activa patients if other potentially safer
diagnostic methods such as CT, X-ray, ultrasound, or other
methods will provide adequate diagnostic information.
■
A responsible individual with expert knowledge about MRI,
such as an MRI radiologist or MRI physicist, must assure
all procedures in this guidelines are followed and that the
MRI scan parameters, especially RF specific absorption
rate (SAR) and gradient dB/dt parameters, comply with the
recommended settings, both for the pre-scan (tuning) and
during the actual MRI examination. The responsible
individual must verify that parameters entered into the MRI
system meet the guidelines in this appendix.
■
Do not conduct an MRI examination if the patient has any
other implants or limiting factors that would prohibit or
contraindicate an MRI examination.
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Appendix B: MRI and Activa Therapy
# Cautions:
■
The neurostimulator, especially those without filtered
feedthroughs such as the Itrel II Model 7424, may be reset
or potentially damaged when subjected to an MRI
examination. If reset, the neurostimulator must be
reprogrammed. If damaged, the neurostimulator must be
replaced.
■
MRI images may be severely distorted or image target
areas can be completely blocked from view near the
implanted Activa System components, especially near the
neurostimulator. If the MRI targeted image area is near the
neurostimulator, it may be necessary to move the
neurostimulator to obtain an image, or use alternate
imaging techniques. Do not remove the neurostimulator
and leave the lead system implanted as this can result in
higher than expected lead heating.
■
Carefully weigh any decision to perform magnetic
resonance imaging (MRI) examinations on patients who
require the neurostimulator to control tremor. Image
quality during MRI examinations may be reduced,
because the tremor may return when the neurostimulator
is turned off.
■
If possible, do not sedate the patient so that the patient
can provide feedback of any problems during the
examination.
■
Monitor the patient during the MRI examination. Verify that
the patient is feeling normal and is responsive between
each individual scan sequence of the MRI examination.
Discontinue the MRI immediately if the patient becomes
unresponsive to questions or experiences any heating,
pain, shocking sensations/uncomfortable stimulation, or
unusual sensations.
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Appendix B: MRI and Activa Therapy
Note: The MRI guidelines provided here may significantly extend the
MRI examination time or prevent some types of MRI examinations
from being conducted on Activa patients.
General Information on MRI
An MRI system produces three types of electromagnetic fields that
may interact with implanted neurostimulation systems. All three of
these fields are necessary to produce an MRI image. Each of these
fields can also produce specific but different types of interactions with
implanted neurostimulator systems. These fields include:
■
Static Magnetic Field. This is a steady state non-varying
magnetic field that is normally always ON, even when no scan
is underway. In a 1.5 Tesla MRI system, the static magnetic
field is approximately 30,000 times greater than the magnetic
field of the earth.
■
Gradient Magnetic Field. This is a low-frequency pulsed
magnetic field that is only present during a scan. The gradient
magnetic field can induce voltages onto the lead system that
may result in unintended stimulation or functional interactions
with the neurostimulator.
■
RF Field. This is a pulsed radio frequency (RF) field that is only
present during a scan. It can be produced by a variety of
transmission RF coils such as a whole body transmit coil or an
extremity coil such as a transmit/receive head coil. Only a
transmit/receive head coil should be used as the other RF coils
can expose more of the lead system to RF energy, thereby
increasing the risk of excessive heating and thermal lesions
possibly resulting in coma, paralysis, or death.
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Appendix B: MRI and Activa Therapy
MRI Interactions with Implanted Activa Systems
MRI/neurostimulation system interactions are various, and the risk to
the patient can range from minimal to severe. These interactions
include the following:
Heating – The MRI RF field induces voltages onto the lead system
that can produce significant heating effects at the lead electrodetissue interface or at the location of any breaks in the neurostimulator
lead system. Component heating from the MRI RF field is the most
serious risk from MRI exposure. Failure to follow these MRI
recommendations can result in thermal lesions possibly resulting in
coma, paralysis, or death.
Magnetic Field Interactions – Magnetic field interactions such as
force and torque effects are produced by the static magnetic field.
Any magnetic material will be attracted to the static magnetic field of
the MRI. The force and torque effects may produce movement of the
neurostimulator that can be uncomfortable to the patient, open a
recent incision, or both. Activa System components are designed
with minimal magnetic materials.
Induced Stimulation – Gradient magnetic fields may induce
voltages onto the lead system that may cause unintended
stimulation. The voltage of the induced stimulation pulses is
proportional to the time rate of change (dB/dt) of the gradient pulses,
the effective loop area created by the neurostimulator lead system,
and the location of the lead system with respect to the gradient coils
of the MRI.
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Appendix B: MRI and Activa Therapy
Effects on Neurostimulator Function – The static, gradient, and
RF fields of the MRI may affect the neurostimulator operation and
programming. The static magnetic field may cause the
neurostimulator to turn ON or OFF if the neurostimulator uses a
magnetically controlled switch that allows the patient to control
stimulation by the application of a handheld magnet. Additionally, the
MRI RF, static, and gradient fields may temporarily affect or disable
other functions, such as telemetry or stimulation pulses. Parameters
will need to be reprogrammed if the MRI causes a POR (Power On
Reset) of the neurostimulator.
Image Artifacts and Distortion – The neurostimulation system
components, particularly the neurostimulator, can cause significant
imaging artifacts and/or distortion of the MRI image, particularly if the
neurostimulator components contain magnetic material. The
neurostimulator can cause the MRI image to be completely blocked
from view (i.e., signal loss or signal "void") or severely distorted within
several inches of the neurostimulator.
MRI Procedure
Scope
These MRI/neurostimulator exposure guidelines apply to Activa
Systems comprising combinations of the following components:
■
Neurostimulator Models: Itrel II 7424, Soletra 7426,
Kinetra 7428
■
Lead Extension Models: 7495, 7482
■
Lead Models: DBS 3387, 3389
Supervision
A responsible individual such as an MRI radiologist or MRI physicist
must assure these procedures are followed. If the MRI is operated by
an MRI technician, it is strongly recommended the responsible
individual verifies that the MRI recommendations are followed.
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Appendix B: MRI and Activa Therapy
Preparation
Do the following prior to performing an MRI examination on an Activa
patient:
1. Inform the patient of the risks of undergoing an MRI.
2. Check if the patient has any other implants or conditions that
would prohibit or contraindicate an MRI examination. Do not
conduct an MRI examination if any are found.
3. Verify that all proposed MRI examination parameters comply
with the “MRI Operation Settings” on page 82. If not, the
parameters must be modified to meet these requirements. If
this cannot be done, do not perform an MRI.
4. If the patient has implanted leads but does not have an
implanted neurostimulator, perform the following steps:
a. Wrap the external portion of the leads/percutaneous
extensions with insulating material.
b. Keep the external portion of the leads/percutaneous
extensions out of contact with the patient.
c. Keep the external leads/percutaneous extensions straight,
with no loops, and running down the center of the head
coil.
5. If the patient has an implanted neurostimulator, perform the
following steps:
a. Review the neurostimulator with a clinician programmer
and print out a copy of the programmed parameters for
reference.
b. Test for possible open circuits by measuring impedance
and battery current on all electrodes in unipolar mode (see
Table 11). If an open circuit is suspected, obtain an x-ray to
identify whether the open circuit is caused by a broken lead
wire. If a broken lead wire is found, do not perform an MRI.
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Appendix B: MRI and Activa Therapy
Table 11. Measurement Values Indicating Possible Open Circuits
Neurostimulator
Impedance
Battery Current
Itrel II Model 7424
>2000 Ω
<10 µA
Soletra Model 7426
>2000 Ω
<10 µA
Kinetra Model 7428
>4000 Ω
<15 µA
An MRI procedure should not be performed in a
w Warning:
patient with an Activa System that has a broken lead wire
because higher than normal heating may occur at the break
or the lead electrodes which can cause thermal lesions.
These lesions may result in coma, paralysis, or death.
c. If the Activa System is functioning properly and no broken
lead wires are found, program the neurostimulator to the
settings provided in Table 12.
Table 12. Recommended Neurostimulator Settings for MRI
Parameter
Setting
Stimulation output
OFF (all programs)
Stimulation mode
Bipolar (all programs)
Amplitude
0 Volts (all programs)
Magnetic (reed) switch
Disabled (Kinetra Model 7428 only)
Other parameters
Do not change
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Appendix B: MRI and Activa Therapy
MRI Operation Settings
Prior to the MRI examination, a responsible individual such as an
MRI radiologist or MRI physicist must assure the examination will be
conducted according to the following MRI requirements. If standard
MRI pulse sequences will be used, they must meet these
requirements. If they do not, the pulse parameters must be adjusted
so that they comply with these requirements:
In-vitro testing has shown that exposure of the
w Warning:
Activa System to MRI under conditions other than described
in this guideline can induce excessive heating at the lead
electrodes or at breaks in the lead to cause lesions. These
lesions may result in coma, paralysis, or death.
■
Use only a 1.5 Tesla horizontal bore MRI (do not use open
sided or other field strength MRI systems).
■
Use only a transmit/receive head coil.
Implantation of an Activa Brain
w Contraindication:
Stimulation System is contraindicated for patients who
will be exposed to Magnetic Resonance Imaging (MRI)
using a full body transmit radio-frequency (RF) coil, a
receive-only head coil, or a head transmit coil that
extends over the chest area. Performing MRI with this
equipment can cause tissue lesions from component
heating, especially at the lead electrodes, resulting in
serious and permanent injury including coma, paralysis,
or death.
■
Enter the correct patient weight into the MRI console to assure
the head SAR is estimated correctly.
■
Use MRI examination parameters that limit the head SAR to 4/
10 (0.4) W/kg or less for all RF pulse sequences.
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Appendix B: MRI and Activa Therapy
w Warnings:
■
■
Ensure the SAR value is the value for head SAR.
Some MRI systems may only display SAR, whole
body SAR, or local body SAR. Make sure the value
being limited to 4/10 (0.4) W/kg is for head SAR.
Excessive heating may occur if the wrong SAR value
is used.
■
If MRI parameters must be manually adjusted after
the initial automatic MRI prescan, do not make any
adjustments that will increase the SAR value. Some
MRI machines may not automatically update the
displayed SAR value if manual adjustments are
made. This may lead to higher than expected
temperature increases in the Activa System,
particularly at the lead electrodes.
Limit the gradient dB/dt field to 20 Tesla/second or less.
Note: The recommendations provided are based on in-vitro testing
and should result in a safe MRI examination of a patient with an
implanted Medtronic Activa System. However, due to the many
variables that affect safety, Medtronic cannot absolutely ensure
safety or that the neurostimulator will not be damaged. The user of
this information assumes full responsibility for the consequences of
conducting an MRI examination on a patient with an implanted Activa
System.
Prior to the MRI Examination
Prior to the scan examination, the responsible individual must verify
the MRI examination parameters comply with these guidelines.
■
Patients with implanted Activa Systems should be informed of
the risks of undergoing an MRI.
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Appendix B: MRI and Activa Therapy
■
If possible, do not use sedation so the patient can inform the
MRI operator of any heating, discomfort, or other problems.
■
Instruct the patient to immediately inform the MRI operator if
any discomfort, stimulation, shocking, or heating occurs during
the examination.
During the MRI Examination
■
Monitor the patient both visually and audibly. Check the patient
between each imaging sequence. Discontinue the MRI
examination immediately if the patient is unable to respond to
questions or reports any problems.
■
Conduct the examination using only the MRI pulse sequence
that the MRI radiologist or physicist has confirmed meets the
MRI requirements above.
Post MRI Examination Review
■
Verify that the patient is feeling normal.
■
Verify that the neurostimulator is functional.
■
Reprogram the neurostimulator to pre-MRI settings.
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Glossary
Glossary
Amplitude – A measure of the electrical intensity delivered in a
stimulating pulse, measured in volts.
Interference – Anything that reduces the effectiveness of the
neurostimulator or a programming transmission.
Mode – The type of stimulation that can be programmed.
Parameter, Programmable – A specific function with an operating
range of selectable values (i.e., Rate, Pulse Width) that enables the
tailoring of neurostimulation therapy for a patient.
Pulse Width – A measure, in microseconds, of the duration of each
stimulating pulse.
Rate – A measure, in pulses per second (or Hz), that provides the
number of times stimulating pulses are delivered each second.
SoftStart/Stop Stimulation – The SoftStart/Stop feature that allows
stimulation to begin with a ramped output (e.g., it is designed to
prevent a sudden “burst” of stimulation when the neurostimulator
turns On normally). This is done by gradually increasing the
amplitude of the stimulating pulses up to the programmed value. The
SoftStart/Stop feature also causes a gradual decrease of the
amplitude of stimulation back down to zero when the neurostimulator
output is turned Off, or when the Off cycle begins.
Telemetry – A radiofrequency type of communication.
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Special Notice
Special Notice
Medtronic Neurostimulator kits consist of a neurostimulator and tools
to connect the neurostimulator to implantable extensions.
Neurostimulators are used with extensions, which are implanted in
the extremely hostile environment of the human body.
Neurostimulators may fail to function for a variety of causes, including
but not limited to, medical complications, body rejection phenomena,
or component failure. In addition, Neurostimulators and tools may be
easily damaged by improper handling or use. For tools, Medtronic
disclaims all warranties, both express and implied, including, but not
limited to, any implied warranty of merchantability or fitness for a
particular purpose. Medtronic shall not be liable to any person or
entity for any medical expenses or any direct, incidental or
consequential damages caused by any defect, failure or malfunction
of any tool, whether a claim for such damage is based upon warranty,
contract, tort or otherwise. No person has any authority to bind
Medtronic to any representation or warranty with respect to tools.
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220822001
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7428_EN.FM 12/15/03 4:06 pm
UC200xxxxxx EN
4.625 x 6 inches (117 mm x 152 mm)
220822001
Rev X
Medtronic Confidential
Pkg_R00a
7428_EN.FM 12/15/03 4:06 pm
UC200xxxxxx EN
4.625 x 6 inches (117 mm x 152 mm)
220822001
Rev X
Medtronic Confidential
Pkg_R00a
7428_ENbcv.fm 12/15/03 4:06 pm
UC200xxxxxx EN
4.625 x 6 inches (117 mm x 152 mm)
220822001
Rev X
Medtronic Confidential
package_R00a
7428_ENbcv.fm 12/15/03 4:06 pm
UC200xxxxxx EN
4.625 x 6 inches (117 mm x 152 mm)
Medtronic, Inc.
710 Medtronic Parkway
Minneapolis, MN 55432-5604
USA
Internet: www.medtronic.com
Tel. 1-763-505-5000
Toll-free 1-800-328-0810
Fax 1-763-505-1000
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© Medtronic, Inc. 2003
All Rights Reserved
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