Download Pacemakers and AICD`s

Pacemakers
and
ICD’s
Dr.Gharibzadeh
Alaleh Rashidnasab
SCD most common cause of death
Sudden Cardiac Death
Sudden Cardiac Death
Death by an arrhythmia:
Bradycardia
Tachycardia
Atrial Fibrillation
Ventricular Fibrillation
Bradycardia
Sinus node discharges at a rate < 60 bpm
Decreased CO may occur
Tachycardia
Discharge rate from the sinus node is
increased and is > 100 bpm
Increased myocardial oxygen consumption
is associated with increased HR
Atrial Fibrillation
Total disorganization of atrial activity without effective
atrial contraction
Can often result in decrease in CO because of
ineffective atrial contractions and rapid ventricular
response
Goals are decreased in ventricular response and
conversion to sinus rhythm
Ventricular Fibrillation
Severe derangement of the heart rhythm
characterized on ECG by irregular undulations
of varying contour and amplitude
No effective contraction or CO occurs
If untreated, patient will die
Treatments
Drug therapy
Defibrillators
Pacemakers
ICDs(Implantable Cardioverter Defibrillator):
ICD Therapy consists of pacing, cardioversion, and
defibrillation therapies to treat brady and tachy
arrhythmias
Historical Perspective
1905 – Einthoven

Published first two human AV block using string
galvanometer
1958 – Senning and Elmqvist

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Asynchronous (VVI) pacemaker implanted by
thoracostomy and functioned for 3 hours
Arne Larsson
First pacemaker patient
Used 23 pulse generators and 5 electrode systems
Died 2001 at age 86 of cancer
Historical Perspective
1960 – First atrial triggered pacemaker
1964 – First on demand pacemaker (DVI)
1977 – First atrial and ventricular demand
pacing (DDD)
1980 – Griffin published first successful
pacemaker intervention for
supraventricular tachycardias
Historical Perspective
1981 – Rate responsive pacing by QT
interval, respiration, and movement
1994 – Cardiac resynchronization pacing
1998 – Automatic capture detection
Now

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Approximately 3 million with pacemakers
Approximately 1 million with ICD device
1980
Large devices Abdominal site
First human implants
Thoracotomy, multiple incisions
Primary implanter= cardiac surgeon
General anesthesia
Long hospital stays
Complications from major surgery
Perioperative mortality up to 9%
Nonprogrammable therapy
High-energy shock only
Device longevity  1.5 years
Fewer than 1,000 implants/year
Today
Small devices Pectoral site
First-line therapy for VT/VF patients
Treatment of atrial arrhythmias
Cardiac resynchronization therapy for HF
Transvenous, single incision
Local anesthesia; conscious sedation
Short hospital stays and few complications
Perioperative mortality < 1%
Programmable therapy options
Single- or dual-chamber therapy
Battery longevity up to 9 years
More than 100,000 implants/year
Evolution of ICD Therapy:
Pacemaker Basics
Provides electrical stimuli
to cause cardiac
contraction when intrinsic
cardiac activity is
inappropriately slow or
absent
Sense intrinsic cardiac
electric potentials
A Brief History of Pacemakers
ICD Basics
Designed to treat a cardiac tachydysrythmia
An external programmer is used to monitor and
access the device parameters and therapies for
each patient.
Performs cardioversion/defibrillation
 Ventricular rate exceeds programmed cut-off
rate
ATP (antitachycardia pacing)
 Overdrive pacing in an attempt to terminate
ventricular tachycardias
Some have pacemaker function (combo devices)
Implantable Defibrillators (1989-2003)
209 cc
62 cc
120 cc
49 cc
39.5 cc
80 cc
39.5 cc
80 cc
72 cc
54 cc
39.5 cc
38 cc
36 cc
Pacemaker and ICD Basics
Pulse Generators



Placed submuscularly
Connected to leads
Battery
Most commonly lithium-iodide type
Life span 5 to 8 years
Output voltage decreases gradually

Makes sudden battery failure unlikely
Pacemaker and ICD Basics
Asynchronous



Fixed rate
Impulse produced at a set rate
No relation to patients intrinsic cardiac activity
Pacemaker and ICD Basics
Synchronous

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Demand mode
Sensing circuit searches for intrinsic
depolarization potential
If absent, a pacing response is generated
Can mimic intrinsic electrical activity pattern of
the heart
Pacemaker Lead System
Endocardial leads placed via central
access

Placed in right ventricle and/or atria
Fixed to the endocardium via screws or
tines
Experimental pacing systems

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2 atrial leads (minimize afib)
Biventricular pacing
Pacemaker Indications
Absolute indications

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Sick sinus syndrome
Symptomatic sinus bradycardia
Tachy-brady syndrome
Afib with slow ventricular response
3rd degree heart block
Chronotropic incompetence
Inability to increase heart rate to match exercise
ICD Indications
Generally


Used in cases where there was a previous
cardiac arrest
Or, patients with undetermined origin or
continued VT or VF despite medical
interventions
Pacemaker Complications
EKG abnormalities due to



Failure to output
Failure to capture
Sensing abnormalities
Pacemaker Failure to Output
Definition

No pacing spike present despite indication to
pace
Etiology

Battery failure, lead fracture, break in lead
insulation, oversensing, poor lead connection,
“cross-talk”
Atrial output is sensed by ventricular lead
Pacemaker Failure to Capture
Definition

Pacing spike is not followed by either an atrial
or ventricular complex
Etiology

Lead fracture or dislodgement, break in lead
insulation, elevated pacing threshold, MI at
lead tip, drugs, metabolic abnormalities,
cardiac perforation, poor lead connection
Pacemaker Sensing
Abnormalities
Oversensing


Senses noncardiac electrical activity and is
inhibited from correctly pacing
Etiology
Muscular activity (diaphragm or pecs), EMI, cell
phone held within 10cm of pulse generator
Undersensing


Incorrectly misses intrinsic depolarization and
paces
Etiology
Poor lead positioning, lead dislodgement, magnet
application, low battery states, MI
ICD Complications
Similar to pacemaker complications

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Sensing and pacing failures
Inappropriate cardioversion
Ineffective cardioversion/defibrillation
ICD Sensing failures
Similar to pacmakers

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Oversensing
Undersensing
ICD Inappropriate Cardioversion
Most frequent complications
Provokes pain and anxiety in pts
Consider when

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Pt is in afib
Received multiple shocks in rapid succession
Etiology

Afib, T-wave oversensing, lead fracture, insulation
breakage, MRI, EMI
ICD Inappropriate Cardioversion
Treatment

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Magnet over ICD inhibits further shocks
Does NOT inhibit bradycardiac pacing
Note
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Some older devices produce beep with each QRS
If left on for >30 seconds, ICD disabled and continous
beep
To reactivate, lift off magnet and then replace for > 30
seconds, beep will return with each QRS
ICD Failure to Deliver
Cardioversion
Etiology

Failure to sense, lead fracture, EMI,
inadvertent ICD deactivation
Management

External defibrillation and cardioversion
Do not withhold therapy for fear of damaging ICD
If pt’s internal defibrillator activates during chest
compressions, you may feel a mild shock (no
reports of deaths related to this)

Antidysrhymthic medications
ICD Ineffective Cardioversion
Etiology

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Inadequate energy output
Rise in the defibrillation threshold
Lead fracture
Insulation breakage
Electromagnetic Interference
Can interfere with function of pacemaker
or ICD
Device misinterprets the EMI causing

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Rate alteration
Sensing abnormalities
Asynchronous pacing
Noise reversion
Reprogramming
Electromagnetic Interference
Examples

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Metal detectors
Cell phones
High voltage power lines
Some home appliances (microwave)
Electromagnetic Interference
Intensity of electromagnetic field
decreases inversely with the square of the
distance from the source
Newer pacemakers and ICDs are being
built with increased internal shielding
Future ICD Technology
Enhanced automaticity:

Device software that suggests programming options
to the clinician based on the patient’s history and
demographics
Continued reductions in device size:

Will require advancements in battery, capacitor and
circuitry technology and/or decreasing the delivered
energy output.
Future ICD Technology
Enhanced diagnostics:

Monitoring of the progression of both arrhythmias and
concomitant cardiac conditions
Enhanced lead technology:

Thinner leads with increased diagnostic capabilities,
e.g., pressure sensing.
Patient follow-up modifications:

Broadly available programmer technology that
enables remote transfer of data, reducing the need for
in-clinic visits.
Thank you