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Exercise Management
Pacemakers and Implantable
Cardioverter Defibrillators
Chapter 10
Exercise Management
Overview of the Pathophysiology
• Loss of the normal sequence of atrial and
ventricular filling and contraction can result in:
– deterioration of hemodynamics, and
– significant symptoms of cardiovascular compromise at
rest and during exercise.
• Pacing equipment can normalize these
aberrations and improve symptoms while
enhancing exercise performance
Exercise Management
•Individuals who cannot increase their heart
rate in response to increased metabolic
demand usually have sinus node dysfunction
and may require cardiac pacing.
•Other individuals who have life-threatening
ventricular arrhythmias are sometimes
candidates for an implantable cardioverter
defibrillator (ICD).
Exercise Management
Pacing Terminology
Chronotropic incompetence
The inability to augment the heart rate to an
appropriate level with increases in metabolic
demand. It is confirmed by peak exercise HR
<85% of age-predicted max, or failure to
reach > 80% of HRR during any stage of an
exercise test.
Exercise Management
Symptomatic bradycardia
Symptoms directly attributable to a slow HR
(< 50 bpm) include activity intolerance,
transient dizziness, lightheadedness, and
complete or near loss of consciousness
(syncope), SOB and weak pulse.
Exercise Management
Pacemaker syndrome
• Constellation of clinical signs and symptoms
– A consequence of the inadequate timing of atrial and ventricular
contraction.
– Most typically results from single chamber (i.e., ventricular) pacing
with loss of atrioventricular synchrony and retrograde atrial
activation.
• Symptoms result from a reduced cardiac output, negative
atrial contribution to stroke volume, or both.
• Symptoms include lethargy, fatigue, lightheadedness,
hypotension, shortness of breath, syncope, neck pulsations,
and. impaired exercise capacity.
Exercise Management
Sudden cardiac death syndrome
A clinical scenario during which the person
experiences loss of consciousness usually due to a
ventricular tachyarrhythmia, usually ventricular
tachycardia and /or ventricular fibrillation.
Unless there is prompt restoration to normal
rhythm, death ensues. Severe bradycardia and
asystole can also account for sudden death in a
minority of cases.
Requires use of AED or ICD for return to NSR.
Exercise Management
Rate-adaptive pacemakers
Pacemakers equipped with sensors that
allow adaptation of the pacemaker's rate
commensurate with increases in demand
(i.e.,exercise). These units utilize various
types of sensors, including those that
respond to physiological, mechanical, or
electrical signals. This facilitates pacing in a
more physiologic manner.
Exercise Management
Tiered therapy
ICDs that utilize antitachycardia pacing,
shock therapies, and bradycardia safety
pacing in a step-wise approach to the
treatment of life-threatening ventricular
arrhythmias.
Exercise Management
Pacemakers
Indications for Pacemaker Implantation
• Sick sinus syndrome with symptomatic
bradycardia
• acquired AV block
• persistent advanced AV block after
myocardial infarction.
Exercise Management
Pacemakers are categorized by a standardized
code: (for typical placement and function, see p. 80)
• the first letter represents the chamber paced
• the second is the chamber sensed
• the third connotes the response to a sensed
event.
• the fourth position is utilized to indicate that the
pacemaker has rate-response capabilities.
Exercise Management
Pacemakers are categorized by a standardized
code:
For example, if [ V V I R ]is the abbreviation
used, then
• the ventricle (V) is the chamber being paced and
sensed.
•when the pacemaker senses a normal ventricular
contraction, the pacemaker is inhibited (I).
•The R indicates that the pulse generator is rate
responsive during exercise.
Exercise Management
Dual Chamber Pacemaker (DDDR)
• paces and senses both the atrium and
ventricle
• triggers or inhibits dependent upon normal
conduction signal that is above the
programmed rate cutoff on the pacemaker
• is considered the “optimal” pacemaker type
for those individuals who have normal SA
node function
Exercise Management
Implantable Cardioverter Defibrillators (ICD)
• are utilized to electrically terminate life
threatening ventricular tachyarrhythmias
• when a tachyarrhythmia is detected,
preprogrammed therapies are sent back to
terminate the arrhythmia.
• ICDs can pace-terminate an arrhythmia
and/or deliver electric cardioversion /
defibrillation shocks.
Exercise Management
Effects on the Exercise Response
Pacing devices
• Patients with pacing devices benefit from an
improved heart rate response to exercise.
• Inadequate heart rate responses to exercise can
be improved with pacemaker technologies.
Exercise Management
Effects on the Exercise Response
ICDs
Patients are at risk of receiving inappropriate shocks during
exercise if
• the heart rate exceeds the programmed threshold
rate for therapy
• the person develops an exercise-induced supraventricular
tachycardia.
Thus, patients with ICDs should be closely monitored during
exercise to ensure that their heart rate does not approach
the activation rate for the device.
Exercise Management
Effects of Exercise Training
• Recent technologic advances have dramatically
advanced pacemaker function to the point where
pacemakers can nearly mimic normal cardiac
function, both at rest and during exercise.
•These advances allow cardiac supply to meet the
increase in cardiac demand.
•Exercise heart rate thresholds on the ICD must be
set above (10%) the upper end of the exercise
heart rate
•Heart rate must be closely monitored during the
entire exercise session
Exercise Management
Recommendations for Exercise Testing
• Exercise testing may be used to determine
the effectiveness of rate-responsive
pacemakers
•LLGXT and small incremental protocols are
appropriate.
•See Table 10.1, (slide follows) note exercise
endpoints, especially for peak HR with ICD’s
and blood pressure response to exercise.
Exercise Management
Recommendations for Exercise Testing
• Exercise HR must stay below the ICD HR
threshold
•Radionuclide testing or stress echo may
improve the test sensitivity (also you will
need to be aware of underlying CV
pathologies)
•See Table 10.1, (slide follows) note exercise
endpoints, especially for peak HR with ICD’s
and blood pressure response to exercise.
Exercise Management
Exercise Management
Recommendations for Exercise Programming
• Before an exercise program begins, the upper training
heart rate should be established and documented.
• Activities should be selected so that the intensity can be
carefully regulated during exercise.
• Because some upper body movement may dislodge
implanted leads, upper body exercises are not advised
initially for people with pacemakers (resistance training
should not begin until 4-6 wks post-implantation).
• The upper exercise training intensity must be set below
the person's ischemic threshold and must not approach a
heart rate causing activation of the ICD
Exercise Management
Recommendations for Exercise Programming
Specific ICD information should include:
• ICD detection threshold in bpm
•Whether if device is for V fib or V tach
•How quickly should HR increase
•What is the sustained VT setting (how long will
the episode last before a therapy is delivered?)
•What is the specific type of ICD therapy
(Pacing, shock, etc..)?
•See Exercise Programming, Table 10.2, p.82,
(next slide)
Exercise Management
Exercise Management
End of Presentation