Cardiovascular Pacemakers: Implications for the Physical Therapist

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Cardiovascular PacemakersImplications for the
Physical Therapist

• Sean Collins, PT, ScD, CCS

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Why a pacemaker?Synchrony of the Atria
Ventricles (AV Synchrony) is important for both
diastolic systolic function
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Indications for Pacemaker

• Class I
• 1. Sinus node dysfunction with documented
  symptomatic bradycardia
• 2. Symptomatic chronotropic incompetence (failure
  to increase HR with exercise or increased
  metabolic demand)
• 3. 3 and advanced 2 AV block associated with
  any of the following
• Arrhythmias that require drugs resulting in
  symptomatic bradycardia
• Sinus pauses gt 3 seconds
• Asymptomatic escape rate lt 40bpm while awake
• 4. 3 or 2 AV block with associated symptomatic
  bradycardia
• 5. Type II 2 AV block with wide QRS, regardless
  of symptoms

From K Dias, Maryville U
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Indications for Pacemaker

• Class IIa
• 1. Syncope of unexplained origin when major
  abnormalities of sinus node function are
  discovered or provoked during EP studies.
• 2. Asymptomatic 3 AV block with an awake
  ventricular rate gt 40bpm
• 3. Asymptomatic type II 2 AV block

From K Dias, Maryville U
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Pacemaker Codes
From K Dias, Maryville U
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Pacemaker ConfigurationsVOO
Indications Temporary mode some-times used during
surgery to prevent interference from
electrocautery
From K Dias, Maryville U
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Pacemaker ConfigurationsVVI
Indications The combination of AV block and
chronic atrial arrhythmias (particularly atrial
fibrillation).
From K Dias, Maryville U
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Pacemaker ConfigurationsAAI
Indications Sick sinus syndrome in the absence of
AV node disease or atrial fibrillation.
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Pacemaker ConfigurationsVDD
Indications AV block with intact sinus node
function (particularly useful in congenital AV
block).
From K Dias, Maryville U
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Pacemaker ConfigurationsDDD
Indications 1. The combination of AV block and
SSS. 2. Patients with LV dysfunction and LV
hypertrophy who need coordination of atrial and
ventricular contractions to maintain adequate CO.
From K Dias, Maryville U
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Rate Response

• Rate responsive (also called rate modulated)
  pacemakers provide patients with the ability to
  vary heart rate when the sinus node cannot
  provide the appropriate rate
• Rate responsive pacing is indicated to prevent
  chronotropic incompetence (heart rate cannot
  reach appropriate levels during exercise or to
  meet other metabolic demands)

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Rate Response

• Why does heart rate respond?
• Allostatic demands
• Metabolic fluctuations
• BP buffering
• Need for variation in Cardiac Output
• Ashbys Law of Requisite Variety

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Rate Responsive Pacing

• Cardiac output (CO) is determined by the
  combination of stroke volume (SV) and heart rate
  (HR)
• SV X HR CO
• VO2 CO x (a-v)O2 difference
• Sustainable workload a max VO2
• (BP CO x Peripheral Resistance)

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Changes in cardiac output attempt to match
metabolic requirements
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Rate Responsive Pacing

• SV reserves can account for increases in cardiac
  output of up to 50
• HR reserves can nearly triple total cardiac
  output in response to metabolic demands

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Assessing Rate Response

• Pulse
• ECG
• HR monitor
• Pulsed Oximeter
• Auscultation
• Consider not only current (point estimate) rate
  by temporal changes
• 60 second rate first/last 10 seconds
• Consider rhythm if abnormal, ECG

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Rate Response Sensors

• Activity sensors detect physical movement and
  increase the rate according to the level of
  activity
• Physiological Sensors
• Minute ventilation
• QT Interval Sensors

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Sensor Implications

• HR response depends on sensor function in total
  demand pacing
• If Activity based seated exercise, bicycling,
  may not induce a HR response
• Assess response with warm up
• Assess relationship between rate response and
• Symptoms
• Blood Pressure
• If there are questions observe the ECG with
  exercise

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PT Pacer Implications

• Is the pacer working as it should?
• If not as it should, document observations and
  measures speak with cardiologist
• If it is working as it should is it optimal?
• If not optimal, document observations and
  measures speak with cardiologist
• Incorporate presence of pacer into evaluation
  (prognosis) and intervention (how does the pacer
  respond and enable increased workload)

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For your records --
From Collins Cahalin, 2005
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• Case I
• 56 yo Male s/p transplant and rejection
  worsening LV function (EF 36 to 18 in 10
  months) DDDR Pacemaker
• HR started declining as he reached symptom
  limited workloads
• Associated with drops in SPB
• Started occurring at lower absolute workloads
• What to do?

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Case II 80 yo Female, h/o CHF, AFib, CAD, et al
VVIR pacemaker -s/p long acute care stay -very
weak, de conditioned -experienced symptom
limiting fatigue soon after starting ambulation
(within 15 seconds) no increase in SBP, no
increase in HR c/o fatigue SOB What to do?
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Case III 72 yo Male, s/p PTCA, SOB, Fatigue with
minimal exertion -Independent with all BADLs
and IADLs 3 days ago -limited after short
distances of ambulation (otherwise
independent) What to do?