Pacemaker

Aka: Pacemaker

1. See Also
   1. Implantable Defibrillator (AICD)
   2. Cardiac Resynchronization Implantable Device
   3. Left Ventricular Assist Device (LVAD)
2. Indications: Permanent Pacemaker in AV Block
   1. Class I Indications (helpful)
      1. Sick Sinus Syndrome with symptomatic Bradycardia
      2. Second Degree AV Block with symptomatic Bradycardia
      3. Third Degree AV Block with one associated condition
         1. Symptomatic Bradycardia
         2. Documented Asystole (3 seconds or greater)
         3. Catheter ablation of the AV junction
         4. Neuromuscular disorder with AV Block
            1. Myotonic muscular disorder
            2. Kearns-Sayre Syndrome
            3. Erb's Dystrophy (limb-girdle)
            4. Peroneal muscular atrophy
   2. Class IIa Indications (probably helpful)
      1. Sick Sinus Syndrome with rate <40 bpm
         1. Symptom association with Bradycardia unclear
      2. Asymptomatic third degree AV Block
      3. Asymptomatic Type II second degree AV Block
      4. Asymptomatic Type I AV Block at His level
      5. First degree AV Block and Pacemaker syndrome symptoms
   3. Class IIb Indications (Possibly helpful)
      1. Sick Sinus Syndrome with chronic awake rate <30 bpm
         1. Minimally symptomatic patients
      2. Marked First Degree AV Block (>0.3 seconds) with CHF
   4. Class III Indications (Not helpful, possibly harmful)
      1. Asymptomatic Bradycardia due to medication
      2. Asymptomatic First Degree AV Block
      3. Asymptomatic Type I AV Block limited to supra-His
      4. Transient AV Block secondary to resolving condition
         1. Drug toxicity
         2. Lyme Disease
3. Description: Pacemaker Codes
   1. Position 1 (chamber paced)
      1. V - Ventricle
      2. A - Atrium
      3. D - Dual (A and V)
      4. O - None
   2. Position 2 (chamber sensed)
      1. V - Ventricle
      2. A - Atrium
      3. D - Dual (A and V)
      4. O - None
   3. Position 3 (response to sensing)
      1. V - Triggered
      2. I - Inhibited
      3. D - Dual (T and I)
      4. O - None
   4. Position 4 (programmable functions and rate modulation)
      1. P - Programmable rate and output
      2. M - Muti-programmability of rate, output, sensitivity
      3. C - Communicating via telemetry
      4. R - Rate modulation
      5. O - None
   5. Position 5 (anti-tachyarrhythmia)
      1. P - Pacing (anti-tachyarrhythmia)
      2. S - Shock
      3. D - Dual (P and S)
      4. O - None
4. Types: Pacemaker Selection for Sinus Node Dysfunction
   1. No signs or future risks for impaired AV conduction
      1. Rate response: Rate-responsive atrial pacer (AAIR)
      2. No rate response: Atrial Pacemaker (AAI)
   2. Impaired AV Conduction and no AV synchrony needed
      1. Rate response: Rate-responsive dual chamber (DDDR)
      2. No rate response: Ventricular Pacemaker (DDD)
   3. Impaired AV Conduction and AV synchrony needed
      1. Tachyarrhythmia (e.g. PSVT)
         1. Rate response: Rate-responsive dual chamber (DDDR)
         2. No rate response: Dual chamber Pacemaker (DDD)
      2. No Tachyarrhythmia
         1. Rate response: Rate-responsive dual and mode switch
         2. No rate response: Dual chamber with mode switching
5. Precautions
   1. Magnetic field exposure
      1. Pacemakers typically switch to asynchronous pacing at a set rate on exposure to magnetic field
      2. MRI scans are contraindicated
         1. Exception: Recent devices as of 2012 that have been designed MRI safe (with limitations)
      3. Cell phones should be held on the opposite side of body, away from Pacemaker
         1. Theoretical risk only
      4. Magnets may be helpful in some emergency settings (e.g. applied to AICD that is delivering inappropriate shocks)
   2. Battery life remaining in Pacemaker
      1. Pacers are interrogated to determine remaining battery life
      2. When battery life drops below ERI (Elective replacement indicator), Heart Rate will be be fixed at a manufacturer-set rate
      3. When battery life drops below EOL (End of life), Heart Rate will be fixed at a different fixed manufacturer-set rate
   3. External Defibrillation and cardioversion
      1. Electrical shock may theoretically damage Pacemaker
      2. Emergency Defibrillation may be performed without regard to Pacemaker
      3. Avoid applying elective cardioversion pads directly over Pacemaker
6. Management: Troubleshooting a malfunctioning Pacemaker
   1. Pacemaker problems
      1. Dislodged Pacemaker lead
      2. Pacemaker syndrome
         1. Loss of atrial capture with only ventricle paced
         2. Presents with retrograde pulsations into the neck and secondary Heart Failure or Hypotension
      3. Runaway Pacemaker syndrome
         1. A damaged Pacemaker theoretically could sporadically increase paced rates at well above 100
         2. Would require emergent removal of the device
      4. Inadequate pacer energy
   2. Interrogate the Pacemaker
      1. Pacemaker programming head is placed directly over Pacemaker and push interrogate button
      2. Identify the patient's underlying rhythm
         1. Are the pacer spikes atrial or ventricular?
         2. Is the rhythm Pacemaker dependent?
            1. If uncertain, Pacemaker rate can be slowed to see if patient's rate also drops
      3. Can the Pacemaker sense the heart rhythm?
      4. Can the Pacemaker pace the heart?
      5. Are there other rhythm problems?
         1. Some Pacemakers can store abnormal rhythm events (e.g. VT runs) with a date-time stamp
      6. Is the Pacemaker programmed correctly?
   3. Evaluation measures
      1. Electrocardiogram
      2. Chest XRay
         1. May identify misplaced or damaged lead
   4. Data to have available when communicating with Cardiology about a patient with possible Pacemaker-related problem
      1. Is the device a Pacemaker or Defibrillator?
      2. How many wires to heart are present?
      3. When and where was the device implanted?
7. Complications: Pacemaker infection
   1. Pacemakers must be removed for either early or late infections
   2. Early infection
      1. Presents with localized erythema, swelling, purulent discharge within weeks of Pacemaker placement
      2. Infections occur more often in Diabetes Mellitus, post-placement hematoma or with Defibrillator placement
   3. Late infection
      1. Presents with insidious, slowly developing infection; may only demonstrate an overlying Skin Erosion
      2. Infections occur more often after Pacemaker manipulations (with 1-3% risk with each manipulation)
8. References
   1. Jones and Orman in Majoewsky (2012) EM:Rap 12(5): 4-6
   2. Bernstein (1987) Pacing Clin Electrophysiol 10:794-9
   3. Gregoratos (1998) J Am Coll Cardiol 31:1175-209
   4. Gregoratos (2005) Am Fam Physician 71:1563-70