Pacemaker complication

Nomenclature

• Position I
  • Chamber paced (A, V, or D (dual))
• Position II
  • Chamber sensed
• Position III
  • Response after Sensing
    • I = inhibited
    • T = triggered
    • D = Dual
• Position IV
  • Programmability
    • P = rate & output
    • M = multiprogramable
    • C = communicating
    • R = rate adaptive
    • O = none
• Position V
  • Arrhythmia Control
    • P = pacing
    • S = shock
    • D = dual (P+S)
    • O = none

Indications

1. Sinus Node Dysfunction-sinus bradycardia/arrest, sinoatrial block, chronotropic incompetence, a-fib.
2. Acquired AV block- 3rd degree block and 2nd degree type II
3. Chronic Bifascicular or Trifascicular block
4. After Acute MI-high mortality with persistent AV block post MI
5. Cardiac Resynchronization Therapy- Conduction delay (>150msec w/ mortality benefit) in chronic systolic heart failure further decreases EF, increases remodeling and increased MR.
6. Neurocardiogenic Syncope and Carotid Sinus Syndrome

Expected ECG Patterns

1. Absence of pacer artifact indicates intrinsic depolarization
2. Pacing artifacts preceding depolarizations indicate successful pacing and capture
3. Leads in RV apex produce LBBB pattern with appropriate discordance
4. New RBBB pattern may indicate lead in LV
5. Simulataneous depol of ventricles produces dominant R wave in V1

Plain Film Findings

1. Obtain PA/Lateral Films to confirm pulse generator, manufacturer, lead placement/number/integrity
2. R atrial lead J shaped(tip medially on AP) entering right atrial appendage
3. RV leads point downward with tip between left spine and cardiac apex--lateral XR shows inferior and anterior
4. Coronary sinus lead- courses posteriorly on lateral XR
5. Extra leads may be appropriately abandoned and capped
6. ICD component appears as thickened shock coil

Pacemaker Malfunction

Problems with pocket

1. Infection
   1. Most commonly Staphylococcus aureus or S. epidermidis
2. Hematoma
   1. Typically occurs shortly after placement

Problems with leads

1. Lead separation results in failure to capture
2. Lead dislodgment may cause thrombosis or myocardial rupture
3. Lead infection can cause severe sepsis

Failure to pace

1. Causes include battery exhaustion, wire fracture, or electrode displacement
2. Tissue reaction around electrode may make myocardium insensitive

Failure to sense

1. Voltages of patient's intrinsic QRS complex is too low to be detected
2. New intrinsic arrhythmia, AMI, electrolyte abnormalities, lead separation, battery depletion

Runaway Pacing

1. Physiologic electrical activity (T waves, muscle potentials)
2. External electromagnetic interference
3. Signals generated by interaction of different portions of the pacing system

Work-Up

1. CXR
2. ECG
3. Troponin
4. Interrogation

Management

• Use magnet to convert pacemaker to asynchronous mode if oversensing or runaway pacing