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More than 75% implantable cardiac defibrillators (ICDs) are placed as a prophylactic measure for risk of sudden cardiac death (SCD) from specific disease states (e.g., HCM).


Many patients who receive a pacemaker for specific causes (see chapter 18) will have dual-function devices, also capable of defibrillation.


All implanted devices, ICD as well as pacemakers, are contraindicated in the MRI suite.


  • Prior cardiac arrest
  • NYHA class II or III nonischemic dilated CM, EF <30%
  • Prior MI (>40 days), EF <30%
  • Structural heart disease or inherited arrhythmia syndromes (long QT, Brugada):
    • Genetic disorder that is characterized by right bundle branch block, ST segment elevation in V1 to V3, and sudden death in patients with a structurally normal heart. EKG pattern with J point elevation
  • Syncope of unknown origin


  • Larger than pacemakers; therefore, often implanted under pectoralis muscle under GA (VF induction for testing)
  • Functions:
    • Overdrive pacing if monomorphic VT
    • Cardioversion or defibrillation if polymorphic VT or VF
    • Pacing function if pause (especially after cardioversion or defibrillation)
  • Four-letter code

Table Graphic Jump Location
Table 19-1 Code for ICD Devices

  • Rarely absence of response to VT/VF
  • Most often inappropriate electric shock
  • Causes:
    • Electrocautery (Bovie) essentially
    • RF ablation
    • Lithotripsy
    • ECT
    • Electrolyte/acid–base abnormalities
    • Medications:
      • Succinylcholine (fasciculations can inhibit PM or trigger ICD; not an absolute contraindication)
    • Other (rare): orthopedic saw, telemetric devices, mechanical ventilators, nerve stimulator (anesthesia or SSEP/MEP)


  • Determine type of ICD functions through manufacturer’s identification card and/or ID bracelet
  • Determine battery function and when the device was last interrogated
  • Turn ICD functions off:
    • Interrogation and disabling of device by company representative or qualified personnel
    • If not possible, magnet application to be kept on for duration of procedure (usually done in OR):
      • ICDs manufactured by CPI are deactivated after 30 seconds of magnet application (beeping sound) but magnet reapplication can reactivate device; therefore, do not use magnet (except in emergency) if type/brand of device not known
      • Reevaluation of device postmagnet therapy


  • Need to monitor HR by another device than EKG: pulse oximeter and/or A-line
  • Deactivate device (if not done preoperatively in holding area):
    • Defibrillator function
    • Antitachycardia function
  • Place external defibrillator pads connected to defibrillator:
    • Anterior/posterior position, not apex/right upper thorax
    • Not overlying implanted device
  • Place cautery return pad as far from ICD as possible:
    • Advise surgeon to use short <1 second bursts of electrocautery
    • Use bipolar cautery if possible, regardless of device deactivation, to minimize risk of device damage from EMI
  • Avoid/correct any cause of dysrhythmia: electrolyte imbalance, ischemia, hypovolemia
  • If malfunction:
    • Turn off all electrical devices
    • If VT/VF without ICD response, use external defibrillator
    • If inappropriate shocks, evaluate clinical tolerance:
      • If poorly tolerated, apply magnet
      • Otherwise, have ...

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