Similar to pacemakers, sensing problems, lead migration, and battery failure all occur in AICDs (usually within 3 months of implantation). A potential malfunction unique to the AICD is the inappropriate or lack of defibrillation of the device. Any of the above causes can lead to inappropriate therapy. The AICD may discharge inappropriately in response to rapid supraventricular rhythms such as atrial fibrillation, supraventricular tachycardia, or even sinus tachycardia. It also may fail to deliver appropriate shocks for v-tach or v-fib if the arrhythmia rate falls below the detection rate: as may be the case in patients on pharmacological rate therapy.
Kam PC. Anaesthetic management of a patient with an automatic implantable cardioverter defibrillator in situ. Br J Anaesth. 1997 Jan;78(1):102-6.