A potential complication of an ICD is?

• A. It may deliver a shock during ventricular fibrillation
• B. It reduces the heart rate to a dangerous level
• C. It disables the cardiac monitoring system temporarily
• D. It increases the risk of infection at implantation site

Answer: (A)

The key idea is understanding what an implantable cardioverter-defibrillator (ICD) does: it monitors heart rhythms and delivers a shock to terminate life-threatening arrhythmias like ventricular fibrillation. A potential complication discussed here is the device delivering a shock in the setting of a dangerous rhythm. While the shock is the therapeutic goal to save the patient, it represents a device-related adverse event that can occur and be distressing for the patient.

The other options don’t fit as well. The ICD does not purposefully reduce heart rate to a dangerous level; monitoring isn’t disabled by the device; and while infection at the implantation site is indeed a recognized complication, the option describing a shock during ventricular fibrillation aligns with the ICD’s fundamental function and its potential to cause an adverse event.