61-year-old woman with sudden electrical shocks
A 61-year-old woman presents to the emergency department after receiving four sudden electrical shocks from her implantable cardioverter-defibrillator. The discharges began while she was reaching overhead to restock high pantry shelves; she denies prior palpitations, chest pain, or lightheadedness. She takes carvedilol and lisinopril. Blood pressure is 126/78 mm Hg, pulse is 73/min, and the left pectoral pocket is nontender without erythema. While she is adjusting her sweater on the stretcher, another painful shock occurs; continuous telemetry demonstrates uninterrupted normal sinus rhythm before, during, and after the discharge. Serum potassium is 4.3 mEq/L. Which of the following is the most appropriate immediate next step in management?
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D
Explanation
Clinical Pearl:
Application of a clinical magnet over an implantable cardioverter-defibrillator generator temporarily suspends tachyarrhythmia detection and therapy delivery without disabling bradycardia pacing. This intervention provides immediate bedside cessation of inappropriate shocks caused by lead noise or oversensing while awaiting device interrogation.
Explanation:
The patient is experiencing inappropriate implantable cardioverter-defibrillator shocks caused by lead fracture or insulation breakdown, as evidenced by repetitive discharges provoked by arm and shoulder movement during continuous telemetry that confirms uninterrupted normal sinus rhythm. Relevant electrophysiology society guidance emphasizes that placing a clinical magnet directly over the device pulse generator is the definitive immediate bedside step to temporarily suspend tachyarrhythmia detection and shock delivery without impairing underlying bradycardia pacing. Initiation of an intravenous amiodarone infusion is indicated for electrical storm driven by recurrent ventricular tachyarrhythmias, but it is ineffective here because the patient has no underlying arrhythmia. Intravenous administration of a beta-adrenergic antagonist would be appropriate if inappropriate shocks were triggered by supraventricular tachycardia or sinus tachycardia crossing into the detection zone, but this patient maintains a normal resting heart rate of 73/min. Urgent surgical extraction and replacement of the transvenous lead represents the correct long-term mechanical solution, yet it is premature as an immediate action before shock delivery is first halted at the bedside. Delivery of synchronized external electrical cardioversion under sedation is contraindicated because the patient is in stable sinus rhythm, rendering external shocks clinically non-contributory and hazardous.
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