Nonsustained lead noise alert associated with repeating pattern of signals on the ventricular channel: Is there true concern for lead malfunction?

Abstract

Case summary A 25-year-old woman, relisted for cardiac transplantation, presented with symptoms of syncope and abdominal pain that correlated with periods of complete heart block on monitoring. Her past medical history included congenital Ebstein anomaly, Blalock-Taussig shunt, and eventual orthotropic biatrial cardiac transplant 15 years before the current presentation. She had persistent sinus tachycardia due to failing transplant secondary to allograft vasculopathy. Her ejection fraction was preserved with elevated filling pressures. There was no evidence of rejection on endomyocardial biopsy. Previous electrophysiologic evaluation revealed she had no residual donor-to-recipient atrial conduction, no retrograde ventriculoatrial (VA) conduction, or any other inducible arrhythmia that may have contributed to her functional deterioration. She had dual nodal physiology and conduction down the slow pathway with a long PR interval with heart rates 4120 bpm. She subsequently underwent dual-chamber implantable cardioverter-defibrillator (ICD) placement (St. Jude Medical [SJM] Fortify Assura, St. Paul, MN) for complete heart block associated with syncope. Pacing mode was programmed to DDDR with a base of 80 bpm. Hysteresis rate was set at 60 bpm. Paced atrioventricular (AV) delay was programmed to 225 ms with postventricular atrial refractory period (PVARP) of 275 ms. Lead impedances and sensing and pacing parameters were within normal limits. The alert shown in Figure 1A was received on the Merlin (SJM)