His Bundle Pacing via the Atrial Port of a Dual‐Chamber ICD: Programming Solution for Undersensing

BACKGROUND: His-bundle pacing connected to the atrial port of a dual-chamber ICD may lead to sensing failure and unsafe pacing. CASE SUMMARY: A 67-year-old man with permanent atrial fibrillation, alternating rapid and slow ventricular rates despite medication, symptomatic pauses longer than 6s, and a dual chamber ICD (His lead in the RA port; DF4 lead in the RV port) presented with palpitations. ECG and 24-hour Holter demonstrated intermittent His-channel undersensing with pacing on the T-wave peak. Interrogation showed small His electrograms followed by a prominent, constant ventricular far-field signal on the atrial channel. We turned off far-field protection after V-sense, intentionally used the ventricular far-field signal for sensing of His lead, and disabled related discrimination algorithms. CONCLUSION: A dual-chamber ICD with a His-bundle pacing lead may be associated with complex programming challenges, and targeted reprogramming can avoid lead revision or reimplantation.