Inappropriate inhibition of biventricular pacing due to diaphragmatic myopotentials amplified by the selectable sensing filter

A 66-year-old man with a cardiac resynchronization therapy defibrillator (CRT-D: Quadra Assura 3367-40QC, St. Jude Medical Inc.) experienced asymptomatic intermittent inhibition of biventricular pacing, mainly after meals. All measured parameters of the true bipolar ventricular lead (Durata 7122Q, St. Jude Medical Inc.) were in the normal range and general provocative maneuvers could not reproduce any noise. Only Valsalva maneuvers succeeded in reproducing the noise, showing the typical signal morphology of extracardiac myopotentials (Panel A); thus, oversensing of diaphragmatic myopotentials was diagnosed. After turning off the low-frequency attenuation filter (LFA) of the CRT-D, neither inhibition of pacing for bradycardia nor inappropriate detection of tachyarrhythmias was observed, even at the highest sensitivity (Panel B).
Source: Europace - Category: Cardiology Source Type: research