Troubleshooting Implantable Cardioverter-Defibrillator Sensing Problems II

Abstract

In most patients, measurement of far-field R-wave amplitude in the supine position is adequate to evaluate far-field R-wave (Circ Arrhythm Electrophysiol. 2015;8:212-220.

Managing cross talk between a subcutaneous implantable cardioverter-defibrillator and a dual-chamber unipolar pacemaker system

“…This is related to the ventricular blanking period that is a nonprogrammable feature in the S-ICD and is 200 ms in the conditional zone and 160 ms in the shock zone. 3 Hence, in patients with paced ventricular complexes, a conditional zone that offers a longer post–ventricular blanking period has additional value besides discrimination for supraventricular tachycardia (which would not be an issue in this patient with complete heart block).…”

“…During that phase, algorithms that detect double counting and T-wave oversensing are also implemented. 3 …”

Clinical worsening due to inappropriate automatic mode switch during biventricular pacing: What is the mechanism?

“…Changing the RA/RV lead position might be required when recognized during the implant. When FFRWO is encountered later on follow‐up, like our case, the options are 3,4,5 : Increasing the PVAB, so that the "As/Ar" falls within blanking period (hence annotated as Atrial sensing in blanking PVAB [Ab]) and not classified as atrial beat. This strategy, however, does not help when at the rare instances far‐field is sensed even before right ventricular pacing (when LV is pre‐excited) 6 …”

“…If atrial sensing polarity is "unipolar," switching it to "bipolar" can be useful at times. Changing the pacing polarity of the LV channel can be useful as the change of directionality of the vector might help sometimes. In selected cases, increasing the AMS detection rate (e.g., making it 200‐220 bpm) might prevent AMS as calculated rate may not exceed, unless that patient develops a sustained sinus/atrial tachycardia (>100‐110 bpm). If there is considerable safety margin (>50%) with good P waves, like our case, decreasing atrial channel sensitivity (by increasing the programmed sensitivity value, that is, the "fence height" of sensing) can help to overcome the issue. In some devices, algorithms like PVAB partial+ (Medtronic Ltd., MN) might help by selectively reducing atrial channel sensitivity for a defined duration after each Vp/Vs event (desensitization window), although not applicable in our case with St. Jude Device. FFRWs may also be obviated by applying an algorithm that identifies 2:1 AF or specifically recognizes FFRWs based on the combination of a 2:1—atrioventricular pattern combined with additional A‐A and A‐V interval criteria 5,7 …”

“…FFRWs may also be obviated by applying an algorithm that identifies 2:1 AF or specifically recognizes FFRWs based on the combination of a 2:1—atrioventricular pattern combined with additional A‐A and A‐V interval criteria 5,7 …”