Ventricular Activation Sequence during Left Ventricular Pacing Promotes QRS Complex Oversensing in the Atrial Channel

Abstract

Oversensing artifacts in the atrial channel are likely caused by depolarization of the basal part of the right ventricle. The novel mechanism of QRS oversensing outside PVARP, caused by a reversed ventricular activation sequence during LV-only pacing, may be important in some CRT patients.

Pacemaker‐mediated tachycardia: What is the mechanism?

“…This is confirmed by the observation that despite a QRS to pacing spike interval of 220 ms, the “As” to “Vp” event markers interval (Figure ) is 120 ms, equal to the sensed AV delay interval, and the “As” event marker corresponds with the end of the QRS in the surface ECG lead (Figure ). This situation closely resembles previously described relationships between the ventricular activation sequence during ventricular pacing and the predisposition for ventricular oversensing …”

“…This situation closely resembles previously described relationships between the ventricular activation sequence during ventricular pacing and the predisposition for ventricular oversensing. 2 In consequence, a combination of ventricular oversensing, lead dislodgement, first-degree AV block with PR interval > PVARP, PVAB, and possibly sensing assurance function created a milieu for a far-field dualchamber pacemaker orthodromic ELT. Interestingly, such an ELT type was not included in the ELT nomenclature.…”

Use of an Atrial Lead with Very Short Tip-To-Ring Spacing Avoids Oversensing of Far-Field R-Wave

“…Far-field R-wave signals remained stable in their coupling intervals and amplitudes during a three months observation period in a previous study [8]. Considering the pathophysiology of far-field R-wave formation [24], we believe that our results are likely to be valid also in a mid-term follow-up provided that major atrial and ventricular remodeling or cardiac disease progression does not occur.…”

Intermittent Irregular Pacemaker‐Mediated Tachycardia

“…In particular, the “VF” event measured in excess of 650 ms from the previous paced event, making this oversensed event highly unlikely to be related to oversensing of the QRS complex associated with the change in ventricular activation. Nonetheless, one should be cognizant of the unintended consequences of LV‐only pacing in triggering ELT by alterations in PVARP due to triggered pacing, alteration in ventricular activation and resultant atrial/ventricular oversensing, and prolonged VA conduction time as in this case.…”

“…Markers in Figure are suggestive of oversensing of the terminal part of the QRS complexes. Indeed, the change in ventricular activation with LV pacing only (due to loss of RV capture) can result in oversensing . However, the two consecutive oversensed events in Figure —marked as “PVC” and “VF” events—are unrelated to the previous QRS complexes (note the apparent QRS complex on the ECG channel was in fact an artifact; there is no QRS event in the ventricular and far‐field EGM channel).…”