Electrocardiographic Patterns during:

Abstract

Pacing within the GCV resulted in a left bundle branch block (LBBB) morphology with no or minimal R-wave in V(1) in 14 patients and a right bundle branch block (RBBB) pattern (R > S in lead V(1)) in four patients. In one patient, lead V1 during GCV pacing was isoelectric (R = S). A more distal pacing site in the GCV yielded a LBBB pattern in all the patients. All leads placed in the MCV resulted in a LBBB configuration. An ECG pattern with a RBBB pattern was invariably recorded during LV pacing in 125 consecutive outpatients with biventricular pacemakers and LV leads in the posterolatral and lateral coronary veins. Knowledge of the ECG patterns from various pacing sites in the coronary venous system may be helpful for troubleshooting all types of pacing systems, especially those where the coronary venous pacing site is unintentional.

Universal Algorithm for Diagnosis of Biventricular Capture in Patients with Cardiac Resynchronization Therapy

“…A positive QRS in V1 and a negative QRS in V6 are observed in almost all patients with pure LV‐only pacing. However, a dominant R in V1 can be absent with extremely paraseptal and apical LV lead positions, which are generally avoided, and a lack of QS in V6 can be observed with very basal LV lead positions . Depolarization wave fronts starting in the posterior or lateral LV free wall are directed anteriorly and to the right (toward V1 and away from V6), with the opposite situation occurring in most cases of RV‐only pacing.…”

Electrocardiographic Diagnosis of Biventricular Pacing in Patients with Nonapical Right Ventricular Leads

“…By comparison, during LV‐only pacing, a QRS complex in lead V6 is negative in the vast majority of cases (a QS complex); only in a minority of cases with a very basal LV lead tip position is the QRS positive in lead V6, and even then, it often commences with a Q wave. Another, even less likely reason for a positive QRS in lead V6 during LV‐only pacing is LV lead placement in the distal anterior or posterior interventricular vein, which can result in a left bundle branch block‐type QRS pattern 9 …”

Site-Specific Differences in Latency Intervals during Biventricular Pacing: Impact on Paced QRS Morphology and Echo-Optimized V-V Interval

“…Several situations should be ruled out in the presence of a negative QRS complex in lead V 1 . These include incorrect placement of lead V 1 (too high on the chest), lack of LV capture, suboptimal LV lead position (including anterior or middle cardiac vein), LV lead displacement, ventricular fusion with the conducted QRS complex, and intraventricular conduction disorder that may or may not be associated with prolonged LV latency 1,5,17–20 . Two of three patients who maintained an LBBB pattern after AV and V‐V interval optimization demonstrated fusion with the spontaneously conducted QRS complex.…”