Abstract
Even though the left bundle branch block (LBBB) morphology in the surface electrocardiogram (ECG) is expected after right ventricular endocardial pacing, the right bundle branch block (RBBB) morphology may be paradoxically seen in around 8 to 10% of patients. The paced RBBB morphology should be given special attention in terms of safe RV pacing or septal and free wall perforation. Simple techniques such as moving the leads V1-2 to one interspace lower than standard (Klein maneuver) and combining frontal QRS axis between -30° to -90°, precordial transition point at or within V3, and absence of S wave in lead I as an algorithmic approach may correctly identify the pacemaker lead in right ventricle with high sensitivity, specificity, and positive predictive value.
Highlights
The Left Bundle Branch Block (LBBB) pattern in the surface electrocardiogram (ECG) is the usual expected morphology after transvenous right ventricular (RV) pacing with pacemaker capture
What is of interest is that a paced left bundle branch block (LBBB) morphology can be appreciated with left ventricular (LV) pacing when the pacing is from the middle and the great cardiac veins.[17]
A study conducted by Klein et al.[19] reported eight patients with right bundle branch block (RBBB) pattern in leads V1-2, LBBB pattern in lead I, and pacing lead located in the RV apex
Summary
The Left Bundle Branch Block (LBBB) pattern in the surface electrocardiogram (ECG) is the usual expected morphology after transvenous right ventricular (RV) pacing with pacemaker capture. The Normal QRS Patterns During Right Ventricle Pacing Regardless of the site in RV, RV pacing produces LBBB morphology in the precordial leads defined as the absence of a positive complex in lead V1 recorded in the fourth or fifth intercostal space.[8] During RV apical pacing, the depolarization begins in the inferior part of the heart and travels superiorly away from the inferior leads. The apical LV pacing produces negative QRS complexes in leads V4 to V6 while the basal LV pacing (Figure 4) produces positive QRS complexes in the same leads.[16] What is of interest is that a paced LBBB morphology can be appreciated with LV pacing when the pacing is from the middle and the great cardiac veins.[17] The paced frontal plane often shows a right axis deviation.[9]. 3rd intercostal spaces) or development of ventricular fusion beat too produces RBBB morphology
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