Sameness in the Same Lead

Report:

Atrial fibrillation

VEB (6th complex)

Intraventricular conduction delay (unspecified)

Comment:

In all fairness, most of us would disregard the 6th beat if all there was to see was the rhythm strip and the strip was obtained during routine monitoring. Here, however, the reader is on the lookout for the reason the trace is in the Library in the first place and would notice the 6th complex as slightly different, suggesting, perhaps, a ventricular fusion between a VEB and a conducted supraventricular beat. Or, even, a supraventricular AF beat with slightly different conduction – there is no attempt at a compensatory pause, usually present in AF after VEBs.

With the full 12-lead ECG (Fig 182a), the same beat is recorded in leads aVR, aVL and 3 simultaneously. Now it looks completely different from the flanking beats – obviously a VEB. There is no need to adduce any fusion, although in AF – without the P wave “markers” – this cannot be completely excluded. As Marriott puts it, you cannot establish sameness from a single lead132.

The 12-lead ECG shows the IVCD to be a 0.20” broad LBBB. Lead 2 is not well suited for defining broad complexes, be they bundle branch blocks or ectopic ventricular beats. This is another lesson from Marriott133.

The width of the LBBB, barring some unknown metabolic or pharmacological influence, reflects advanced myocardial disease. The interesting feature is a relatively tall R wave in lead V2, with decreasing R amplitude in V3 and V4. This suggests old anterior infarction, but the patient in fact had normal coronary arteries demonstrated as part of his transplant workup; there were no segmental wall motion abnormalities either. I have seen this pattern in several patients with primary congestive cardiomyopathy.