A case of narrow complex bigeminy, what is the underlying rhythm?

Narrow complex bigeminy is a common electrocardraphic finding that can be caused by second degree sinoatrial exit block or ectopic atrial bigeminy. These rhythms can be very challenging to distinguish on a 12-lead electrocardiogram. In this case of an elderly woman who presented with narrow complex bigeminy, we review the differentiating features of second degree sinoatrial exit block and ectopic atrial bigeminy.
Source: Journal of Electrocardiology - Category: Cardiology Authors: Source Type: research