Late, but Before Schedule-A Bigeminal Rhythm with Blocked Premature Junctional Beats

Premature supraventricular ectopic beats are common findings in ambulatory ECG monitoring. Blocked ectopic beats may occur if the premature beat coincides with the refractory period of the downstream conductive tissues. We report of an uncommon, symptomatic bigeminal rhythm which resulted in an abrupt decrease of the heart rate because of blocked P waves. The blocked P waves appeared uncommonly late in the cardiac cycle because of a very His-near activation site. For anatomic reasons treatment was difficult and the patient received a pacemaker.