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. Author manuscript; available in PMC: 2010 May 27.
Published in final edited form as: Heart Rhythm. 2009 Jun 21;6(10):1514–1521. doi: 10.1016/j.hrthm.2009.06.025

Figure 1.

Figure 1

Electrocardiograms (ECGs) from a 65-year-old woman with a history of recurrent syncopal episodes showed normal sinus rhythm, complete left BBB pattern, and periods of Mobitz type II AV block. A: Electrophysiological study (EPS) showed intra-His bundle block with split His bundle potential (h1, h2) and a 5-ms increment of the h1, h2 interval before block. Intra-His bundle block was initially unrecognized because the h1 deflection was overlooked. B: Rhythm strip 1 day later shows atrial tachycardia (rate 150–170 bpm) leading to TD-PAVB with 5.6-second ventricular asystole. AV conduction improved when the tachycardia slowed down (probably with a period of 2:1 AV block). Note the different time scale of the EPS recording.