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Images and Case Reports in Arrhythmia and Electrophysiology

Paroxysmal Atrioventricular Block Induced by a Single Ventricular Premature Beat in the Absence of Overt Atrioventricular Conduction System Disease

Manish Undavia, MD and Avi Fischer, MD

From the Section of Electrophysiology, Mount Sinai Medical Center, New York, NY.

Correspondence to Avi Fischer, MD, Electrophysiology Section, Cardiovascular Institute, Mount Sinai Medical Center, One Gustave L. Levy Place, Box 1054, New York, NY 10029. E-mail avi.fischer@mssm.edu

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Paroxysmal atrioventricular (AV) block is an unusual phenomenon that has been previously described. We report the case of a 78-year-old man who presented after an episode of syncope while seated in church. On presentation to the hospital, the initial electrocardiogram showed sinus rhythm with a normal PR interval, QRS duration, and corrected QT interval. During telemetry monitoring, several episodes of high-grade AV block were observed, and all episodes occurred after a single premature ventricular complex (Figure). AV conduction resumed after several nonconducted P waves (Figure). Ultimately, the patient was implanted with a dual-chamber pacemaker.

View larger version (107K):   Figure. AV block after a premature ventricular complex. The sinus rate is unchanged before and after the AV block. Resumption of AV conduction occurs with a narrower QRS and with delayed conduction.

 
Advanced AV block has been known to occur after a single ventricular premature complex in patients with advanced His-Purkinje system disease. Transient AV conduction abnormalities, as a result of rapid ventricular pacing, is thought to occur as a result of depressed amplitude and excitability of Purkinje fibers and may require retrograde conduction to the Purkinje system.¹ Perpetuation of the AV conduction disturbance may result from phase 4 block; however, this phenomenon generally occurs in the presence of preexistent intraventricular and AV conduction disturbances such as bundle-branch block and Mobitz II block.² It has also been described in the absence of overt AV conduction disease. The precise mechanism for the occurrence of paroxysmal AV block remains speculative but is thought to . . . [Full Text of this Article]