Manifest and concealed AV nodal reentry in Wenckebach type of AV conduction with AV junctional escape rhythm.

An electrocardiogram was obtained that was characterized by sinus rhythm with progressive prolongation of the PR interval not followed by a blocked sinus impulse. After a critically long PR interval, the QRS complex was followed by a premature P' wave, representing an echo beat, a manifest reentry in the atrioventricular (AV) node. The pause, occasioned by the premature P' wave, was at times interrupted by an AV junctional escape beat, occurring with an escape interval of 1.

[Pseudo AV dissociation caused by interpolated junctional extrasystoles in the presence of a first-degree AV block].

This presentation reports an electrocardiogram showing first degree A-V block with a very prolonged P-R interval of 0.80 sec. On several occasions an arrhythmia occurred, characterized by what looked like an A-V junctional escape rhythm with A-V dissociation.

Irregular ventricular tachycardia: a possible manifestation of longitudinal dissociation within the reentry pathway.

Sustained monomorphic ventricular tachycardia is usually regular; that is, it is associated with constant R-R intervals. In several cases, however, the cycles of ventricular tachycardia are more or less variable. Fifty-four cases of sustained monomorphic ventricular tachycardia were evaluated in order to assess whether tachycardia was regular.

Failure of parasystolic impulses to appear on schedule. Exit block due to concealed conduction of sinus impulses.

A 45-year-old patient free of any heart disease was admitted to the hospital with an electrocardiographic pattern of ventricular parasystole. The parasystolic rhythm was relatively fast, such that several consecutive ectopic complexes manifested. A later tracing reflected only isolated parasystolic complexes with long and fixed coupling intervals.

Supernormal conduction in the left bundle branch unmasked by the linking phenomenon.

This presentation reflects a case of phase-3 left bundle branch block (LBBB). Analysis reveals that relatively early QRS complexes are wide, whereas beats occurring later than a critical time are narrow. There are, however, two unexpected phenomena: (1) an overlap occurs between the range of R-R intervals resulting in normal intraventricular conduction and the range of R-R intervals resulting in LBBB pattern.