Electrocardiographic manifestations of concealed junctional ectopic impulses.

Abstract

SUMMARY Thirteen episodes of concealed junctional ectopic impulses (JEI) in ten patients are described. In nine patients the JEI manifested as isolated automatic impulses and in one as a parasystolic junctional tachycardia. In addition to the previously described unexpected prolongation of the P-R, Type I and Type II A-V block, the following phenomena were recorded: 1) marked, greater ATRIOVENTRICULAR (A-V) BLOCK due to concealed junctional ectopic impulses (JEI) was first described in 1947.' Not until 1962 was the next case of A-V block due to JEI reported.' To the best of our knowledge a total of 11 instances of spontaneous JEI concealed within the junctional tissue because of an antegrade and retrograde block have been reported.3 "' In each instance the presence of JEI was suspected by its effect on the behavior of the subsequent impulse. The assumption that the unexpected and "unphysiological" behavior of A-V conduction was due to concealed JEI proposed by Langendorf and Mehlman' was confirmed in man by direct recording from the His bundle by Rosen, Rahimtoola and Gunnar,5 in the dog by Damato, Lau and Bobb" and in the isolated rabbit A-V conduction system by Moore, Knoebel and Spear.12 The purpose of this communication is to present 13 episodes of concealed JEI recorded in ten patients. Manifestations, phenomena, not previously described include: 1) initiation of a marked, greater than 400 msec, than 400 msec, and persistent prolongation of the P-R interval, 2) striking changes in the duration of the P-R with an occasional sequence of R-P and P-R intervals simulating "supernormal" A-V conduction, 3) unexpected variation of the junctional escape interval explained by junctional parasystole with entrance block, 4) postponed conpensatory pause, 5) concealed junctional discharge with reciprocation.prolongation of the P-R interval; 2) persistence of this prolongation; 3) wide variation of P-R duration in the same record with occasional R-P, P-R relationship suggesting " supernormality" of A-V conduction; 4) variation of junctional escape interval; 5) postponed compensatory pause; and 6) reciprocation due to concealed junctional discharge, as opposed to the well recognized phenomenon of concealed reciprocation.

Evidence for the presence of electrotonic depression of pacemakers in the rabbit atrioventricular node. The effects of uncoupling from the surrounding myocardium

“…However, non-reentrant AV nodal tachycardias (presumably not caused by sympathetic stimulation) having a higher frequency than sinus rhythm are reported from several recent in vivo (9,15,(34)(35)(36) and in vitro studies (44). This indicates that junctional pacemaker fibers are, under certain conditions, capable of impulse formation at higher rates than sinus rhythm.…”

A confused ECG with multiple rhythms caused by atrial premature contractions

“…When APCs conducted to ventricle, the narrow QRS complex extrasystole as a compensatory rhythm disappeared and adjacent sinus impulses could conduct to ventricle. [ 3 ]…”

Mobitz Type II Second‐Degree Atrioventricular Block with Narrow QRS and Junctional Extrasystoles: What is the Mechanism?

“…However, they also may appear in sinus rhythm and manifest as nonconducted atrial bigeminal extrasystoles, premature ventricular depolarizations, double nodal pathway, or junctional tachycardia. Finally, they may manifest themselves by concealed conduction that leads to sudden changes in the PR interval or even to second‐degree AV block . This last form of presentation should always be considered a possibility with the sudden appearance of Mobitz Type II AV block in a patient with a narrow QRS complex.…”