This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by ARAVINDAKSHAN, V. Articles by DAOUD, F. S. Search for Related Content PubMed PubMed Citation Articles by ARAVINDAKSHAN, V. Articles by DAOUD, F. S.

(Circulation. 1974;50:255.)
© 1974 American Heart Association, Inc.

---

Depression of Escape Pacemakers Associated with Rapid Supraventricular Rate in Patients with Atrioventricular Block

V. ARAVINDAKSHAN M.D.¹; BORYS SURAWICZ M.D.¹; FUHEID S. DAOUD M.D.¹

¹ From the Department of Medicine, Division of Cardiology, University of Kentucky College of Medicine, Lexington, Kentucky, and Veterans Administration Hospital, Lexington, Kentucky.

Intermittent failure of escape pacemakers to maintain an effective rate when the supraventricular rate was rapid was observed in three patients with complete, or high degree atrioventricular block. In two of these patients asystole or slowing of escape pacemaker rate to less than 20 per minute was reproduced by atrial pacing at rates from 125 to 150 per minute. We localized the site of the block and the site of escape pacemaker proximal to the bifurcation of the His bundle in all patients. We assume that a critical increase in atrial rate facilitates penetration of the nonconducted supraventricular impulses into the area of block causing discharge of the escape pacemaker. We suggest that such concealed discharge of escape pacemakers should be considered as a cause of slow and variable rate of escape pacemakers in patients with block proximal to the bifurcation of the His bundle.

Key Words: Concealed conduction • Asystole • Concealed discharge • Syncope • His bundle electrograms • Atrial pacing

Submitted on March 5, 1974
Accepted on April 8, 1974