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(Circulation. 1974;50:389.)
© 1974 American Heart Association, Inc.

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Demand Pacemaker Malfunction Due to Abnormal Sensing

Report of Two Cases

MENASHE B. WAXMAN M.D.¹; NEIL D. BERMAN M.D.¹; GINES SANZ M.D.¹; EUGENE DOWNAR M.B.¹; PAUL MENDLER ¹; KENNETH W. G. TAYLOR PH.D.¹

¹ From the Division of Cardiology and the Department of Biomedical Engineering, Toronto General Hospital, and the Department of Medicine, University of Toronto, Ontario, Canada.

Two cases with external demand pacemakers are presented because of abnormal prolongation in the pacing interval. In both cases, pacemaker inhibition was caused by signals which were not recorded by the conventional surface electrocardiograms. In one case, inhibition was related to a partial lead fracture which generated a voltage transient in the region of the T wave. In the other case, inhibition was caused by current emitted from a faulty pacemaker unit. In both cases precise localization of the problem was possible by simple bedside recordings and measurements.

Key Words: Pacemaker failure • Lead fracture • Biphasic stimulation

Submitted on March 6, 1974
Accepted on April 8, 1974