The Annals of Thoracic Surgery, Vol 41, 622-629, Copyright © 1986 by The Society of Thoracic Surgeons
The electrophysiological effects of calcium channel blockade during standard hyperkalemic hypothermic cardioplegic arrest
TB Ferguson Jr, RJ Damiano, PK Smith, WC Buhrman and JL Cox
The addition of calcium channel-blocking agents to a standard hyperkalemic
hypothermic cardioplegic solution has been examined both experimentally and
clinically. None of these studies, however, have investigated the effect of
calcium blockade during cardioplegic arrest on the specialized cardiac
conduction tissues and on the subsequent development of arrhythmias after
arrest. The present study examined the effect of adding nifedipine to
standard cardioplegic solution administered in a canine experimental
preparation modeled on routine clinical techniques. The time to and
duration of electrical arrest following the administration of cardioplegia
and the functional electrophysiological variables before and after arrest
were measured using a 32-channel data acquisition system. The addition of
nifedipine shortened the time to electrical arrest and prolonged the
duration of arrest compared with standard potassium cardioplegic solution
alone, without a deleterious effect on conduction function immediately
after arrest. The occurrence of low-amplitude electrical activity (LEA) in
both atria and ventricles during arrest was significantly reduced by the
addition of nifedipine, thereby suggesting a possible correlation between
LEA and calcium-mediated conduction occurring under conditions of standard
cardioplegic arrest.
