The Annals of Thoracic Surgery, Vol 43, 534-538, Copyright © 1987 by The Society of Thoracic Surgeons
Prevention of myocardial electrical activity during ischemic arrest with verapamil cardioplegia
RW Landymore, AE Marble, A Trillo, G Faulkner, MA MacAulay and C Cameron
The effect of potassium cardioplegia and potassium cardioplegia containing
verapamil hydrochloride on myocardial preservation and electrical activity
during prolonged aortic occlusion was examined in 40 adult mongrel dogs.
Twenty-four animals (Group 1) received potassium cardioplegia, and 16
animals (Group 2) received potassium verapamil cardioplegia. Potassium or
potassium verapamil cardioplegia, 10 ml per kilogram of body weight, was
administered after application of the aortic cross-clamp and at 30-minute
intervals during the 90-minute arrest. Myocardial temperature was
maintained within a range of 8 degrees to 10 degrees C with topical ice
saline solution, and electrical activity was monitored with specially
designed plunge electrodes. Plunge electrode activity was recorded from the
myocardium during arrest in 16 of the 24 animals in Group 1; no electrical
activity was present in the animals in Group 2 (p less than .001). The
addition of verapamil to potassium cardioplegia increased the tolerance of
the myocardium to prolonged ischemia and resulted in less depletion of
high-energy phosphate stores and better preservation of mitochondrial
ultrastructure and left ventricular function. These data suggest that
verapamil augments the preservation provided by potassium cardioplegia by
initiating and maintaining a more complete electrical arrest.
