AJP - Heart and Circulatory Physiology, Vol 257, Issue 5 1534-H1542, Copyright © 1989 by American Physiological Society
Effect of voltage and charge of electrical ablation pulses on canine myocardium
G. H. Bardy, P. L. Sawyer, G. W. Johnson, T. D. Ivey and D. D. Reichenbach
Department of Medicine, University of Washington, Seattle 98195.
Multiple paired lesions produced by a train of high-voltage low-charge
rectangular pulses (20 A, 30 microsecond) and a train of low-voltage
high-charge rectangular pulses (2 A, 300 microsecond) were made to the left
ventricular epicardium of 23 dogs to determine the relative influence of
voltage and charge delivery on injury of canine myocardium. Both pulsing
methods contained equal amounts of energy (15 J) delivered over equal
periods of time (100 ms), and both pulsing methods were nonarcing and
therefore nonbarotraumatic. The volume of cardiac tissue injury resulting
from both types of pulses was then evaluated from planimetered serial
histological sections after 1, 10, and 30 days. Over the 30-day period,
lesion size progressively decreased to 56% of its original value for the
high-voltage low-charge pulse. In contrast, lesion size from the
low-voltage high-charge pulse remained relatively constant, decreasing only
12% of its original value. These results indicate that when energy delivery
is held constant, voltage, not charge, is the dominant mediator of cell
injury. Also, cells subjected to high voltages appear to recover partially
over time with significantly less constancy of tissue injury than that seen
with low-voltage high-charge pulses.
