Comparison of cardiac electrophysiologic variables in blood perfused and buffer perfused isolated working rabbit hearts. Gillis, Anne M., Elzbieta Kulisz, and Heather J. Mathison. The Cardiovascular Research Group, The University of Calgary, Calgary, Alberta, Canada
APStracts 3:0068H, 1996.
The effects of crystalloid buffer and blood-buffer perfusates on cardiac electrophysiologic parameters were compared in four groups of isolated working rabbit hearts. Hearts were perfused with Krebs -Henseleit buffer or a combination of blood and Krebs-Henseleit buffer (10% hematocrit) over a range of left ventricular afterload (30 cm H2O - 100 cm H2O) and a range of cardiac outputs (30 ml/min - 180 ml/min). Left ventricular monophasic action potential duration (APD) was significantly shorter at low afterload and high cardiac output in the buffer perfused hearts (114 +/- 35 msec) compared to the blood perfused hearts (177 +/- 23 msec, p &LT 0.001). APD shortened in blood perfused hearts following an increase in afterload to 100 cm H2O (p &LT 0.05) and APD was similar in the blood perfused hearts (151 +/- 19 msec) compared to the buffer perfused hearts (142 +/- 24 msec, p = NS). The ventricular effective refractory period (VERP) was significantly shorter at low afterload in the buffer perfused hearts (154 +/- 32 msec) compared to the blood perfused hearts (227 +/- 17 msec, p &LT 0.001). VERP shortened in the blood perfused hearts following an increase in afterload to 100 cm H2O (p &LT 0.05) and VERP was similar in the blood perfused hearts (166 +/- 26 msec) compared to the buffer perfused hearts (151 +/- 37 msec, p = NS). Determination of VERP was associated with induction of ventricular fibrillation in 10 of 15 buffer perfused hearts whereas ventricular fibrillation was not observed in the blood perfused hearts (p &LT 0.001). Thus, significant differences in ventricular repolarization and cardiac hemodynamics are observed in working rabbit hearts perfused with a blood-buffer perfusate compared to hearts perfused with a crystalloid buffer. Blood perfused working hearts are electrophysiologically more stable. 

Received 29 March 1995; accepted in final form 19 January 1996.
APS Manuscript Number H307-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96