The Effects of Diltiazem with Desflurane on Coronary Blood Flow and Contractility in Isolated Rat Heart

Nam, Sang Sun; Lim, Sang Ho; Lee, Mi Kyoung

Abstract

BACKGROUND: Calcium channel blockers and volatile anesthetics have depressant effects on cardiac function. Both groups of drugs appear to exert both qualitatively and quantitatively different effects on electrophys-iologic and mechanical function. The authors examined the direct in-vitro effects of diltiazem in the presence of a desflurane using an isolated rat heart.
METHODS
Isolated Sprague-Dawley rat hearts (N = 40) were perfused at a constant pressure with an oxygenated modified Krebs' solution. After the stabilization period, they were subdivided into two groups. The groups were subjected to different concentrations of desflurane (6, 12, 18 vol%) alone or 100 ng/ml diltiazem with the same concentrations of desflurane, respectively. Isovolumetric left ventric ular pressure (LVP), heart rate and rate of change of ventricular pressure (dp/dt) were measured via a thin, saline-filled latex balloon and transducer. Coronary flow and oxygen tension were measured at the coronary inflow and outflow sites. Oxygen delivery, myocardial oxygen consumption and percent oxygen extraction were calculated with each measurement.
RESULTS
The combination of diltiazem and desflurane (6, 12 and 18 vol%) dose-dependently depressed LVP and dp/dt more than desflurane alone. Coronary flow and oxygen delivery increased in a dose- dependent fashion, but there was no statistical difference between the groups. The decreases of heart rate, myocardial oxygen consumption and percentage of oxygen extraction were dependent on the concentration of desflurane. Arrhythmias occurred only with a high desflurane (18 vol%) concentration and the high desflurane concentration plus diltiazem.
CONCLUSIONS
These results demonstrate that the myocardial depressant effect of diltiazem plus desflurane is greater than desflurane alone. The authors suggest that administration of diltiazem during high concentrations of desflurane anesthesia could result in deleterious cardiac depression and arrhythmias.