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

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.

Effects of Diltiazem with Sevoflurane on Coronary Flow and Myocardial Contractility in the Isolated Rat Heart / 대한마취과학회지

BACKGROUND: Calcium channel blockers and volatile anesthetics have depressant effects on myocardial contractility by limiting Ca2+ entry and altering intracellular Ca2+ release. The aim of this study was to compare the direct cardiac effects of isoflurane, desflurane and new volatile anesthetics, sevoflurane, in combination with diltiazem on the isolated rat heart. METHODS: Sprague-Dawley rat hearts (N = 60) were isolated and perfused with oxygenated modified Krebs solution at 55 mmHg with 0.5, 1, 2 MAC of isoflurane, desflurane or sevoflurane in combination with diltiazem 42 ng/ml (group 1) and 84 ng/ml (group 2). Isovolumetric left ventricular pressure (LVP), rate of change ventricular pressure (dP/dt), heart rate and coronary flow were measured. To examine the indirect metabolic effect due to autoregulation of coronary flow, O2 delivery (DO2), myocardial O2 consumption (MVO2) and percent O2 extraction (POE) were also monitored. RESULTS: Diltiazem plus volatile anesthetics depressed LVP and dP/dt and increased coronary flow dose-dependently. They also decreased heart rate. In the group 2, at 2 MAC of inhaled anesthetics heart rate was significantly decreased than group 1. There were no statistical significance between isoflurane, desflurane and sevoflurane on myocardial contractility and myocardial oxygenation. CONCLUSIONS: These in vitro RESULTS demonstrate that clinical dose of diltiazem plus isoflurane, desflurane or sevoflurane has similar effects on myocardial contractility and coronary flow.