A Comparison of the Effects of Isoflurane and Desflurane on Myocardial Contractility in Isolated Sprague-Dawley Hearts

Lee, Mi Gyeong; Jeong, Woo Young; Lim, Sang Ho

Abstract

BACKGROUND: Desflurane has some cardiovascular effects similar to isofl-urane. Desflurane has decreased systemic vascular resistance and demonstrated a myocardial depressant property in vivo animal stulies. The purpose of this study was to compare the myocardial and coronary effects of desflurane and isoflurane.
METHODS
Cardiac effects were examinated in 24 rat hearts perfused with modified Krebs solution containing 1 MAC and 2 MAC desflurane or isoflurane for 10 min. at each concentration in a retrograde manner. Left ventricle pressure, heart rate and rate of change of ventricular pressure (dp/dt) were mea-sured, as were coronary flow and partial oxygen pressure. Oxygen delivery, myocardial oxygen consumption and percent oxygen extraction were calculated by each measurement.
RESULTS
Heart rate, left ventricle pressure and dp/dt decreased each anesthetic similarly in a concentration-dependent manner. Heart rate decreased by 243.86 15.7 beats/min at 1 MAC and 219.14 15.8 beats/min at 2 MAC with isoflurane (control: 262.99 2.35 beats/min.) and by 250 23 beats/min at 1 MAC and 223.89 23 beats/min at 2MAC with desflurane (control 266.94 22.30 beats/min). Coronary flow increased by 13.72 0.99 ml/g/min at 1 MAC and 14.30 1.05 ml/g/min at 2 MAC with isoflurane (control :12.04 0.84 ml/g/min) and by 12.80 1.63 ml/g/min at 1 MAC and 13.71 1.46 ml/g/min at 2 MAC with desflurane (control 14.04 1.22 ml/g/min). Oxygen delivery increased proportionally with coronary flow. The increase in MVO2 was accompanied by a decrease in heart rate and pressure but there were no significant differences. Percent oxygen extraction decreased in a concentration dependent manner.
CONCLUSIONS
This study shows that desflurane and isoflurane decreased heart rate, myocardial depression and coronary vasodilating effects, resulting in improved oxygen perfusion effects.