EFFECTS OF PROPOFOL ON THE FUNCTION OF NORMAL, COLLATERAL-DEPENDENT, AND ISCHEMIC MYOCARDIUM

To examine the effects of propofol on the function of normal, collater al-dependent, and acutely ischemic myocardium, nine mongrel dogs were chronically instrumented with hydraulic occluders and ameroid constric tors were inserted around the left coronary artery, pressure transduce rs in the left ventricle, and heparin-filled catheters in the descendi ng aorta and the left atrium. Regional function of normal, collateral- dependent, and acutely ischemic myocardium was assessed by sonomicrome try. Propofol (5 mg/kg intravenously) reduced function in normal myoca rdium (-15% +/- 5%, 1 min and -14% +/- 5%, 3 min after injection) and in collateral-dependent myocardium (-14% +/- 5% and -13% +/- 5%) to si milar degrees, whereas ischemic myocardial function deteriorated signi ficantly more (-25% +/- 10% and -23% +/- 10%, P < 0.01). Although left ventricular end-diastolic pressure remained unchanged and left ventri cular contractility was reduced (-16% +/- 4%, 1 min and -15% +/- 3%, 3 min after propofol, P < 0.01), significant increases in heart rate (3 5% +/- 7% and 26% +/- 7%, P < 0.01) and decreases in coronary perfusio n pressure (-14% +/- 5%, P < 0.05 and -19% +/- 6%, P < 0.01) occurred, likely affecting the function of ischemic myocardium. Thus, whereas c ollateral-dependent myocardium tolerated these adverse hemodynamic eff ects, ischemic myocardium responded with impairment of regional functi on that was significantly more pronounced than the impairment which oc curred in normal or collateral-dependent areas after a 5 mg/kg intrave nous bolus of propofol.