Left Ventricular Function in Conscious Man and during Halothane Anesthesia

Abstract

The effect of halothane on left ventricular (LV) function in healthy, nonmedicated patients before operation was studied. Using local anesthesia, with the aid of fluoroscopy, catheters were placed in the left ventricle, thoracic aorta and pulmonary artery. Thermodilution cardiac output derivatives and left ventricular pressure indices were measured awake and during anesthesia with halothane, 0.9 and 1.8% (end-tidal). Ventilation was controlled to maintain PaCO2 and pHa at the awake values. Dose-dependent decreases in cardiac index (3.98 .fwdarw. 3.48 .fwdarw. 2.86 l/min .cntdot. m2), stroke volume index (50.1 .fwdarw. 44.6 .fwdarw. 38.5 ml/m2), LV dP/dtmax (1440 .fwdarw. 1200 .fwdarw. 1000 mm Hg/sec), dP/dtmax/IP (20.7 .fwdarw. 17.0 .fwdarw. 15.0 sec-1), cardiac work (11.76 .fwdarw. 8.15 .fwdarw. 5.52 .times. 102 mm Hg/ml/min .cntdot. kg) and mean aortic pressure (MAP) (94 .fwdarw. 80 .fwdarw. 69 mm Hg) were accompanied by increased left ventricular end-diastolic pressure (LVEDP) (11 .fwdarw. 12 .fwdarw. 14mm Hg), without change in heart rate or systemic vascular resistance (SVR). Preload and afterload (MAP and SVR) changes could not account for the demonstrated depression in ventricular function. Thus, in man, as in the dog, halothane has a direct depressant effect on LV function.