Contractility in Humans after Coronary Artery Surgery: Echocardiographic Assessment with Preload-adjusted Maximal Power

Background: Propofol's unique pharmacokinetic profile offers advantages for titration and rapid emergence in patients after coronary artery bypass graft (CABG) surgery, but concern for negative inotropic properties potentially limits its use in these patients. The current study analyzed the effect of various propofol plasma concentrations on left ventricular (LV) contractility by means of a single-beat contractile index based on LV maximal power (PWRmax).

Methods: The study was conducted in 30 patients after CABG surgery. Immediately after admission to the intensive care unit (ICU), four different plasma concentrations of propofol, 0.65, 1.30, 1.95, and 2.60 [micro sign]g/ml, were established. At each concentration level, the cardiac and vascular effects of propofol were studied by combining echocardiographic data with invasively derived aortic root pressure. Preload was characterized by LV end-diastolic dimensions. Afterload was indicated in terms of indexed systemic vascular resistance (SVRI), LV end-systolic meridional wall stress (LV-ESWS), and arterial elastance (Ea). Quantification of effects on contractility was achieved by preload-adjusted PWRmax.

Results: Myocardial contractility did not change during a fourfold increase in propofol plasma concentration. Preload-adjusted PWRmax amounted to 3.90 +/- 1.75 W [middle dot] ml-2 [middle dot] 104, 3.98 +/- 1.69, 3.94 +/- 1.70, and 3.88 +/- 1.72, respectively (mean +/- SD). With respect to ventricular loading conditions, propofol caused a significant reduction in both pre- and afterload.