[Assessment of left ventricular contractility (Emax) and arterial load (Ea) in humans by transesophageal echocardiography and radial artery pressure tracing].

We determined both the slope of the left ventricular end-systolic pressure-volume relation (Emax), which is a measure of contractility independent of loading conditions, and the slope of the arterial end-systolic pressure-stroke volume relation (Ea), which is a measure of arterial load independent of ventricular function, in 10 patients undergoing elective noncardiac surgery. Left ventricular end-systolic volume (Ves) was measured by transesophageal echocardiography and instantaneous left ventricular end-systolic pressure (Pes) was estimated from the dicrotic notch pressure in the radial artery. Emax was calculated during afterload reduction (nicardipine 30 micrograms.kg-1 iv), and the correlation of Emax to either Pes/Ves ratio or MAP (mean arterial blood pressure)/Ves ratio was accomplished in order to investigate whether these indices were clinically useful measurements of ventricular function or not. Ea was also calculated from the data obtained before and 2-3 min after nicardipine iv. The averaged Emax and x-axis intercept (Vo) were 3.11 mmHg.ml-1 and -3.8 ml, respectively. The correlation coefficient obtained between Emax and Pes/Ves was 0.96, and that obtained between Emax and MAP/Ves was 0.97. Ea decreased significantly (P < 0.05) following intravenous nicardipine, demonstrating a decreased arterial load. The direction of changes in Ea was similar to that reported previously in systemic vascular resistance. From these results, we conclude that measurement of Emax (or Pes/Ves, MAP/Ves) and Ea using transesophageal echocardiography and radial artery pressure tracing is feasible and these are a useful tool to estimate left ventricular performance and arterial load during surgery.