Linearity, load dependence, hysteresis, and clinical associations of systolic and diastolic indices of left ventricular function in man. Multicenter Study of Perioperative Ischemia (McSPI) Research Group.

Abstract

Measures of left ventricular (LV) contractility must be linear, load-independent, free of hysteresis, and sensitive to changes in inotropic state. These properties of measures of LV contractility have been assessed previously in animals, but never in man. Using a micromanometer and volume conductance catheter technology, we measured LV pressure and volume in 67 patients scheduled for CABG surgery. Measurements of the maximum rate of change of pressure relative to time versus end-diastolic volume (dP/dtMax-EDV), preload recruitable stroke work (PLRSW) and the end-systolic pressure-volume relationship (ESPVR), and measurements of the maximum negative rate of change of pressure relative to time versus end-diastolic volume (-dP/dtMax-EDV) and the end-diastolic pressure-volume relationship (EDPVR) were obtained in 62 patients. Comparisons of these measures of contractility during preload reduction and augmentation were performed in 48 patients using paired and unpaired student's t-tests. Index linearity was determined using linear regression analysis. Neither the slope nor the intercept of any of the three measures of contractility changed significantly with loading conditions. Heart rate demonstrated no physiologically significant baroreceptor-mediated changes during the perturbations. Comparing measures of LV function--ejection fraction (EF%), LV end-diastolic pressure (LVEDP), dP/dtMax-EDV, PLRSW, ESPVR, -dP/dtMax-EDV, and end-diastolic pressure-volume relationship (EDPVR)--in patients with a preoperative medical history of congestive heart failure (CHF), myocardial infarction (MI), and hypertension (HTN) demonstrated lower EF percent (62.4 +/- 16.7 vs 42.8 +/- 5.0 [p < 0.0002]) and lower ESPVR (2.27 +/- 1.98 vs 1.30 +/- 0.83 [p < 0.03]) in patients with a history of CHF.(ABSTRACT TRUNCATED AT 250 WORDS)