The linearity of the end-systolic pressure-volume relationship in man and its sensitivity for assessment of left ventricular function.

Abstract

The linearity and sensitivity of the end-systolic pressure-volume (P-Ves) relation to the inotropic state of the left ventricle were investigated in 11 patients with coronary heart disease and one patient with congestive cardiomyopathy. To minimize autonomic reflex responses, propranolol, 0.15 mg/kg, and atropine, 1 mg, were administered i.v. at the beginning of the study. Three ventriculograms were performed: at rest, after oral isosorbide dinitrate, 10 mg (systolic pressure decrease greater than or equal to 15 mm Hg), and during infusion of methoxamine, 2 mg/min (systolic pressure increase greater than or equal to 10 mm Hg). The three points of the Pv-Ves relation showed linearity (r greater than or equal to 0.96). The relation between the slope k of the P-Ves relation and the left ventricular ejection fraction at rest was best described by an exponential function (r = 0.94). The use of peak systolic pressure instead of end-systolic pressure showed equally good results. The intercept of the P-Ves line on the abscissa, which represents the theoretical end-systolic volume at zero pressure, was not related to the ejection fraction under control conditions. The P-Ves relation in postextrasystolic beats was displaced toward the left (smaller end-systolic volumes) and became steeper.