Contractile state of the left ventricle in man as evaluated from end-systolic pressure-volume relations

Abstract

End-systolic pressure [P(ES)], volume [V(ES)], wall tension [T(ES)] and circumference [C(ES)] of the human left ventricle were studied at cardiac catheterization in 24 subjects with varying degrees of left ventricular dysfunction. Acute alterations in systolic load consistently resulted in changes in V(ES) and C(ES), with a smaller volume and circumference characterizing the lower systolic load in each subject. End systolic pressure-volume lines were constructed by plotting P(ES) against V(ES) at the higher and lower systolic load in each subject. The slope of the resultant lines was considerably steeper for normal than for poorly contractile left ventricles. V(O), the volume axis intercept of the line (i.e., the theoretical V(ES) at P(ES) = 0) was signiicantly smaller for normal than for poorly contractile ventricles. Similar findings were noted for C(O), the theoretic end-systolic circumference at zero end-systolic ventricular wall tension. Postextrasystolic potentiation resulted in decreased V(ES) and C(ES) with no change in P(ES) and only a slight fall in T(ES). In conclusion, end-systolic pressure-volume and tension-circumference relations reflect the contractile state of left ventricular myocardium. Quantitation of these relationships may provide a useful new approach to the assessment of myocardial function in man.