[The end-diastolic pressure-volume relationship of the left ventricle. Significance for the indices of compliance and diastolic rigidity of the ventricle].

In order to evaluate the importance of the indices of ventricular rigidity and compliance (k=dP/dV.P and dV/dP), three groups of patients were studied and compared. A simplified method of calculating the diastolic compliance made use of the values of end-diastolic volume (EDV) measured by cineangiography, and of end-diastolic pressure (EDP), using the assumption that the relationship P-V is an exponential one arising from the ordinate: 0.43 mmHg. The correlation between EDP and EDV, which was positive in 19 coronary artery patients, was in fact negative in 11 patients with obstructive cardiomyopathy (OCM), and insignificant in 12 control patients. There were multiple correlations between k, EDPs and EDVs in 11 OCMs, and none in the two other groups. The ratio dV/dP decreased in end-diastole both in the OCM group and in the coronary group, and did not reflect the difference in pathology between these two groups. On the other hand k was increased in the patients with OCM, normal in the coronary patients, and represented in the former a primary modification in the relationship P-V and a primary increase in diastolic rigidity.