Ventricular relaxation and mitral opening time in various ventricular conditions of old age.

This phonocardiographic-echocardiographic study was based on measurement of the interval between the aortic component of the second sound (IIA) and the peak of the E wave of the mitral echogram. The study was performed in 20 cases of left bundle branch block (LBBB), 10 cases of right bundle branch block (RBBB), 10 cases of old myocardial infarct (MI), and 10 cases of systemic hypertension (HY). All patients were above 60 years of age, and their data were compared with those of old persons without evidence of heart disease serving as controls. The IIA-E interval was found markedly prolonged in LBBB, less prolonged in MI and RBBB, and was shortened in HY. A dynamic analysis revealed that this interval results from the isovolumic relaxation period (IRP) of the left ventricle plus the "opening time" of the mitral valve. The changes observed were explained as resulting from a modification of the IRP that should be correlated with a similar modification of the isovolumic contraction time. Myocardial fibrosis would cause prolongation of IRP through structural lesions while hypertension would cause abbreviation of IRP through hormonal effects modifying both contraction and relaxation.