[An apex cardiographic method of determining the moment of mitral valve opening and duration of its isovolumetric relaxation].

By analyzing the simultaneous recordings of M-type echocardiogram of the mitral valve, apexcardiogram (ACG) phonocardiogram (PCG) in 49 healthy persons, 30 patients with II stage hypertension and 39 patients with unstable angina pectoris was established that the opening of the mitral valve coincides with the moment in which the discending arm of the ACG deviates from its tangent (determined by two points--the first is the point of intersection of the ACG with the perpendicular raised from the initial highfrequency vibrations of the aortic component of the II tone: the second is 20 ms from the first on the discending arm of the ACG). The method allows the determination of the exact moment of the opening of the mitral valve and the duration of the isovolumetric relaxation and of the period of the active suction by the ACG and the PCG only. This increases the apexcardiographic potentialities in the functional diagnosis of the left ventricle.