[Genesis of protodiastolic extra heart sound in mitral stenosis: a phono-, apex-, echo- and cineangiographic study]

To clarify the genesis of a protodiastolic extra heart sound (S3') which was occasionally recorded at about the beginning of a diastolic rumble in mitral stenosis (MS), phono-, apex- and echocardiography were performed for 33 patients with MS, and left ventricular (LV) cineangiography was performed for eight of them. The patients were classified as S3'(+) and S3'(-) groups, according to whether they had S3'. Results were as follows: The S3' was synchronous with the rapid filling (RF) wave of the apexcardiogram (ACG). Its amplitude was proportional to the size of the RF wave. The RF wave was significantly sharper in the S3'(+) group as compared with that of the S3'(-) group. The S3' always appeared after onset of dispersion of dots in the velocity pattern of blood flow at the mitral valve orifice according to pulsed Doppler echocardiography. There was no significant difference between the S3'(+) and S3'(-) groups in the region of the mitral valve orifice according to two-dimensional echocardiography, and at the peak rate of change of the LV dimension during diastole as determined by M-mode echocardiography. The peak rate of change of the long-axis dimension of the LV during diastole as determined by cineangiography was significantly greater in the S3'(+) group than in the S3'(-) group. However, there was no significant difference between the two groups regarding the peak rate of change in the short-axis dimension of the LV during diastole as determined by cineangiography. The amplitude of the early diastolic dip of the interventricular septum (IVS) was significantly greater in the S3'(+) group as compared with that of the S3'(-) group. The amplitude of the S3' and the size of the RF wave correlated positively with the amplitude of the early diastolic dip of the IVS in pts with atrial fibrillation. Fractional shortening of the LV ascertained by M-mode echocardiography was significantly greater in the S3'(+) group than in the S3'(-) group. The end-systolic dimension of the LV tended to be less in the former than in the latter group. In conclusion, the S3' in MS was considered to be a third heart sound. Expansion along the long-axis of the LV and its sudden change in early diastole may account for the genesis of the S3', and this expansion may be accentuated by restoring force and active diastolic suction of the LV, and by velocity, direction and spread toward the cardiac apex of the stenotic mitral jet flow.