The analysis of the blood flow pattern in the left ventricle during isovolumic relaxation period was performed in 20 patients with hypertrophic cardiomyopathy (HCM) and 15 normal subjects using pulsed Doppler echocardiography. In normal subjects, this flow was directed toward the apex and had the maximal velocity at the central area of the left ventricle. In HCM, the flow pattern could be divided into three types; type A (n=11), flow directed toward the apex; type B (n=l), toward the base; type C (n=2), diminished flow; and in the other 6 patients, no clear signal could be detected. The patient of type B with HCM had akinetic wall motion at the anterior and apical region revealed by left ventriculography. In type C, the ejection fractions were decreased. The blood flow patterns in type A were compared with those of normal subjects. The time interval from the start to the peak of the flow (Acceleration Time, AcT) and the duration of the flow (Isovolumic Relaxation Time, IRT) were significantly prolonged in HCM than in normal subjects, and the slopefrom the start to the peak (Acceleration Rate, AcR) was significantly depressed in HCM.
In conclusion, the blood flow during isovolumic relaxation period was produced by left ventricular relaxation. And it could give us a new useful information for assessing left ventricular relaxation property.