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The maximalrate of reduction of the left ventricular pressure (peak negative dp/dt) was studied in 25 cases with hypertrophic cardiomyopathy (HCM), 4 cases with congestive cardiomyopathy (COCM) and 10 control subjects. Peak negative dp/dt was significantly less in HCM(972±286 mmHg/sec) and COCM(1181±437 mmHg/sec) than that in control subjects (2140±266mmHg/sec). A ratio of positive to negative peak dp/dt was increased in HCM alone, indicating a dissociation between positive and negative peak dp/dt. When the indices of distensibility and compliance were calculated by the method of Gaasch et al, significant correlations were observed between peak negative dp/dt and dV/dP (r=0.74, p>0.001) and between peak negative dp/dt·EEDP and dV/dP·V (r=0.91, p<0.001) in HCM and control subjects. Thus, peak negative dp/dt seemed to be affected by alterations in the diastolic properties of the left ventricle and to be a valuable index of left ventricular relaxation.
Toshima et al. (1976) studied this question.