Abstract
Systolic time intervals and cardiac output were measured in 10 normal subjects (group I), 25 patients with angina pectoris (group II) and 32 patients with old myocardial infarction who were subdivided into 3 groups (group III : ejection fraction (EF) ⩾50% without congestive heart failure (CHF), group IV : EF < 50% without CHF and group V with CHF irrespective of the level of EF). Because the number of the patients of group V was too small and only this group was undergoing treatment during the study, the results obtained from this group were used for comparison only. The ET/PEP ratio was 2.41 ± 0.28 in group I, 2.70 ± 0.34 in group II (p < 0.02 as compared with group I), 2.35 ± 0.30 in group III and 2.11 ± 0.18 in group IV (p < 0.01 as compared with group I). The ejection time (ET) showed no significant difference between group I and group III or IV. The pre-ejection period (PEP) showed no significant difference between groups I and II. In groups III and IV, the PEP was prolonged as the EF decreased. These results indicate that the increase of the ET/PEP ratio in group II was mainly due to the prolongation of the ET, and the decrease of the ET/PEP ratio in group IV was not directly related to the ET but to the PEP prolongation. Both the stroke index (SI) and the mean systolic ejection rate (MSER) in groups III and IV were significantly low as compared with those in group I, but those in group II showed no significant difference as compared with those in group I. These findings suggest that the prolongation of ET in groups II, III and IV indicates a compensatory mechanism to maintain the SI.
