Value of systolic and diastolic time intervals. Studies in normotensive and hypertensive 50-year-old men and in patients after myocardial infarction.

SUmAMRY Systolic and diastolic time intervals were studied non-invasively in a group of untreated hypertensives (n = 19) and a reference group (n = 36), all derived from a random population sample of 50-year-old men, and in a myocardial infarct group (n = 67) representative ofmen aged 48 to 57 years surviving infarction. The results showed that only the electromechanical interval, pressure rise velocity, and the interval between the aortic component of the second heart sound (A2) and the 0-point in the apex cardiogram were useful discriminants between the three groups. There were no significant differences in systolic time intervals between the groups and the systolic time intervals were of limited diagnostic value as signs of impaired left ventricular function. The infarct patients had a significantly longer electromechanical interval (34 ms) than individuals in the reference group (27 ms), indicating delayed start of the systolic contraction in the infarction group. The pre-ejection period predicted the isovolumetric contraction time with great uncertainty in the infarct group. Increased pressure rise velocity (resting diastolic blood pressure/isovolumetric contraction time >1200 mmHg/s) was seen in 38 per cent of the infarct patients and 67 per cent of the hypertensives, compared with 4 per cent in the reference group, indicating more powerful contraction in infarct patients and hypertensives as compared with subjects in the reference group. The difference could not be explained by a difference in preload as judged from the a-wave in the apex cardiogram. The A20 interval was significantly prolonged (>150 ms) in 74 per cent of the infarct patients and 56 per cent of the hypertensives, as compared with 3 per cent in the reference group, indicating prolonged relaxation or prolongation of the early filling phase of the left ventricle in hypertensives and infarct patients. This was mainly related to factors other than heart rate and blood pressure.