Studies on Circulatory Dynamics during Bicycleergometer Exercise in Patients with Essential Hypertension

Hemodynamic parameters including systolic time intervals were evaluated non-invasively at recumbent rest and during uninterrupted multi-graded exercise with a sitting bicycle ergometer in thirty-three men with essential hypertension and thirty-five healthy men by Minnesota impedance cardiography.Subjects were subdivided with age: group NI, comprised 24 normotensives under 40: group NII,11 normotensives from 40 to 60: group HI,13 untreated hypertensives under 40: group HII,20 untreated hypertensives from 40 to 60.Exercise was started at 25 watts for three minutes and increased by 25 watts every three minutes.1) At recumbent rest: Group NII showed higher diastolic blood pressure, lower SI/ET (left ventricular mean ejection rate) and (SI/ET) /PEP ratio than group NI. There were no significant differences in other hemodynamic parameters between the normotensive groups. Both hypertensive groups showed lower stroke index, cardiac index, higher total peripheral resistance and longer PEP than the age-matched normotensives. Group HI showed higher heart rate, shorter LVET and Q-IIA interval than group NI. These findings indicate that the hypertensives have increaed resistance to left ventricular ejection and that in group HI, the increased sympathetic stimulation may play a part in maintaining the elevated blood pressure.2) During exercise: The increment of stroke ind ex, cardiac index, SI/ET and the decrement of total peripheral resistance were greater in the middle-age groups than in the young-age groups. These findings indicate that the middle-age groups have inproper blood distribution during exercise. The (SI/ET) /PEP ratio, which is thought to demonstrate the reactivity of left ventricle, increased identically in all groups. The changes of systolic time intervals were not significantly different among each group. These findings indicate that although the resistance to left ventricular ejection had increased in the hypertensive groups, the cardiac function itself was maintained in the normal range.