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Cardiac function of patients with essential hypertension during exercise and isoproterenol infusion
Insights
Essential hypertension impairs left ventricular diastolic function at rest, worsening with cardiac hypertrophy or dilatation. Some patients show early signs of systolic dysfunction during exercise or isoproterenol (ISP) infusion.
Area of Science:
- Cardiology
- Cardiovascular Physiology
- Hypertension Research
Background:
- Essential hypertension is a major risk factor for cardiovascular disease.
- Left ventricular (LV) function can be affected by hypertension, but the specific impact on diastolic and systolic function requires further investigation.
Purpose of the Study:
- To evaluate left ventricular diastolic and systolic function in patients with essential hypertension.
- To assess the effects of exercise and isoproterenol (ISP) infusion on LV function in hypertensive individuals.
Main Methods:
- Utilized M-mode echocardiography to assess LV function at rest, during exercise, and during ISP infusion.
- Studied four groups: normotensives (Group N), hypertensives without cardiac hypertrophy (Group NH), with cardiac hypertrophy (Group HH), and with cardiac dilatation (Group D).
- Administered multistage exercise via a supine bicycle ergometer and ISP infusion at varying doses.
Main Results:
- At rest, hypertensive groups showed prolonged isovolumic relaxation time (IRT), with Group HH and Group D having longer IRTs than Group NH.
- Only Group D exhibited significantly reduced shortening fraction (SF) at rest and during exercise.
- Group HH demonstrated impaired LV function during ISP infusion (reduced peak negative dD/dt) and a trend towards reduced SF during exercise.
Conclusions:
- Left ventricular diastolic dysfunction is present in all hypertensive groups at rest and worsens with cardiac hypertrophy or dilatation.
- Left ventricular systolic function is depressed at rest in Group D.
- Subtle systolic dysfunction may be present in Group HH, indicated by exercise and ISP infusion responses.
Abstract:
The left ventricular function of patients with essential hypertension was examined during exercise and isoproterenol (ISP) infusion echocardiography. Twenty-eight hypertensive patients without cardiac hypertrophy (Group NH), 20 patients with cardiac hypertrophy (Group HH), 7 patients with cardiac dilatation (Group D), and 13 normotensives (Group N), were studied during multistage exercise using a supine bicycle ergometer. In addition, 23 hypertensives (Group NH: 13 patients, Group HH: 10 patients) and 10 normotensives were studied during ISP infusion (0.005 microgram/kg/min, and 0.01 microgram/kg/min, respectively, for 5 min). To assess the left ventricular function, an M-mode echocardiogram was utilized at rest and during exercise and ISP infusion. At rest, the isovolumic relaxation time (IRT) of each hypertensive group was significantly longer than that of Group N. IRT of Group HH and Group D was significantly longer than that of Group NH. Only the shortening fraction (SF) of Group D was significantly smaller than that of Group N. During exercise the SF increased in all groups, and only the SF of Group D was significantly smaller than that of Group N at a load of 75 W as well as at rest. The SF of Group HH tended to be smaller. There was no significant difference in peak negative dD/dt (-dD/dt) between any of the groups at rest; however, the -dD/dt of Group HH was significantly smaller than that of Group N during ISP infusion. We concluded that left ventricular diastolic function was disturbed in each hypertensive group at rest. Diastolic dysfunction worsened in Group HH and Group D. Only the left ventricular systolic function of Group D was already depressed at rest. Furthermore, unmanifested systolic dysfunction of the left ventricle seemed to be present in Group HH, because SF during exercise tended to be smaller and -dD/dt during ISP infusion was significantly smaller than that of Group N.