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The effect of intravenous captopril on the left ventricular function-an acute study by hemodynamics and radionuclide
Insights
Intravenous captopril effectively lowers blood pressure in hypertensive patients by dilating blood vessels. This treatment shows rapid action and minimal adverse effects, primarily impacting arteriolar dilation.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertension management requires effective antihypertensive agents.
- Understanding the acute hemodynamic effects of captopril is crucial for its clinical application.
Purpose of the Study:
- To evaluate the acute hemodynamic effects of intravenous captopril in patients with moderate to severe hypertension.
- To analyze left ventricular function following captopril administration.
Main Methods:
- 11 patients with hypertension received escalating doses of intravenous captopril.
- Hemodynamic parameters and left ventricular function were assessed using radionuclide angiography.
- Systemic vascular resistance, right atrial pressure, and pulmonary wedge pressure were measured.
Main Results:
- Eight patients showed an acute reduction in blood pressure; three were unresponsive.
- Captopril induced arteriolar dilation, reducing systemic vascular resistance (P < 0.01).
- Isovolumic relaxation period lengthened (P < 0.05) and coronary perfusion pressure gradients decreased (P < 0.001).
Conclusions:
- Intravenous captopril effectively reduces arterial pressure through arteriolar dilation with minimal adverse effects.
- The observed prolongation of isovolumic relaxation is likely due to decreased coronary filling load.
- Captopril demonstrates a rapid onset and short duration of action for acute blood pressure management.
Abstract:
Acute hemodynamic effects of intravenous captopril were measured, and left ventricular function was analyzed by radionuclide angiography in 11 patients with moderate to severe hypertension. All subjects received 1 mg captopril bolus injection initially, and followed in 10 minutes intervals by 2 mg or 5 mg injections according to their blood pressure response. Eight patients experienced an acute reduction of blood pressure; three patients remained unresponsive. The onset of action occurred within 5 minutes with peak effect at 5 to 10 minutes and a duration of action of 20 to 30 minutes. The hemodynamic effects were characterized by arteriolar dilation (reduced systemic vascular resistance P less than 0.01), and apparent venous dilatation (reduced right atrial, pulmonary wedge pressure P less than 0.05 & 0.01 respectively). Pulmonary vascular resistance was not altered. Ejection fraction remained unchanged. Isovolumic relaxation period lengthened (109 +/- 20.1 vs 137.39 +/- 21.15 msec, P less than 0.05) and coronary perfusion pressure gradients dropped (113.8 +/- 5.6 vs 101.1 +/- 11.3 mmHg P less than 0.001) following intravenously administered captopril. Intravenous captopril may reduce arterial pressure by inducing arterial dilatation with minimal adverse effect. The prolongation of isovolumic relaxation period should mainly attribute to the decrease of coronary filling load.