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The effect of intravenous captopril on right and left ventricular load and function in moderate-severe essential
1Division of Cardiology, Taichung Veterans General Hospital, Taiwan, Republic of China.
Insights
Intravenous captopril rapidly reduces blood pressure in hypertensive patients by dilating blood vessels. This effective treatment for severe hypertension shows minimal adverse effects and a quick onset of action.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Hypertension poses significant cardiovascular risks.
- Effective and rapid-acting antihypertensive agents are crucial for managing hypertensive emergencies.
Purpose of the Study:
- To evaluate the acute hemodynamic effects and left ventricular function following intravenous captopril administration in patients with moderate to severe hypertension.
Main Methods:
- Eleven patients with moderate to severe hypertension received escalating doses of intravenous captopril.
- Hemodynamic parameters and left ventricular function were assessed using radionuclide angiography.
Main Results:
- Intravenous captopril induced rapid blood pressure reduction in 8/11 patients, with onset within 5 minutes and peak effect at 5-10 minutes.
- Effects included reduced systemic vascular resistance, right atrial pressure, and pulmonary wedge pressure.
- Isovolumic relaxation period lengthened, and coronary perfusion pressure gradients decreased significantly (P < 0.001).
Conclusions:
- Intravenous captopril is effective for rapid arterial pressure reduction in severe hypertension with minimal adverse effects.
- The drug's hemodynamic profile suggests potential utility as an alternative treatment regimen.
- Prolongation of isovolumic relaxation period contributes to decreased coronary filling load.
Abstract:
The acute haemodynamic effects of intravenous captopril were measured, and left ventricular function was analysed by radionuclide angiography in eleven patients with moderate to severe hypertension. All subjects received 1 mg captopril by bolus injection initially, followed at 10 minute intervals by 2 mg or 5 mg injections according to blood pressure response. Eight patients experienced an acute reduction of blood pressure whilst three patients remained unresponsive. The onset of action was within 5 minutes with a peak effect at 5 to 10 minutes and duration of action lasting 20 to 30 minutes. The haemodynamic effects were characterised by arteriolar dilatation (reduced systemic vascular resistance P less than 0.01), and apparent venous dilatation (reduced right atrial, pulmonary wedge pressure, P less than 0.05 and 0.01 respectively). Pulmonary vascular resistance was not altered, ejection fraction remained unchanged and isovolumic relaxation period was lengthened (119 +/- 20.1 to 147.39 +/- 21.15, P less than 0.05). Coronary perfusion pressure gradients dropped (123.8 +/- 5.6 to 107.1 +/- 11.3 mmHg, P less than 0.001) following intravenously administered captopril. Intravenous captopril is effective in reducing arterial pressure rapidly with minimal adverse effects. This suggests that it may be useful as an alternative regimen for severe hypertension. The prolongation of the isovolumic relaxation period accounted for the decrease of coronary filling load.