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Long-term hemodynamic effects of antihypertensive treatment
P Lund-Johansen1, P Omvik, J E Nordrehaug
1Medical Department, University of Bergen, School of Medicine, Haukeland Hospital.
Insights
Essential hypertension involves high total peripheral resistance and abnormal heart function during exercise. Carvedilol effectively manages blood pressure, reducing peripheral resistance and improving cardiac function without significant negative effects.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Background:
- Essential hypertension is characterized by increased total peripheral resistance and impaired cardiac function during exercise.
- Long-term hypertension leads to progressive increases in total peripheral resistance and cardiac pump dysfunction.
- Antihypertensive medications have varied effects on circulatory hemodynamics.
Purpose of the Study:
- To evaluate the hemodynamic effects of carvedilol, a combined alpha and beta-blocker, in patients with essential hypertension.
- To compare the hemodynamic profile of carvedilol with conventional beta-blockers and vasodilators.
Main Methods:
- Hemodynamic measurements were taken over 6-9 months in 19 patients treated with carvedilol.
- Exercise testing was performed to assess cardiac output, heart rate, and stroke volume.
- Echo-Doppler studies were utilized to evaluate cardiac structure, specifically the intraventricular septum.
Main Results:
- Carvedilol effectively controlled blood pressure in patients with essential hypertension.
- During exercise, carvedilol led to a significant decrease in total peripheral resistance (6%) and less reduction in heart rate and cardiac index compared to conventional beta-blockers.
- Echo-Doppler revealed a significant 13% reduction in intraventricular septum thickness.
Conclusions:
- Carvedilol demonstrates favorable hemodynamic effects in essential hypertension, reducing total peripheral resistance and improving cardiac function during exercise.
- Unlike conventional beta-blockers, carvedilol mitigates the adverse effects on cardiac output and heart rate.
- Carvedilol represents a valuable therapeutic option for managing essential hypertension with associated cardiac remodeling.
Abstract:
The cardinal hemodynamic disorder in established essential hypertension is increased total peripheral resistance. During exercise, the increase in stroke volume of the heart is abnormal. A 20-year follow-up study of the hemodynamics in essential hypertension demonstrated a progressive increase in total peripheral resistance and deterioration of the heart pump function. Long-term treatment with antihypertensive agents modifies the circulatory system in different ways. Vasodilators (angiotensin converting enzyme inhibitors, alpha 1-blockers, and calcium antagonists) all reduce total peripheral resistance, and in general, cardiac output, heart rate, and stroke volume remain unchanged. Calcium antagonists like verapamil and diltiazem reduce the heart rate approximately 10% during exercise, but since stroke volume increases, cardiac output is unchanged. Chronic treatment with conventional beta-blockers induces a permanent reduction in cardiac output and heart rate during exercise. In contrast, carvedilol--a beta 1,beta 2-blocker with alpha 1-blocking activity--prevents the immediate increase in total peripheral resistance during acute beta-blockade. In 19 patients followed by hemodynamic measurements over 6-9 months, blood pressure was well controlled by carvedilol. During exercise, total peripheral resistance decreased 6% (P less than 0.05), and the reductions in heart rate and cardiac index were less than on conventional beta-blockade. Echo-Doppler studies showed a significant reduction in the intraventricular septum of 13%.