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Disparate cardiac effects of afterload reduction in hypertension
C Amodeo1, F H Messerli, H O Ventura
1Department of Internal Medicine, Ochsner Clinic, New Orleans, Louisiana 70121.
Insights
Dopamine agonist fenoldopam improved cardiac contractility in hypertensive patients, unlike calcium entry blockers or ACE inhibitors. Fenoldopam also reduced preload, while all tested antihypertensives lowered blood pressure and afterload.
Area of Science:
- Cardiology
- Pharmacology
- Hypertension Research
Background:
- Essential hypertension affects cardiac performance.
- Understanding the effects of antihypertensives on cardiac function is crucial.
Purpose of the Study:
- To evaluate the impact of different antihypertensive agents on cardiac performance in patients with essential hypertension.
- To compare the effects of calcium entry blockers, ACE inhibitors, and a dopamine receptor agonist on preload, afterload, and myocardial contractility.
Main Methods:
- Non-invasive M-mode echocardiography was used to assess cardiac parameters.
- Patients with mild to moderate essential hypertension received oral nitrendipine, verapamil, captopril, lisinopril, or fenoldopam.
- Left ventricular end-diastolic volume, end-systolic stress, SBP:ESV, ejection fraction (EF), and Vcf were measured.
Main Results:
- All agents reduced afterload (15%) and mean arterial pressure (10%).
- Lisinopril showed the greatest afterload reduction (21%).
- Fenoldopam decreased preload by 24% and significantly increased myocardial contractility parameters (SBP:SV 66%, EF 17%, Vcf 19%).
- Calcium entry blockers and ACE inhibitors did not affect myocardial contractility parameters.
Conclusions:
- Fenoldopam demonstrates beneficial effects on cardiac contractility and preload in hypertensive patients.
- While effective in reducing afterload, calcium entry blockers and ACE inhibitors do not enhance myocardial contractility.
- Dopamine receptor agonists represent a potential therapeutic avenue for improving cardiac function in hypertension.
Abstract:
Cardiac performance, as judged by preload, afterload, and myocardial contractility, was evaluated by non-invasive M-mode echocardiography before and after acute oral administration of calcium entry blockers (nitrendipine and verapamil), angiotensin converting enzyme (ACE) inhibitors (captopril and lisinopril), and a dopamine receptor agonist (fenoldopam) in patients with mild to moderate essential hypertension. Left ventricular end diastolic volume was taken as an index of preload, end systolic stress as an index of afterload, and the ratio of systolic pressure to end systolic volume (SBP:ESV), ejection fraction (EF), and mean velocity of circumferential fibre shortening (Vcf) as indices of contractility. Reductions of afterload and mean arterial pressure were achieved with all antihypertensive agents involved (mean percentage change +/- s.e.m.: 15 +/- 2% and 10 +/- 1%, respectively, P < 0.05) but the afterload reduction with lisinopril was greatest (21 +/- 9%; P < 0.01). The dopamine receptor agonist fenoldopam decreased by preload 24% (P < 0.05) and increased all of the three parameters of myocardial contractility (SBP:SV 66%; EF 17%, Vcf 19%; P < 0.01). In contrast, no effect on these parameters was observed with either calcium entry blocker or either ACE inhibitor.