Disparate cardiac effects of afterload reduction in hypertension.

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.