Verma S P, Silke B, Hussain M, Nelson G I, Wilson J A, Reynolds G W, Richmond A, Taylor S H
University Department of Cardiovascular Studies, UK.
J Hypertens. 1988 Nov;6(11):897-904. doi: 10.1097/00004872-198811000-00008.
The haemodynamic impact of alpha- and beta-adrenoceptor blockade (labetalol) was compared with that of slow-calcium channel blockade (nifedipine) in 32 patients with sustained elevation of systemic arterial pressure (systolic blood pressure greater than 160; diastolic blood pressure greater than 95 mmHg) following a recent myocardial infarction (6-22 h). Patients with normal (pulmonary artery occluded pressure; (PAOP less than 18 mmHg; n = 16) or impaired (PAOP greater than 18 mmHg; n = 16) left ventricular function were randomized to labetalol (1 mg/kg i.v. 15 min) or nifedipine (20 mg sublingually) and haemodynamic profile was measured over 2 h. Both drugs equally reduced mean systemic arterial pressure (P less than 0.01 versus pretreatment control), and presumably left ventricular afterload; however, the heart rate (P less than 0.01) and cardiac index (P less than 0.01) increased after nifedipine, contrasting with reductions in both variables following labetalol (P less than 0.01). The elevated left ventricular filling pressure was reduced by both labetalol (P less than 0.05) and nifedipine (P less than 0.01) but the reduction was greater following nifedipine (-2 mmHg versus -5 mmHg, P less than 0.05). Thus both compounds were equally effective hypotensive agents. Labetalol consistently reduced cardiac stroke work and double product, important determinants of myocardial oxygen requirements; however, nifedipine afforded some improvement in cardiac performance in patients with left ventricular dysfunction.
