The haemodynamic effects of ketanserin versus dihydralazine in severe early-onset hypertension in pregnancy

Objective To compare the haemodynamic efficacy of ketanserin (a selective serotonin(2)-receptor blocker) with dihydralazine in the management of severe early-onset hypertension in pregnancy. Design Subgroup analysis within a randomised prospective multicentre trial to compare haemodynamic effects as measured by pulmonary artery catherization. Setting Departments of Obstetrics and Gynaecology and Intensive Care Medicine, Free University Hospital, Amsterdam and Sophia Hospital, Zwolle. Participants Thirty-one women with a diastolic blood pressure > 110 mmHg and a gestational age between 26 and 32 weeks. Results The antihypertensive efficacy of both drugs was comparable. Dihydralazine significantly increased cardiac output (P < 0.01), while ketanserin induced only minor changes in cardiac output. Systemic vascular resistance decreased in both groups, but the decrease was significantly more pronounced with dihydralazine compared with ketanserin. Ketanserin induced a significant but not clinically relevant increase in heart rate (P < 0 01, while dihydralazine caused marked tachycardia (P < 0.005). Left ventricular stroke work index was reduced to similar values in both groups. Conclusions The antihypertensive profile of ketanserin is characterised by an early and gradual reduction of blood pressure in combination with a moderate decrease in systemic vascular resistance and no significant change in cardiac output. Dihydralazine causes market tachycardia resulting in a considerable increase in cardiac output.