Early cardiovascular changes with ibopamine: evidence for a biphasic haemodynamic action.

1. The haemodynamic effects of ibopamine, an oral dopamine derivative, were studied in eight patients with left ventricular dysfunction using invasive catheterisation techniques. 2. An early rise was seen in the mean right atrial pressure (P less than 0.05), the mean capillary wedge pressure (P less than 0.01) and the mean pulmonary arterial pressure (P less than 0.001) which occurred at 15 min and persisted for 30 min. 3. A second, later, positive chronotropic effect was seen as an increase in the heart rate (P less than 0.05) at 45 min with an increased cardiac output (P less than 0.05) persisting above baseline values at 1 h, but with no change in stroke volume. 4. These results support a biphasic mode of action for ibopamine which may be explained by a time phase difference in alpha- and beta-adrenoceptor stimulatory effects.