Dopexamine hydrochloride, a beta 2 adrenergic and dopaminergic agonist; haemodynamic effects following cardiac surgery.

Twelve patients recovering from open heart surgery received an intravenous infusion of dopexamine hydrochloride, a novel beta 2 adrenergic and dopamine receptor agonist. The mean cardiac index increased from 2.58 to a maximum of 3.64 1 min-1 m-2 (P less than 0.001) and the systemic vascular resistance (SVR) decreased from 1527 to 1116 dyne s cm-5 (P less than 0.001) at a dose of 3 micrograms kg-1 min-1. Heart rate increased with dose from 85 beats min-1 to a maximum of 119 beats min-1 (P less than 0.001). There was no significant change in the pulmonary vascular resistance (PVR) with treatment in the group as a whole. However, PVR decreased (P less than 0.05) in patients who had aortic-valve replacement (AVR) only, whereas in patients who had mitral-valve replacement (MVR) the PVR increased (P less than 0.05). We conclude that dopexamine hydrochloride was well tolerated in patients following cardiac surgery. It produced a significant increase in cardiac output with evidence of afterload reduction and, although the increase in heart rate may limit its use in some patients, dopexamine hydrochloride is potentially of value in the treatment of low cardiac output state following cardiac surgery.