The short- and long-term hemodynamic effects of intravenous dopexamine hydrochloride (Dopacard) were studied in 12 patients with low cardiac output left ventricular heart failure. In the short-term study, a dose of 4 micrograms/kg/min produced a 60% increase in cardiac output (p less than 0.001), a 30% increase in stroke volume (p less than 0.01), a 23% increase in heart rate (p less than 0.01) and a 39% decrease in systemic vascular resistance (p less than 0.001). In the long-term study, there was a sustained hemodynamic benefit after 8 hours of dopexamine hydrochloride infusion (mean dose 3.5 micrograms/kg/min). There was a 32% increase in cardiac output (p less than 0.001), an 18% increase in stroke volume (p less than 0.05), a 12% increase in heart rate (p less than 0.001) and a 30% decrease in systemic vascular resistance (p less than 0.01). After 48 hours of dopexamine hydrochloride infusion (mean dose 3.8 micrograms/kg/min), the hemodynamic effect was significant only for cardiac output (+20%, p less than 0.05) and for systemic vascular resistance (-26%, p less than 0.01). Thus, dopexamine hydrochloride has beneficial short-term hemodynamic effects in patients with low-output left ventricular heart failure and the benefit appears to diminish with long-term infusion.