[Tolerance development during a 1-week course of dobutamine treatment]

Eleven patients with chronic heart failure (NYHA stage III or IV) were given dobutamine infusions over 7 days, mean dose 6.2 +/- 2.2 micrograms/kg X min. The patients were pretreated with digitalis, diuretics, and vasodilators. Haemodynamic parameters were measured prior to infusion, 30 minutes and 7 days thereafter as well as 24 hours after the end of therapy. Before and after the 7-day therapy a two-dimensional echocardiogram was taken. In four patients, the protocol had to be discontinued prematurely for technical or medical reasons.

Arterial blood pressure, body weight, fractional shortening and end-diastolic diameter of the left ventricle were not changed significantly. Cardiac index rose acutely and returned to initial values after 7 days. Total peripheral resistance, which was initially significantly reduced, again rose after infusion over 7 days. Permanent reduction in pulmonary artery wedge pressure, even one day after the end of therapy, was observed in three patients showing a left-ventricular end-diastolic wall thickness greater than 7 mm. However, in patients whose wall thickness was less than 7 mm, there was a rise in pulmonary artery wedge pressure accompanied by a fall in cardiac index even below initial values.