The Journal of Thoracic and Cardiovascular Surgery, Vol 78, 195-202, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Specific afterload reduction with parenteral hydralazine following cardiac surgery
RN Sladen and MH Rosenthal
In a group of seven patients who had had cardiac operations, intravenous
(IV) hydralazine was used to provide afterload reduction in situations of
severe left ventricular dysfunction. Despite fluid loading, inotropic
support with dopamine, and afterload reduction with sodium nitroprusside,
the patients had persistent states of low cardiac output and high systemic
vascular resistance. Administration of sodium nitroprusside was limited by
its effect on preload and blood pressure, so that it necessitated frequent
fluid challenges. The addition of IV hydralazine to this regimen caused a
mean increase of 44.7% in the stroke index and a mean reduction of 28.6% in
systemic vascular resistance without significant change in pulmonary artery
wedge pressure, mean arterial pressure, or heart rate. Rapid weaning of
sodium nitroprusside and, on occasion, dopamine was facilitated. Frequent
fluid challenges to restore preload were unnecessary. Dose requirements of
hydralazine were small: 2.5 to 5.0 mg IV initially, and then a maintenance
dose of 2.5 to 7.5 mg IV every 4 to 6 hours. These preliminary clinical
observations indicate that in patients with low cardiac output--high
resistance states and normal or elevated preload, the important benefit of
specific afterload reduction may be provided by parenteral hydrolazine in
the early period following cardiac surgery. Prospective, controlled studies
with this agent in this situation appear warranted.
