The Journal of Thoracic and Cardiovascular Surgery, Vol 80, 50-53, Copyright © 1980 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Afterload reduction with hydralazine following valve replacement
JD Marco, JW Standeven and HB Barner
Impedance reduction with hydralazine was evaluated in 23 patients 1 to 3
hours after aortic or mitral valve replacement. Patients were randomly
assigned to Group 1 (0.25 mg/kg) or Group 2 (0.5 mg/kg) and responses at
20, 60, and 120 minutes compared with control (paired t test) and mean
values for each group compared (t test). In Group 1 significant responses
were the fall in mean arterial pressure (78.3 +/- 3.0 to 66.7 +/- 2.2 mm
Hg) and systemic vascular resistance (2,808 +/- 264 to 1,823 +/- 164
dynes-sec/cm5); the increase in cardiac index (2.07 +/- 0.13 to 2.71 +/-
0.21 L/min/m2), stroke volume index (26.9 +/- 2.3 to 34.0 +/- 3.3 ml/beat),
and heart rate (80.8 +/- 5.8 to 84.2 +/- 6.6 beats/min). Central venous
pressure did not change and left atrial pressure decreased at 120 minutes.
Group 2 responses were similar except for higher central venous pressure at
20 minutes, higher left atrial pressures at control, 20, and 60 minutes,
and lower left ventricular stroke work at control, 20, and 60 minutes. By
selectively dilating the arterial system, hydralazine reduces mean arterial
pressure and systemic vascular resistance and increases cardiac output with
suble filling pressures.
