Variable hemodynamic response to oral hydralazine in patients with refractory congestive heart failure*

Hydralazine, 200 to 400 mg daily, was administered orally to 20 consecutive patients with severe heart failure. After 24 h of continuous hydralazine therapy, an average fall in mean blood pressure of 9 mmHg (P < 0.01) was associated with an overall increase in cardiac index from 1.7 to 2.4 l/min/m2 (P < 0.001), and a reduction in pulmonary wedge pressure from 24 to 20 mmHg (P < 0.05). However, five of the 20 patients developed minimal or no changes in cardiac index while the remaining 15 demonstrated a rise in cardiac index of at least 30%. Initial systemic vascular resistance was significantly higher in patients without change in cardiac index than in those with an increase (2348 v. 1818 dyne.s.cm−5; P < 0.05), but could not be used to predict accurately the response to hydralazine therapy. Thus, hydralazine is generally beneficial in severe heart failure but the hemodynamic responses in individual subjects may vary. Hemodynamic monitoring is recommended in severely ill patients to evaluate responsiveness in anticipation of long-term maintenance therapy.