To evaluate the doses of hydralazine needed to obtain significant hemodynamic responses in severe chronic refractory heart failure, 45 consecutive patients received incremental doses of the drug during invasive hemodynamic monitoring. Twenty-six patients (group A) responded to the oral administration of single doses of 100 mg of hydralazine, whereas 19 patients (42 percent) (group B) did not. Of the patients in group B, 14 responded to 150 to 300 mg orally as a single dose, 3 patients required a single dose of 600 or 800 mg orally and 2 patients responded only to intravenous administration of the drug. In spite of the different dosage requirements of hydralazine, the hemodynamic responses to effective doses were similar in the two groups. The control etiologic, pathophysiologic and hemodynamic variables were similar in both groups, except that patients in group B had higher control values for mean right atrial pressure (14.0 ± 1.5 versus 9.2 ± 1.3 mm Hg; p <0.025) and left ventricular filing pressure (25.2 ± 1.2 versus 21.7 ± 1.0 mm Hg; p <0.05) than patients in group A. Twenty-one of 29 patients (72 percent) with a control mean right atrial pressure of less than 14 mm Hg responded to 100 mg of hydralazine, whereas this dose was effective in only 5 (31 percent) of 16 patients with a higher pressure value (p <0.02). In conclusion, the doses required for effective hydralazine therapy in patients with severe heart failure are variable and are generally higher than those utilized in hypertensive patients. This may be related to varying degrees of vascular hyporesponsiveness or drug malabsorption, or both, observed in states of high venous pressure. The failure of hydralazine to produce clinical improvement in an individual patient may therefore be due to the administration of subtherapeutic quantities of the drug.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine