[Role of dihydralazine in the treatment of chronic cardiac insufficiency].

Dihydralazine, sold under the name of Nepressol, is the derivative of the hydrazinophthalazines used in France for the treatment of severe cardiac failure. The hydrazinophthalazines act in cardiac failure by decreasing systemic arterial resistance and increasing cardiac output without causing tachycardia or increasing myocardial contractility in normal or hypotensive subjects. The hydrazinophthalazines are metabolised by N-acetyl-transferase in the liver. The hepatic concentration of this enzyme is genetically determined. The immediate haemodynamic results observed with 100 to 300 mg/daily of Nepressol are impressive: an 86 p. 100 increase in cardiac output; a 75 p. 100 decrease in systemic valvular resistance; a 25 p. 100 fall in left ventricular filling pressures. These haemodynamic results are maintained at long-term (3 to 48 months). This treatment is associated with an improvement in symptoms and functional capacity. However, its efficacy in improving survival has not been demonstrated. Immunological complications giving rise to a lupic syndrome result only in biological changes and do not influence management.