SELECTIVE PULMONARY AND SYSTEMIC VASODILATOR EFFECTS OF AMRINONE IN CHILDREN - NEW THERAPEUTIC IMPLICATIONS

Objectives. The present study was performed to determine the systemic and pulmonary hemodynamic effects of amrinone in infants and children with a cardiac left to right shunt to determine if there is a benefici al effect on the pathophysiology of this condition. Background. Amrino ne is a bipyridine derivative with inotropic and vasodilator effects t hat have not been systematically evaluated in the pediatric patient wi th increased pulmonary blood flow. Methods. Nineteen patients (aged 2 months to 8.3 years) with one or more left to right shunts were evalua ted during cardiac catheterization with direct hemodynamic measurement s made before and 10 min (peak effect) after administration of a bolus injection of amrinone, 3 mg/kg body weight. The Fick method was used to calculate pulmonary and systemic blood flow, and resistances were t hen calculated. Results. In group A, five patients with normal pulmona ry artery pressure and resistance, amrinone significantly reduced mean pulmonary artery pressure by 19%, mean left atrial pressure by 39% an d systemic vascular resistance by 17%. In group B, seven patients with pulmonary artery hypertension (mean pulmonary artery pressure >20 mm Hg) and normal pulmonary vascular resistance (total pulmonary resistan ce less-than-or-equal-to 3 Wood U.m2), amrinone significantly reduced the pulmonary artery pressure by 27%, systolic aortic pressure by 5%, mean aortic pressure by 12%, pulmonary arteriolar resistance by 36% an d total pulmonary vascular resistance by 26%. In group C, seven patien ts with pulmonary artery hypertension (mean pulmonary artery pressure >20 mm Hg) and elevated pulmonary vascular resistance (total pulmonary resistance >3 Wood U.m2), amrinone significantly reduced the pulmonar y arteriolar resistance by 49%, total pulmonary resistance by 47% and pulmonary arteriolar/systemic vascular resistance ratio by 45% and inc reased the heart rate by 15%. Conclusions. In children with a cardiac left to right shunt, amrinone 1) appears to have selective vasodilator effects depending on the pulmonary artery pressure and resistance, 2) has a beneficial hemodynamic effect in children with normal pulmonary artery pressure and resistance, and 3) may have a role in the treatme nt of patients with pulmonary artery hypertension without causing syst emic hypotension.