Acute hemodynamic effects of nitroprusside in children with isolated mitral regurgitation

Abstract

The acute hemodynamic responses to nitroprusside during cardiac catheterization were evaluated in 12 children with isolated mitral regurgitation (MR) of congenital origin. The patients were classified into 2 groups. Group 1 consisted of 5 patients who received digitalis or diuretic drugs and group II consisted of 7 patients who received no medication. Hemodynamic measurements were performed using a multisensor catheter system during infusion of nitroprusside at a dose of 2.0 μg/kg/min. With nitroprusside, the mean right atrial pressure decreased an average of 50% in group I (from 6 ± 1 to 3 ± 1 mm Hg) and 75% in group II (from 4 ± 1 to 1 ± 1 mm Hg), and the mean decrease of pulmonary artery wedge pressure was 50% in group I (from 14 ± 3 to 7 ± 3 mm Hg) and 56% in group II (from 9 ± 2 to 4 ± 1 mm Hg). Administration of nitroprusside also caused a significant reduction in systemic vascular resistance by 40% in both groups (from 25 ± 6 to 15 ± U/m 2 in group I and from 25 ± 2 to 15 ± 3 U/m 2 in group II), whereas forward cardiac output increased markedly, by an average of 48% in group I (from 3.3 ± 0.5 to 4.9 ± 0.9 liters/min/m 2) and 58% in group II (from 3.3 ± 0.3 to 5.2 ± o.8 liters/min/m 2). No significant differences in hemodynamic response between groups I and II were noted. These data indicate that nitroprusside augments forward ejection associated with decrease in regurgitant flow as a results of reductions in preload and afterload regardless of the severity of MR. It is concluded that vasodilator therapy may be beneficial for selected infants and children with MR.