Effects of Amrinone on Systemic and Pulmonary Arterial Pressure in Infants with Intracardiac Left to Right Shunt

Um, Sang Yong; Chung, Chan Jong; Chin, Young Jun

Abstract

BACKGROUND: Amrinone is a nonglycosidic noncatecholamine with both vasodilator and positive inotropic effects that has not been evaluated widely in pediatric patients with intracardiac left to right shunts. The present study was performed to evaluate the hemodynamic effects of amrinone in infants and children with intracardiac left to right shunts.
METHODS
Twenty patients (aged 2 months to 24 months) who underwent open heart surgery to correct one or more intracardiac left to right shunts were evaluated. Before cardiopulmonary bypass, a 22 gauge angiocatheter was placed at the main pulmonary artery by surgeons to measure pulmonary arterial pressure. Patients with a mean pulmonary arterial pressure < 25 mmHg were assigned to Group A (n = 10) and > or = 25 mmHg were assigned to Group B (n = 10). Mean systemic arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP) and heart rate (HR) were measured before loading of amrinone (3 mg/kg), 5 minutes, and 15 minutes after continuous infusion of amrinone (10 microgram/kg). The mean pulmonary arterial pressure to mean systemic arterial pressure ratio (MPAP/MAP) and rates of changes of mean arterial pressure (delta MAP) and mean pulmonary arterial pressure (delta MPAP) were calculated.
RESULTS
Amrinone reduced MAP, MPAP, CVP and increased HR. MPAP/MAP increased in Group A but decreased in Group B (P < 0.05). In Group A, delta MAP was significantly greater than that of Group B (P < 0.005). In Group B, delta MPAP was significantly greater than that of Group A (P < 0.005).
CONCLUSION
In infants with intracardiac left to right shunts, amrinone reduces MAP, MPAP, CVP and increases HR. Amrinone appears to have a potent vasodilating effect on the pulmonary artery in infants with pulmonary hypertension. However, more hemodynamic measurements such as cardiac output, vascular resistance and doppler echocardiographic study are necessary to evaluate the hemodynamic effects of amrinone precisely.