The authors assessed the effect of enoximone and milrinone on cardiac function in paediatric patients with postoperative low cardiac output syndrome. Twenty five patients with low cardiac output syndrome following cardiac surgical treatment were studied between January 2000 and November 2003, age range between 0.2 and 40 months (median 8 months) and weight between 2.7 and 13.7 kg (median 8.4 kg). Echocardiographic, Doppler derived, time interval based index of myocardial performance was used to study cardiac function prior to and while on intravenous enoximone or milrinone treatment for 12–24 hours. Deterioration of right and left ventricular myocardial function as assessed by myocardial performance index was observed in the nine patients treated with enoximone (mean right ventricular index from 0.4, SD 0.177, to 0.658, SD 0.183, p=0.007, mean left ventricular index from 0.384, SD 0.192, to 0.578, SD 0.244, p=0.003). Treatment with milrinone led to improvement in biventricular myocardial function (mean right ventricular index from 0.521, SD 0.213, to 0.385, SD 0.215, p=0.003, and mean left ventricular index from 0.636, SD 0.209, to 0.5, SD 0.171, p=0.012) in the remaining 16 patients. No difference was found in the values of heart rate corrected right or left ventricular ejection time in patients prior to and while on treatment with milrinone (right ventricle: mean 1.23, SD 0.42 and 1.14, SD 0.48, p=0.29; left ventricle: mean 1.17, SD 0.51 and 1.13, SD 0.48, p=0.66). The direct myocardial effect of milrinone forms part of the mechanism behind its already proven clinical benefit in children with low cardiac output syndrome following cardiac surgery.

        Key words: congenital heart defect, operation, myocardial function, phosphodiesterase inhibitors