An infant, 2 months old, underwent cardiac surgery because of congenital heart defects and pulmonary hypertension. Surgery was performed in hypothermia and cardiac standstill. On the second day after surgery the infant had to be resuscitated due to a combination of acute left-ventricular failure, pulmonary vascular hypertension and a slight right-to-left-shunt. A breakthrough in the treatment was achieved by using levosimendan to improve left-ventricular function and to decrease vascular resistance.