A case report of a 2-year-old boy who developed severe post-operative low cardiac output, sudden cardiac arrest and consecutive multiple organ system failure after open heart surgery is described. Initially the hemodynamic situation was stabilized by extracorporeal membrane oxygenation (ECMO) combined with continuous hemofiltration (CHF) carried out for 7 days. Continuous veno-venous hemofiltration (CVVH) was necessary for further 17 days. One episode of plasmapheresis restored transiently a severe post-operative coagulopathy and enabled the removal of the pulmonary artery catheter and the chest tubes.