The “benefits” of the mini-extracorporeal circulation in the minimal invasive cardiac surgery era

Mini-extracorporeal circulation (MECC) constitutes a novel miniaturized cardiopulmonary bypass (CPB) circuit, heparin-coated and primed with aprotinin. Its membrane oxygenation is similar to conventional cardio-pulmonary bypass (CCPB), but it is a completely closed-volume system due to the lack of the venous reservoir which has been removed. In a mini circuit, the reservoir is the patient himself. Consequently, air entering the venous cannula is avoided. Nevertheless, the capabilities of MECC have been expanded either by the inclusion of a suction device that is only activated on direct contact with liquid in some circuits or by postoperative autotransfusion of the wrecked erythrocytes by a separate suction device with a cell-saver. Although the tubing diameter is similar between the two systems, the tubing length of the MECC is around half that of the CCPB, resulting in the restriction of priming volume. As a consequence, a higher hematocrit thus a limited need for perioperative blood transfusion is achieved due to less hemodilution. In addition, the inflammatory response is also diminished as a result of less artificial surface area interacting with blood. Finally, a lower dose of heparin is required prior to MECC than prior to CCPB.