Heart-Lung Machine: Seven Decades of Challenging Work

Heart-lung machine (HLM), also called oxygenator pump or cardiopulmonary bypass (CPB) pump (Figure 1), aims to provide extracorporeal circulation (ECC) with maintenance of oxygenated blood flow to the body organs when the device is connected to the arteriovenous system. The HLM is an essential component of openheart surgery to bypass the circulatory system of the heart and lungs, termed CPB. The main principle is to draw the blood from the major veins (venae cavae) to an oxygenator in the HLM where it is re-oxygenated, and then pumped into the arterial system (ascending aorta). Additionally, the myocardial contractility during CPB can be halted by running a cardioplegic solution containing potassium citrate. The initial concept to constitute an artificial circulation and hence CPB was stated in the 19th century on the basis that the contractility of muscle could be restored by perfusion of an oxygenated blood under pressure to enable better perfusion of isolated organs. Therefore, there was a need to develop an artificial heart-lung system to perfuse an oxygenated solution without interruption of blood flow, which became a real in the beginning of the 20th century after discovery of the ABO blood group system to reduce inconveniences of incompatibility, in addition to discovery of heparin to inhibit coagulation [1].