A heart-lung machine (also called a cardiopulmonary bypass machine or bypass pump) is the device used during open heart surgery to temporarily take over the functions of the heart and lungs. It draws blood from the right side of the heart, pumps it through an oxygenator (which adds oxygen and removes carbon dioxide), and returns the oxygenated blood to the arterial circulation, maintaining blood flow to the body’s organs while the heart is stopped and the surgeon operates inside it.
The heart-lung machine allows the heart to be stopped, emptied, and opened for surgery while the patient remains alive and their organs are perfused. It is operated by a specialist called a perfusionist, who adjusts the flow rate, temperature, oxygen delivery, and drug additions throughout the procedure. Most cardiac operations, including coronary artery bypass grafting, valve surgery, correction of congenital heart defects, and heart transplantation, rely on the heart-lung machine.
The machine transformed cardiac surgery since its first successful clinical use by Dr John Gibbon in 1953. Before its development, the interior of the beating heart was inaccessible to surgeons. Its introduction opened the era of open heart surgery and remains the basis for most complex cardiac operations today.
For detailed information on how the heart-lung bypass circuit works and its clinical implications, see Cardiopulmonary Bypass.
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