The Heart-Lung Machine 1953 – Safe Complex Operations

A heart-lung machine (HLM) is a device that maintains blood circulation and adequate blood oxygen levels during procedures such as repairing heart valves or holes in the heart's internal wall. This process, called cardiopulmonary bypass, bypasses the heart and lungs and, together with chemicals that temporarily stop the heart, allows the surgeon to operate in a relatively bloodless, motionless environment. Heparin is used to reduce clotting in the circulating blood, and the blood may be cooled to slow the body's metabolism, reducing its need for oxygen.

In 1953, American surgeon John Gibbon became the first person to use an HLM successfully while repairing a hole in the internal wall of an 18-year-old woman's heart. Her heart and lungs were stopped for 27 minutes during the repair.

Innovative approaches were needed to reduce the potential damage an artificial pump could cause to red blood cells. For example, scientists experimented with roller pumps that gently moved blood through tubes and centrifugal pumps that created a pumping action by spinning the blood. More difficult than replacing the heartbeat was the need to replace the lungs' oxygenating function temporarily. Historical solutions included bubbling oxygen through the blood (and then filtering out the bubbles) and using membranes. 

In a natural lung, the intricate surfaces across which oxygen and carbon dioxide are exchanged have a total area roughly equivalent to one side of a tennis court! 

Some patients have reported a decline in mental abilities after the use of an HLM. Since this can also occur in patients with similar cardiovascular risk factors, the HLM may not be the cause of these losses. 

According to author Autumn Stanley, the HLM is "one of the most important device inventions in recent medical history, making possible all open-heart surgery, longer surgical procedures in general, and heart and heart-lung transplants."

Description of the Article Image: A reconstruction of a heart operation from the 1980s. This realistic model is displayed in the Lower Wellcome Gallery of London's Science Museum.

Historical Figures Mentioned in This Article: John Heysham Gibbon Jr. (1903–1973)

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