Heart-Lung Machine

One of the major milestones in medicine was the development of artificial circulation, also known as heart-lung bypass. Before the heart-lung machine was invented, heart surgeons operated blindly, with the heart still pumping, or by slowly chilling the patient's body until circulation nearly stopped, or by connecting the patient's circulatory system to a second person's system during the operation. All of these methods were extremely risky.

Gibbon's Research

An American surgeon named John H. Gibbon Jr. (1903-1974), began pursuing the goal of total artificial circulation in 1931 after a young female patient died of blocked lung circulation. Gibbon realized that it was necessary to keep oxygenated blood circulating without use of the heart, especially to the brain, to carry out careful operations on the heart under direct vision. His pursuit was to last for almost three decades.

After years of intensive experiment, John Gibbon, his wife, Mary, and others were able to construct a heart-lung machine to allow such artificial circulation. On May 6, 1953, surgery using the heart-lung machine was successfully performed on the first human, 18-year-old Cecilia Bavolek, to close a hole between her upper heart chambers. Gibbon's original heart-lung machine was massive, complicated, and difficult to manage. It damaged blood elements and caused bleeding problems and severe consumption of red blood cells. Because of its ability to permit corrective operations to be performed inside the human heart for the first time, however, these drawbacks of heart-lung bypass were considered acceptable. The era of open heart surgery had begun.

Product Improvements

Gradually, the safety and ease of use of heart-lung equipment improved. With today's state-of-the-art machines, minimal blood trauma occurs during heart-lung procedures. It is now commonplace for surgeons to stop the heart from beating for several hours while the circulation is maintained by heart-lung equipment.

Now that patients can be kept alive during heart surgery, a whole new range of operations has become possible. Congenital heart defects (those occurring at birth) can be repaired. Diseased or damaged heart valves can be replaced. Coronary bypass surgery, in which a replacement blood vessel is used to carry blood flow around a blocked section of artery, is commonplace. Thanks to Gibbon's heart-lung machine, open-heart surgery, especially coronary bypass, has become routine throughout the world.

How It Works

Blue blood withdrawn from the upper chambers of the heart is

siphoned into a reservoir. It is then pumped through an artificial lung to expose it to oxygen. When the blood is passing through the lung (or oxygenator), it comes into close contact with the surfaces of the machine itself. Oxygen gas is delivered to the interface between the blood and the machine, allowing the blood cells to absorb oxygen molecules directly. The blood is now red in color, owing to its rich content of oxygen. The heart-lung machine next pumps the red blood back into the patient through a tube. The heart-lung circuit is a continuous loop: as the red blood goes into the body, blue blood is drained into the pump.

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