Let’s say somebody is getting a heart transplant, how do they keep the blood circulating in the body and spilling everywhere?
During the operation they are connected to a heart-lung machine. This is a machine takes over the function of pumping the blood around the whole body and oxygenating it. This allows the surgeons to remove the patient’s diseased heart and replace it with the healthy donor heart.
While true artificial hearts have only become available in recent years, people have been performing surgery with a device called a heart-lung machine since the 1960s, and research into the idea had been going on for almost a hundred years before that. Heart-lung machines aren’t really practical replacements for the heart on a long-term basis, partly because they’re too big to place inside the body and partly because the blood gets exposed to air, so you need special drugs to prevent it from clotting. But they can do the job long enough to perform heart surgery, and that’s all most people really need them for.
Turns out modern technology has come up with pumps that can circulate blood without using the heart. In fact they made “heart lung machines” which can actually oxygenate the blood as well, replicating the function of the lungs for a while. They would tap into major arteries and veins on either side of the heart to intercept the blood before operating on the heart itself.