What Is Cardiovascular Perfusion?
During open heart surgery, doctors require a bloodless, stationary place to work. To accomplish this, the doctor stops the heart from beating and shunts blood away from it. A heart-lung machine pumps blood through the patient's arteries and draws it back into the machine to be reoxygenated so that the patient's body is supplied with the required amount of blood. When blood is removed and returned by artificial means outside the body, it is called extra-corporeal circulation, or ECC. ECC can be used as a treatment for other failing organs, but when it is used in place of the heart and lungs specifically, it is called cardiovascular perfusion.
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History
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In 1813, Julien Jean Cesar Le Gallois developed the idea of artificial circulation. However, Dr. Jack Gibbon created the precursor of the technique in 1937. In 1953, he used the technique to complete the first successful open heart surgery. In the 1960's, Richard Sarn developed several medical devices, such as the heart-lung machine, which acts as the patient's heart and lungs during ECC.
Cardiovascular Perfusion
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Cardiovascular perfusion is a medical technique that allows heart surgeons to perform open-heart surgery without the patient's heart continuing to beat. A machine acts as the heart during this period of deliberate cardiac arrest. This machine, using tubing made of clear polyvinyl chloride, draws unoxygenated blood from a large vein. The machine oxygenates the blood and then returns it through a large artery.
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Heart-Lung Machines
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Heart-lung machines used in perfusion consist of five pumps. A roller head pump creates suction to draw blood into the machine. The other four provide fluid, gas, and potassium to the patient. Potassium causes the heart to arrest, keeping it motionless during the procedure. In the machine, blood pools in a reservoir and is separated from the outside air by a membrane oxygenator. Oxygen and carbon dioxide cross this barrier to oxygenate the blood. The barrier keeps the blood from clotting. The reoxygenated blood is pumped back into a large artery. Similar machines can also act as kidneys and livers for patients requiring them.
Procedures
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Medical procedures that require use of cardiovascular perfusion include angioplasty--a widening of blood vessels due to occlusion; stent procedures, which place artificial tubing in an occluded artery, and cardiac valve replacement. ECC is also used in treatment of hypothermia. The blood can be removed and warmed in the machine.
Perfusionists
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Perfusionists are not doctors. They are medical technicians. Medical technician schools require a bachelor's degree as a prerequisite for their programs, which last between 12 and 16 months. During surgery, the perfusionist monitors the heart-lung machine and controls the levels of oxygen and carbon dioxide in the patient's blood, and they make sure that the patient's blood continues to be pumped into their veins.
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References
- Photo Credit surgery image by Andrey Rakhmatullin from Fotolia.com
