|MadSci Network: Medicine|
Hearts are harvested from the pigs at the slaughter house. The hearts are sent to a laboratory which processes the pig heart valves so they can be used for human heart valve replacement. The lab dissects the aortic valve from the pig hearts (the aortic valve is one of the four valves found in the heart of a mammal). After some delicate dissection to remove excess tissue, the pig valves are then preserved in a solution similar to formaldehyde. This makes them unrecognizable to the human body as foreign tissue, which means they will not be rejected by the immune system of the person receiving one of them. Being preserved also means that the pig valve tissue is not alive when it is placed in the human heart. Heart valves don't have to be made of live tissue since they work by passively responding to blood pressure differentials within the chambers of the heart.
Each preserved valve is sutured into a ring of synthetic material. Natural material would be rejected by the immune system of the person receiving the valve. Smaller pig valves are sutured into small rings and larger pig valves are sutured into large rings. When the replacement surgery is performed, many different sizes of pig valves are available to the surgeon. The surgeon determines which size pig valve will be used for the replacement.
Pig valves are used because their hearts are anatomically and physiologically similar to human hearts. Pigs are also plentiful, so there is virtually an unlimited supply of valves.
Some of us have probably eaten the meat from a pig whose heart valve has saved or improved the quality of another person's life!
Go to: http://www.heartsurgeons.com/valvedesign.htm for more information.
I hope your co-worker is doing well.
Robert Houska, Mad Scientist
Try the links in the MadSci Library for more information on Medicine.