|2010-11-07 05:03 (UTC)
Interesting question. The valve tissue is made genetically neutral (as well as completely sterile) by the valve manufacturer. I doubt that Boston Scientific, for example (Mark's bovine valve provider), raises cows for the purpose. I also doubt that cows are raised just for heart valves. Seems like a waste of a lot of cow.
I suspect (and it's only a suspicion) that cow valve specifications are known, and hearts purchased as part of the normal slaughter process. Any healthy heart would likely serve.
But that's just a commonsense guess on my part based on what I know of how the tissue is treated before being turned into a bovine valve. Really, there isn't much "cow" left in it. And if you handle one in the doctor's office, you can't hardly tell it ever came from an animal at all.
For example, I was surprised to learn that it's one size fits all in valve-land. Mark's bovine valve is larger than the old valve he had. His heart stretched to accommodate, and it's just not a problem. We are flexible. Surprised the heck out of me. I thought it'd be at least small, medium, large. But nope.
But if you learn differently (like, bovine valves come from guernseys with blue eyes) I think that'd be fascinating to know.