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Heart Valve Replacement – Half a Century of Medical Innovation
Medically reviewed by Dr. Michael Carmichael
Success, A Blend of Skilled Surgeons & Technological Developments. In 2014, a person with a faulty heart valve can have it replaced and expect extraordinarily low operative mortality rates and minimal complications. Today’s positive reality represents decades of research and refined surgical skills. 1960s - MECHANICAL VALVES. The first aortic valve replacement occurred in 1960, using a mechanical valve that was essentially a ball loosely fit inside a ring. It was soon replaced by a valve using a disk that tilted open and closed. Eventually, a valve was developed with two leaflets. Leaf versions of the mechanical valve can last a long time but the patient must take medication to prevent blood from thickening and clotting the valve opening.
LATE 1960s – HUMAN-to-HUMAN TRANSPLANT
One popular technique involved taking a donor individual’s valve to replace the patients. Another technique took the patient’s pulmonary valve to replace their aortic valve; then, replace the pulmonary valve with one made from the patient’s tissue, a doubly complicated approach.
1970s – COW & PIG TISSUE VALVES
In the 1970s, surgeons were experimenting with using valves that were stamped out of the sack surrounding the cow’s heart or using a valve from a pig. New anti calcification treatment makes the cow the tissue valve of choice, lasting twice as long as the pig valve. Patients with the tissue valves don’t need to take anti-blood clotting drugs.
“About 20 years ago, the majority of valves I implanted were mechanical,” said McLeod Heart Surgeon Dr. Michael Carmichael. “Now, tissue valves are the vast majority I implant, probably by a 20-to-1 ratio. Since I turned 55, I’ve told my patients that – if it were me – I would choose a tissue valve and hope to get 20-30 years out of it.”
What happens if or when a replacement valve wears out?
“I replaced a valve in a 29-year-old racecar driver,” says Dr. Carmichael. “In 15-20 years, we replaced it again. And then in time, we did a third replacement.”
21st CENTURY - TAVR
One of the newest developments is a minimally invasive procedure that inserts a pre-fabricated valve – folded up much like a collapsed umbrella – into the faulty valve opening. Then the insert is opened – pushing the faulty valve out of the way and creating a cleaning opening with a new valve. This procedure is called the Transaortic Valve Implantation (TAVI) or Transaortic Valve Replacement (TAVR). It offers hope for patients who otherwise might not medically be able to undergo surgery
While very promising as a minimally invasive technique, it will take years before the evidence tells us how long TAVI/TAVR valves will last.
Sources include: McLeod Health, National Institutes of Health, American Heart Association Journal, European Heart Journal, Drexel University, Journal of the American College of Cardiology