NO LIFETIME GUARANTEE A person's heart generally beats 80 million times per year and five to six billion times over the course of a normal lifetime, according to Irvine, Calif.-based valve producer Edwards Lifesciences. Often, the heart's valves do not last a lifetime.
Image: © EDWARDS LIFESCIENCES
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The heart relies on four valves that act as one-way gates, controlling blood flow out of each of the heart's four chambers. The mitral valve between the two left chambers of the heart has two leaflets, or cusps; the tricuspid, pulmonary and aortic valves each have three. The leaflets swing open and shut like saloon doors with every beat, maintaining a steady blood supply. (A person's heart generally beats 80 million times a year and five to six billion times over the course of a normal lifetime, according to Irvine, Calif.–based valve producer Edwards Lifesciences.)
Slide Show: Artificial heart valve improvements over the past 50 years
As comedian and actor Robin Williams, 57, and 83-year-old former first lady Barbara Bush found out recently, in many cases, the valves don't last a lifetime; some become leaky. Called a regurgitating valve, this allows pumped blood to wash back into the heart. Others pick up calcium from the blood, eventually becoming hardened, restricting blood flow (a condition known as stenosis). When the body does not receive enough blood, a person can experience symptoms such as shortness of breath. Aortic and mitral valves most commonly require treatment. Once symptoms such as lightheadedness and blackouts arise, a person with an untreated faulty aortic valve has a 50 percent chance of dying within six months, says Eugene Grossi, a professor of cardiothoracic surgery at New York University School of Medicine and director of cardiac surgery research.
That means that for thousands of Americans, an artificial heart valve fashioned from tissue-thin flaps is all that stands between health and heart failure. About 140,000 Americans go under the knife for valve replacement or repair every year, according to Toronto-based Millennium Research Group, a firm that tracks the medical device, pharmaceutical and biotechnology industries.
Doctors have developed several stand-ins for the natural tissue that can regulate blood flow without missing a beat. "Heart valves are the one device that when you get it in and it's successful, you add 10 or 15 years to their life," says Donald Bobo, vice president for heart valve therapy at Edwards Lifesciences. Edwards—along with Saint Jude Medical in Saint Paul, Minn., and Minneapolis-based Medtronic, Inc.—is a top provider of artificial valves worldwide, Bobo says. Sorin Group in Milan, Italy, also has a share in the global heart valve therapy market, estimated to be worth $1.6 billion in 2008, according to Edwards market estimates.
Valve technology took off in 1958 when engineer and Edwards founder Miles "Lowell" Edwards applied his experience designing hydraulic debarking methods for the lumber industry and a fuel-injection system for World War II aircraft to the medical arena. Working with cardiothoracic surgeon Albert Starr, the two developed a valve that Starr could use in his ailing patients. Surgeons implanted the Starr-Edwards artificial valve, designed in Edward's backyard workshop, for the first time in 1960. Although that first patient died shortly after receiving the device, the second survived for 10 more years before dying from a fall off a ladder.
People tried dozens of different designs in the ensuing decades, says Ajit Yoganathan, a biomedical engineer who studies valves at the Georgia Institute of Technology in Atlanta. "Most of them were developed in someone's garage or someone's basement." The technology has evolved from a caged-ball design into valves with artificial flaps, pig valves processed for human use, and hand-sewn biologic valves made from cow tissue.
"All of these valves have analogues in hydraulics, pipelines, aviation, automobiles," Bobo says. But the human body presents special challenges. "Blood ends up being a pretty different environment compared to oil or gas," he adds. The lipids in blood can destroy synthetic materials; tissue valves are subject to the same wear and tear and calcification that natural valves are.
"There is still room for improvement," such as better materials, Yoganathan says. He would also like to see small valves available to children with congenital heart defects. The next development likely to hit the U.S. market is valves that can be implanted without open heart surgery.
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13 Comments
Add CommentI've got a bicuspid Aortic valve that will need replaced give mre some details!
Reply | Report Abuse | Link to thisI have a bicuspid aortic valve that will need replaced. Give me some details!
Reply | Report Abuse | Link to thisWow you have to admit that is pretty amazing!
Reply | Report Abuse | Link to thisRT
www.anonymity.es.tc
I had my aortic valve replaced two months ago, with the valve pictured in slide 6. It is an Edwards bovine tissue valve, model 3000TFX. I am going cross country skiing for a short run tomorrow. This or the mechanical valve are the two main choices out there.
Reply | Report Abuse | Link to thisMechanical lasts basically forever, but you are on blood thinners permanently, so risk of stroke is higher.
The Edwards Bovine tissue does not require thinners, except for a short time after surgery, but does not last as long. Newest reports on longevity are encouraging. I suggest you check out the Cleveland Clinic website. It is the premier heart surgery hospital in the country, and has tons of good information.
It is also possible that your valve can be repaired rather than replaced at Cleveland or one of the other top heart centers. This option is the preferred one if it can be done.
Good Luck.
To tell you the truth I don`t know a lot about that, however my uncle did an operation to introduce an aortic valve, but it requires a blood thinner. Anyway, he is much better know and he looks more young.
Reply | Report Abuse | Link to thisDo you think that nanotubes can be used as aortic valves?
The downside to valve replacement surgery is the time it takes to perform the task, anywhere from 2-5 hours depending on complications. During this period you are kept alive artificially whist the heart is worked on. Setting aside the obvious problems that might occur with the heart, the brain, because of the change in support will begin to 'die', losing cells at a phenomenal rate and the longer your surgery takes the more cells you will lose and this is serious.
Reply | Report Abuse | Link to thisHence, minimally invasive surgery would be a major step forward not just because of the question of brain damage but also the, for many, recovery time would be improved drastically.
I'm certain that video surgery involving robots has already been successfully carried out in the repair of valves and no doubt, this area of telesurgery will advance exponentially.
I SAW MYT VALES IN ACTION WITH ONE VALVE CUSPING TIGHTLY CLOSED FORMED INTO A NICELY FORMED PIRAMID CONFIGURATION BUT THE OTHER VALVE ALTHOUGH IT DID NOT LEAK WAS MUCH MORE FLAT. tHIS CAUSED ME TO THINK THAT THE MORE FLAT CONFIGURED VALVE WILL EVENTUALLY BEGIN TO LEAK; OR PERHAPS THE SAID CONFIGURATIONS OF THESE TWO HEART VALVES ARE NORMAL AND EACH ONE WILL LAST AS LONG WITHOUT LEAKING EXCEPT PERHAPS IN A HIGHTLY TRAUMATIC IMPACT OR DISEASED EVENT.
Reply | Report Abuse | Link to thisNegative that being on blood thinners increases the risks of strokes! Absolute myth!
Reply | Report Abuse | Link to thisI have double-valve mechanical valves in the aortic & mitral position since 1975 & have been on anticoagulatants (blood thinner) for 34 years & have never had a stroke because of it. I have also live a very active life, participating in sports etc., without any complications due to coumadin.
Taking coumadin and having the probability having a stroke is all depends on:
Reply | Report Abuse | Link to this1. Diet, specially Vitamin K
2. Irregular taking coumadin dosage
3. or stop taking coumadin...
4. and wheather ...
A friend stopped taking coumadin, and later a month had a stroke causing disable to talk!
I also have mechanical aortic and mitral valve's. I've had them since 1993 and have been taking warfarin since then with no strokes. I thought I was a one of a kind suprised to see that someone else had something similar since the 70's that's good to know. btw i like hiking (not gonna win any races) and really enjoy snowboarding as well. Had four open heart surgeries from age 2 to age 11. 3 at UCSF and one at UCLA
Reply | Report Abuse | Link to thisHeart valve surgery is used to repair or replace diseased heart valves. The blood that flows between the various chambers of your heart has to flow through a heart valve. The blood flowing from his heart in the large arteries should undergo a heart valve. These valves open enough so that blood can flow through. They then close, keeping blood from flowing backward. There are four valves in your heart: Aortic, The mitral valve, The tricuspid valve, Pulmonary Valve.
Reply | Report Abuse | Link to thishttp://www.insideheart.com/aortic-valve-replacement.html
How is <a href="http://WWW.CAPITOL-HOMECARE.COM">home care</a> affected with patients with artificial heart valves? Do you only need to worry about their cepera or is there any other things we need to watch with an artificial valve?
Reply | Report Abuse | Link to thishow can affect weather my health if i take comadin?
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