Features May 2011 Issue

Patients Should Speak Up About What Replacement Heart Valves They Prefer

Research raises questions about whether some heart patients should get mechanical valves instead of bioprosthetic valves, but several factors need to be considered.

When one of your heart valves needs to be replaced, you have two choices: a mechanical valve or a bioprosthetic valve, made from the heart valves of a pig or cow. Several key factors must be considered when making such a decision, and a recent study suggests that the age of the patient may be among the most important factors.

Tissue-engineered heart valves, such as the one pictured above, may not equal the life expectancy of a mechanical heart valve, but they have other advantages that you should discuss with your doctor if a valve replacement is needed.

A study presented at the Society of Thoracic Surgeons annual meeting in February found that younger heart valve patients are more likely to survive 10 years if they have a mechanical valve, as opposed to a bioprosthetic valve. The researchers suggested that the difference was primarily because mechanical valves simply functioned better over time compared to the bioprosthetic valves.

In general, bioprosthetic valves require more re-operations. By their nature, the biological valves will tend to give out sooner than mechanical valves that are made of durable materials such as titanium, Teflon, carbon, polyester and Dacron. A mechanical valve could last indefinitely, while a biological valve may start to give out in 10 to 15 years.

But there are other considerations, along with the possibility of having to have subsequent heart valve surgeries. The biggest issue may be the need for mechanical valve recipients to be on anticoagulant medications for life. The risk of clotting is greater with mechanical valves, so blood-thinning medications, such as warfarin, are prescribed. But warfarin requires frequent monitoring, and over time the costs can add up. Bioprosthetic valves carry a much lower clot risk, so anticoagulant therapy isnít a lifetime requirement for patients getting tissue-based replacement valves.

"Although the guidelines suggest young patients should get mechanical valves and older patients biological valve, patient preference and lifestyle and safety are most important," says Cleveland Clinic cardiac surgeon Marc Gillinov, MD. "If a person has an absolute contraindication to blood thinners, a biological valve is best. Otherwise, more and more people choose biological valves for lifestyle reasons."

Reaching a Decision

The heart contains four main valves and when valve disease is diagnosed, doctors prefer to repair the patientís own valve, rather than replace it. However, if the damage is too great and repair is inevitable, doctor and patient should discuss all the options thoroughly.

"I prefer to let the patient tell me what he or she wants," says Dr. Gillinov. "I review the data. The patient tells me what fits with his or her life."

Currently, about 60 percent of patients who receive an artificial heart valve get a mechanical valve, while the other 40 percent or so get a bioprosthetic valve.

Though some patients may regret their decisions later, Dr. Gillinov says it is rare to change a replacement valve that is working fine, just because the patient changed his mind. "That would be a pretty big deal," Dr. Gillinov says. "I have done it only one time. We went from a mechanical to a tissue valve because the clicking of the mechanical valve was driving the patient to distraction."

Indeed, the sound of a mechanical heart valve opening and closing can, but not always, be heard by the patient and those around him. The noise is certainly among the factors patients must weigh when deciding what kind of replacement valve they want.

Future of Valve Surgery

In addition to determining the type of valve a patient should receive, there are increasing options for how physicians actually replace the valves in the heart. Most heart valve replacements are done with an open chest, though more surgeons are finding that minimally invasive surgeries, done through small incisions are allowing them to perform the same work, but with much less trauma and stress on the patient. Certain types of valve surgeries can be done with robotic surgical tools, though the use of robotic surgery is still in only a few select locations.

"And for biological valves, the big new developments are in percutaneous or catheter-based aortic valve replacement," Dr. Gillinov says. "But this is not yet FDA approved."

He adds that studies are also under way to determine whether patients can avoid anticoagulation therapy with mechanical valves. The studies have not been completed. If itís determined that mechanical valve recipients can avoid taking blood thinners over the long term, a significant risk for those patients could be eliminated.

"The major side effect of anticoagulation is bleeding," Dr. Gillinov says. "If a person is in an accident or develops a bleeding problem, the mechanical valve with its anticoagulation will cause increased risk."