Heart Health Cardiovascular Procedures

Tissue Versus Metal Valves: Weighing The Factors

Artificial valves were first used in heart valve replacement surgery over 30 years ago. The success of this surgery has legitimized replacement of diseased and/or damaged heart valves with artificial valves as a routine surgical procedure. Approximately 150,000 valves are replaced worldwide each year. While the demand for artificial valves in Europe and the United States has stabilized, world demand for these prostheses is increasing at the rate of about 10 percent per year.

There are two main types of artificial heart valves available: mechanical (metal) and tissue (pig) valves. However, there is frequently no consensus pertaining to the issue of the ideal type of valve device for most patients. The decision should be based on a thorough discussion between the surgeon and patient. Ideally, the patient should make the final decision. The purpose of this article is to provide an overview of the risks and benefits of these two types of valves, as well as indications for a preferred type of artificial valve in different patient groups.

Mechanical Valves
Mechanical artificial heart valves were first introduced in 1960. In general, the mechanical valve is made of some metallic alloy.

The benefits
The main advantage of this type of artificial heart valve is its excellent lifetime durability. Theoretically, the valve can last forever. In other words, if you have a mechanical valve, it is unlikely that you will require another surgery on the same valve. Avoiding another operation is very appealing to many, especially those that are young.

The drawbacks
However, the major drawback is the need for long-term anticoagulation with a "blood thinner". This medication goes by different names but the most common one is coumadin, which is a potent blood thinner and requires careful monitoring by a physician. Aspirin is also a blood thinner but it is not potent enough for mechanical heart valves. Taking a blood thinner is necessary to prevent the formation of blood clots on the valve. These blood clots can break off and cause a variety of problems such as a stroke and malfunction of the heart valve. As a result, a blood thinner is an absolute requirement after placement of an artificial mechanical valve.

But taking a blood thinner has its own complications. The major problem is a risk of bleeding. Studies have reported that the rate of anticoagulation-related bleeding complications in patients with mechanical valves is as high as 30-40% over 10 years versus 10-20% for patients with tissue valves. A bleeding complication can be minor, such as bleeding from a superficial cut, but it also could be major, such as bleeding in the brain or in the gastrointestinal tract.

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