Deciding Between a Tissue and a Mechanical Valve

Overview

By John V. Conte, MD

Article

If you have heart valve disease and find out that you need valve replacement surgery, one of the biggest decisions you may face is what type of valve to get. This decision has never been more complicated. Why? Because there are a lot of valve replacement options and many approaches to performing the valve replacement.

Surgical valve replacement can be performed through the front of the chest (by completely or partially dividing the breastbone) or from the side (by going between the ribs and not dividing any bones). The actual technique of implanting the valve is the same, regardless of the approach or the valve selected. The issue you have the most control over is the type of valve you receive.

Just like cars, there are many makes and models of valves. In general, the types of valves can be divided into two categories: tissue valves and mechanical valves, each with its own unique characteristics.

Valve Types and Characteristics

Tissue valves, also called biological or bioprosthetic valves, are made from animal tissue. The tissue may be bovine (cow) or porcine (pig) and constructed from the pericardium (the protective sac that surrounds the heart) or heart valve leaflet tissue. Both types of tissue valves work well and have similar defining characteristics. Tissue valves do not require lifelong blood thinners, such as warfarin (Coumadin) or some of the newer medicines, like apixaban (Eliquis). The disadvantage of tissue valves is that they wear out after about 12 to 15 years.

Mechanical valves are made from different types of metal and generally do not wear out, though patients will be required to take blood thinners for life. If the blood thinners are not taken properly, blood clots may form and potentially lead to strokes or prevent the valves from functioning properly.

Neither mechanical nor tissue valves have been definitively associated with longer survival or fewer complications. Age is one of the most important factors when making the decision between a mechanical and tissue valve. In general, patients older than age 65 tend to receive tissue valves, while patients under age 60 tend to receive mechanical valves. However, valve durability and individual patient survival are both unpredictable.

In addition to valve durability, other factors to consider include the use of blood thinners and noise. If you need blood thinners for medical reasons (such as blood clots), then a mechanical valve may make sense. On the other hand, if you have a condition that prevents the use of blood thinners, such as gastrointestinal bleeding or conditions that are associated with easy or frequent bleeding, you may prefer a tissue valve. Lifestyles choices, including playing contact sports, planning to have children, or having a job that prohibits blood thinners (i.e., active duty military) may result in your doctor recommending a tissue valve.

It’s also important to note that mechanical heart valves make noise. Some patients don’t hear the noise, some like it, some don’t care, and others don’t like the sound. It’s a personal preference, but definitely worth considering.

Long-Term Considerations

In your deliberations, you should think about how long the tissue valve will last and what to do when it wears out. The valve can be replaced, but that involves another heart operation. Other issues that may cause tissue valves to wear out sooner than expected include renal failure requiring dialysis, high blood pressure, and small valve size, as well as high lipids and cholesterol.

The recently availability of transcatheter valves is playing a large role in the decision-making process. Transcatheter valves are placed without open surgery and, in most cases, with a catheter through an artery in the groin. Patients who are at high and intermediate risk for traditional surgery may be candidates for transcatheter aortic valve replacement (TAVR).

For patients with failed or worn out tissue valves, a cardiothoracic surgeon can perform TAVR to insert a new valve inside the failed tissue valve without another major operation. The key is for the initial valve to be large enough so that the new “valve in valve” won’t be too tight and restrict blood flow (stenotic). Because TAVR is relatively new, it’s too soon to know the long-term durability of these transcatheter valves.

If you are considering valve replacement surgery, do your homework and talk with your doctor to determine the right choice for you.

 

The opinions expressed in this article are those of the author and do not necessarily reflect the views of The Society of Thoracic Surgeons.