Should I replace my aortic valve with a mechanical or tissue valve?

Introduction

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This information will help you understand your choices, whether you share in the decision-making process or rely on your doctor's recommendation.

Key points in making your decision

Once you and your doctor have decided on valve replacement surgery to treat your aortic valve stenosis, you must choose between two types of valves: mechanical or tissue (also called biological). Mechanical valves are made of metal, carbon, or artificial materials, and sometimes a combination of these. Tissue valves are taken from the heart of a pig or a cow. Tissue valves may also be preserved human valves taken from a donor, similar to a donated organ.

Consider the following when making your decision:

• The main trade-off between mechanical and tissue valves is durability versus risk of blood clots. A mechanical valve will last 20 to 30 years, while a tissue valve will last about 10 to 15 years. However, the risk of blood clotting is higher with a mechanical valve. Blood clots can cause a heart attack or stroke.
• If you are 60 or younger, a mechanical valve is likely to be your best choice because you are young enough that you probably would outlive a tissue valve. It also may work better because tissue valves can become hardened, or calcified, in younger people.
• If you were born with a bicuspid aortic valve (with two valve leaflets instead of three), a mechanical valve will be a better choice because you will likely need to have the valve replaced when you are young.
• If you choose a mechanical valve, you will have to take a blood-thinning medicine (anticoagulant) every day for the rest of your life to lower your risk of blood clots. If you choose a tissue valve, you will need to take anticoagulants for only a few months after surgery.
• People who are already taking anticoagulants for other conditions, such as an irregular heartbeat (arrhythmia), also should strongly consider a mechanical valve. The only real advantage of a tissue valve is not having to take anticoagulants, so someone who is already taking the medicine would likely not get any added benefit from a tissue valve.

Medical Information

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What is aortic valve stenosis?

Aortic valve stenosis is a narrowing of the aortic valve. The aortic valve allows blood to flow from the heart's lower left chamber (ventricle) into the aorta. Stenosis prevents the valve from opening properly, forcing the heart to work harder to pump blood through the valve. This causes pressure to build up in the left ventricle and thickens the heart muscle. The heart can compensate for aortic valve stenosis and the resulting pressure overload for a long time. Eventually, however, the heart will not be able to maintain the extra effort needed to pump blood through the narrowed valve, resulting in heart failure.

Is valve replacement surgery the only treatment for aortic valve stenosis?

Once you develop symptoms of aortic valve stenosis, surgery to replace the aortic valve is the only effective treatment. Symptoms include chest pain, fainting, lightheadedness, shortness of breath, and heart palpitations. Your doctor may prescribe medicines to treat your symptoms, but once the valve is damaged, it needs to be replaced.

Heart failure will develop fairly quickly if you have symptoms of severe stenosis and do not replace the valve. Without a new valve, the life expectancy of a person who has symptoms of severe aortic stenosis is 3 to 5 years.¹

What are the differences between mechanical and tissue valves?

You and your doctor will need to weigh the shorter durability of a tissue valve, which increases the likelihood that you will need another replacement valve, against the drawbacks of taking anticoagulant medicine for the rest of your life or as long as you have a mechanical valve. These medicines can increase the risk of bleeding.

Mechanical valves last at least 20 to 30 years in most cases. The greater durability of a mechanical valve makes it less likely that you will have to replace the valve in your lifetime. While mechanical valves can break down, this is very rare.

In spite of chemical treatments to improve durability, tissue valves typically last about 10 to 15 years. They usually fail because of the same calcification process that affected the original valve. Tissue valves may also tear or become infected. When tissue valves are used, a second valve replacement may be necessary.

In general, mechanical valves are the preferred choice for children, teens, and adults age 60 and younger, all of whom will likely outlive a tissue valve and need another valve replacement.

Tissue valves are most appropriate for people who are less likely to outlive their valves, which includes people who:

• Are older than 65.
• Are younger than 60 and have lung disease.
• Have heart failure.
• Have coronary artery disease.
• Have kidney disease.
• Have a life expectancy of less than 10 years.

Because anticoagulant medicine is needed for only a short period after surgery, a tissue valve may also be the best choice:

• When the risks of bleeding associated with anticoagulants are too great.
• If you do not want to limit your activities because of the risks of bleeding associated with anticoagulants.
• If you don't want to take anticoagulants.

Why is blood clotting more likely with a mechanical valve?

Because your body recognizes a mechanical valve as artificial, your blood has a tendency to clot on the surface of the valve. The valve components are also hard, unlike the soft tissue of a natural valve, and can tear blood cells as they pass through the valve, causing clots to form. To prevent blood clots, people who receive mechanical valves must take anticoagulants, such as warfarin (for example, Coumadin), for the rest of their lives. This medicine can increase the risk of severe bleeding from an injury and can cause a number of side effects.

Tissue valves cause a much lower risk of blood clotting than mechanical valves. It is generally necessary to take blood-thinning medicine for only several weeks after valve replacement, and after that you would take only aspirin. While there is a risk of complications associated with tissue valve failure or infection, these complications are relatively rare.

If you need more information, see the topic Aortic Valve Stenosis.

Your Information

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Your choices are:

• Get a mechanical replacement valve.
• Get a tissue replacement valve.

The decision about whether to get a mechanical or tissue valve takes into account your personal feelings and the medical facts.

Deciding about a mechanical valve or tissue valve

Reasons to get a mechanical valve

Reasons to get a tissue valve

A mechanical valve lasts 20 to 30 years. The durability of a mechanical valve makes it less likely that you will need another replacement valve in your lifetime. You are younger than 60 and are likely to outlive a tissue valve and require another valve replacement. You already are taking anticoagulants for another condition. Are there other reasons you might want to get a mechanical replacement valve?

You are older than 65 or have a health problem that makes it unlikely that you will outlive a tissue valve. You are less likely to develop blood clots. You do not want to take anticoagulants permanently. You are worried about the increased risks of bleeding associated with anticoagulants. Tissue valves tend to last longer in older people. Are there other reasons you might want to get a tissue valve?

These personal stories may help you make your decision.

Wise Health Decision

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Use this worksheet to help you make your decision. After completing it, you should have a better idea of how you feel about choosing a mechanical or tissue replacement aortic valve. Discuss the worksheet with your doctor.

Circle the answer that best applies to you.

I am young enough that I would likely outlive a tissue valve.	Yes	No	Unsure
I am older than 65 and will not likely outlive a tissue valve.	Yes	No	Unsure
I am already taking anticoagulants for another condition, so a mechanical valve is a better choice.	Yes	No	Unsure
I am concerned about the increased risk of blood clotting with a mechanical valve.	Yes	No	Unsure
I am concerned about the risks of bleeding associated with anticoagulants and therefore feel that a tissue valve is a better choice.	Yes	No	Unsure

Use the following space to list any other important concerns you have about this decision.

What is your overall impression?

Your answers in the above worksheet are meant to give you a general idea of where you stand on this decision. You may have one overriding reason to choose a mechanical or tissue valve.

Check the box below that represents your overall impression about your decision.

Leaning toward a mechanical replacement valve

Leaning toward a tissue replacement valve

Return to the topic Aortic Valve Stenosis.

References

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Citations

1. Bonow RO, Braunwald E (2004). Aortic stenosis section of Valvular heart disease. In E Braunwald et al., eds., Heart Disease, 7th ed., vol. 2, pp. 1582–1592. Philadelphia: Saunders.

Credits

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Author	Robin Parks, MS
Editor	Kathleen M. Ariss, MS
Associate Editor	Pat Truman
Primary Medical Reviewer	E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer	George Philippides, MD - Cardiology
Last Updated	November 17, 2005