Aortic Valve Replacement

Aortic mechanical valves (sometimes inaccurately referred to as "metal" valves) are made from biocompatible materials such as titanium or pyrolytic carbon and offer long-term durability that can last a lifetime. The first bileaflet mechanical heart valves were implanted in 1977. Since then, technology and design advancements to mechanical heart valves have made them an extremely reliable, safe and effective alternative for patients.

The most commonly used mechanical heart valve is the “bileaflet” valve with two semicircular leaflets that open to allow blood to flow freely in one direction and close to prevent regurgitation (flow of blood back through valve).

Mechanical Valves, Advantages and Disadvantages

Durability: Mechanical heart valves provide excellent long-term durability, decreasing the need for replacement surgeries. Mechanical valves are a good choice for younger patients, particularly children and adolescents who are prone to higher failure rates with tissue valves.

Anticoagulation: Long-term anticoagulation therapy is needed with mechanical valves. Mechanical valves should not be prescribed for women who are pregnant or plan on getting pregnant and cannot take anticoagulants (blood thinners).  Oral anticoagulant therapy has been used for half a century and are efficient in preventing or delaying the clotting of blood.¹ Coumadin®, the most common of these drugs, is listed as one of the 20 most frequently prescribed drugs in the United States

Aortic Tissue Valves

Aortic tissue valves – also called biological or bioprosthetic valves – are most often made from animal tissue and consist of:

• Porcine tissue (pig’s aortic valve)
• Bovine tissue (cow pericardium)
• Equine tissue (horse pericardium)

Aortic tissue valves can also be made from human tissue:

• Donated heart valves (homograft or allograft)
• Patient’s own pulmonary valve tissue (autograft)

Most tissue valves also include some artificial components to provide support and facilitate placement.  Most tissue valves are chemically treated to enhance their durability after implant. The most commonly used tissue valve designs for aortic valve replacements are:

• Stentless Tissue Valves: A stentless tissue valve can be an actual heart valve from either a human donor (homograft) or a pig incorporating the natural leaflets from the original heart valve. Stentless valves are also made from animal tissue – bovine tissue (cow pericardium) or equine tissue (horse pericardium).
• Stented Tissue Valves: Tissue valves that are mounted on a frame (stent) to facilitate positioning and suturing the valve into place.

Tissue Valves, Advantages and Disadvantages

Anticoagulation: Long-term anticoagulant use is generally not necessary with tissue valves, unless otherwise indicated. This is an important consideration for people unable to manage or tolerate anticoagulation therapy and for women who are pregnant or plan on getting pregnant and cannot take anticoagulants.

Durability: Long-term durability is not as good as with mechanical valves. Tissue valves may need replacement every 10-15 years or sooner, particularly in younger patients as deterioration can occur more quickly in children, young adults and middle-aged adults and may become calcified, infected, or torn. As a result, tissue valves are often prescribed for patients who are between the ages of 55-70 years or have a life expectancy of fewer than 10 years.²

1. www.ncbi.nlm.nih.gov/pmc/articles/PMC2000654/
2. www.sts.org

Coumadin is a registered trademark of Bristol-Myers Squibb.