(This picture was taken during my visit to Paris in 1999)

Sir Magdi Yacoub

Choices of Prosthetic (Replacement) Valves

Once again, there are two basic options:  Either mechanical (metal) or biologic (tissue).

So, how do you choose between the various choices of mechanical and biological valves?

The advantages of mechanical valves:

Mechanical valves (metal valves) are easy to insert generally speaking they last forever.  Mechanical failures are extremely rare.  They are not rejected by the body, so no special anti-rejection medications are needed.

The disadvantages of mechanical valves:

Mechanical valves require the patient to take Coumadin® (a blood thinner) every day, or else the valve will develop clot that can lead to catastrophic mechanical failure and/or stroke from emboli to the brain.

Coumadin® (warfarin sodium) is a safe drug, but it has risks.  Statistically, there is a 2.2% chance per year of bleeding complications and a 1.8% chance per year of clotting complications.  You can have bleeding complications despite having the drug level monitored closely.  Clotting can occur if the blood levels drop for some reason and it is not picked up in time.

Most of all, taking Coumadin® every day is inconvenient for the patient.  You have to watch what you eat since certain foods reduce the anti-coagulation affect in your blood.  Also, you will need regular blood tests, sometimes weekly, to adjust your blood levels.

Finally, mechanical valves often make a clicking sound that can be heard by the patient or by someone standing near the patient, particularly in thin people.  This can be annoying to the patient and somewhat embarrassing.  I tell the patients to call me if the clicking stops! ☺

The advantage of tissue valves:

Tissue valves do not require blood thinners, except maybe a daily baby aspirin.  There is no need for Coumadin®, though some surgeons will place their patients on Coumadin® for 8 weeks after the surgery until the tissues are healed.  Long-term, a daily aspirin will suffice.  Therefore, the risks and inconvenience of long-term anti-coagulation is avoided.

It may surprise you to know that tissue valves are not rejected by the body either and therefore do not require any anti-rejection medication, even the human valve (homograft/cadaver valve).

Also, tissue valves are silent.  They don't make any noise when they open and close.

The disadvantage of tissue valves:

Tissue valves (pig, cow, or human) are slightly more challenging to insert, particularly transplanting another human valve (homograft/cadaver valve).  However, an experienced surgeon should have not difficulty with any of these tissue valves.  Indeed, greater than 90% of the valves I use to replaced diseased valves are tissue valves.

Tissue valves do not last forever.  Interestingly, the longevity of a tissue valve depends in part on the patient's age.  Young patients will develop calcium deposits more quickly on tissue valves than older patients.  For example, a pig or cow valve placed in a 35 year old patient will probably last no more than 10 years.  That same valve place in a 75 year old patient will most likely last 15 or more years, which would be fine for someone that age.

As far as tissue valves go, the human valve and some of the newer chemically treated pig valves may last the longest, but this is debated in the literature.

My Recommendations

I look at each patient differently, though my bias is toward tissue valves.  The reason I generally prefer tissue valves is because I am concerned about the long-term risks of Coumadin®.

Age is an important factor, as I eluded to above.  For patients over 70 years of age, particularly if they have associated medical problems such as coronary artery disease, I will always recommend a tissue valve to replace a diseased aortic valve.

For younger patients, I try to assess the patient's lifestyle and the patient's concerns.  I try to explain the balance between the risk of long-term anti-coagulation required with a mechanical valve versus the risk of a second operation with a tissue valve.  It's always interesting to me how each patient is different.  Most of the times, the patient will make the decision on their own.

After I get done explaining all of the valve options, I let the patient think about it for a while and discuss the matter with their family.  Though I give my advice, I often recite to them the line from Fox Cable News: "We report, you decide!"

Don't get me wrong, mechanical valves are an excellent choice in select situations.  For example, it is my valve of choice in a young patient with mitral valve disease that cannot be fixed by repairing the valve.  There are also times when a mechanical valve is the best choice for the aortic position, too.

Fortunately, I have a large experience placing all the variety of valves available, so that I can honestly pick the right valve for the right patient.  Some surgeons only feel comfortable placing certain types of valves.  Ask your surgeon what the other choices are for valve replacement and inquire as to your surgeon's experience placing all of the different valves.