Heart valves keep blood flowing forward within the heart. If one
of them stops working, it may need to be repaired or replaced.
One replacement option is a mechanical valve. These last longer
than biological (tissue covered) valves. But they also tend to
cause small blood clots that can lead to strokes. Thats why
people who get a mechanical heart valve take the blood thinner
warfarin (Coumadin). They need periodic blood tests to make sure
that the amount of blood thinning is just right. Usually blood
tests are done monthly. The blood test is called an INR. It
measures the time it takes for blood to clot. If the INR is too
high (meaning blood is too thin), the warfarin dose is reduced.
Too low, the dose is increased. Changes in diet or medicine can
affect the INR. For some people, INR varies considerably even
without any changes in their daily routine. This means more
frequent blood tests. Unfortunately, there is no good
alternative to warfarin right now. It was hoped that dabigatran
(Pradaxa) would work as we