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 Arokiasamy underwent replacement of his mitral valve with a
mechanical valve and remained well on medications. During one of
his business trips, he forgot to carry the medicines and could
not take them for a week. However, he remained without problems
and that prompted him to go off drugs altogether. Six months
later, he was admitted with stroke and his right half of the
body was functionless.
What is meant by coagulation of blood?
It is a normal phenomenon in our body by which the bleeding is
arrested. There are a set of blood cells called platelets. They
stick on to the site of bleeding and form a temporary plug.
There are special proteins in the blood called ‘coagulant
factors’ which form dense clot over the plug formed by
platelets. The heart, arteries and veins in the body have a
smooth lining of cells which prevent abnormal clotting of blood.
However, if blood encounters a rough surface or an abnormal
surface like an artificial valve, it tends to form clot over
those structures.
Why are the blood clots harmful?
When blood clots form in abnormal places,
they cause reduction in blood flow. The tissue suffers from lack
of oxygen and nutrients and dies. If the clot blocks an artery
in the brain, it causes stroke. If it blocks the artery to
kidney, it will result in kidney failure. A large clot in the
lungs can cause sudden death.
What are blood thinners?
These are the medicines that make the blood
less likely to form clot. They do not ‘thin’ the blood, i.e.
they do not decrease the viscosity of blood. Hence it is a
misnomer.
What are the types of blood thinners?
Medicines are available to suppress the
action of platelets, called as antiplatelets. Two drugs commonly
used for this purpose are aspirin and clopidogrel. Another group
of medicines suppress the action of clotting factors and are
called anticoagulants. Heparin is used intravenously for short
term or when a rapid effect is needed. For long term use, the
most commonly used drug is coumadin commercially available as
Warfarin.
Who should take these drugs?
Antiplatelets are given for a variety of
indications, most commonly to prevent heart attack and stroke.
Long term oral anticoagulants are given for one of the following
reasons:
Prosthetic heart valve
Blood clots in the veins/lungs/heart
Abnormal heart rhythm that can induce blood clots to form
Dilated and poorly pumping heart
What is the importance of strictly
following the drug dose and schedule?
If the drug is not taken in adequate dose, it
would be of no use and abnormal clots would form. If the dose is
higher than expected, it can result in abnormal bleeding. The
effect of the drug varies depending on the food intake, intake
of other drugs, diarrheal illnesses, liver disease, etc. Hence,
the dose of anticoagulants needs to be adjusted frequently
unlike most of the other medicines.
How do we monitor the oral anticoagulant
therapy?
A blood test (Prothrombin time) is done every
month to assess the level of anticoagulation. The result is
expressed as international normalized ratio, shortly called as
INR. The level of INR is based on the indication for which the
anticoagulation was started. For example, those with artificial
valves should have the value of INR between 2.5 and 3.5. If the
value is lesser, the patient runs the risk of abnormal clot
formation. If the value is much higher, then he runs the risk of
bleeding.
This test has to be done only in standardized
labs and preferably to be done in the same lab every time. One
could land up in serious trouble if this monitoring is not done.
The cost of doing this test is much less than what one would
spend to treat the complications resulting form not doing it.
What are the precautions one should take
while on this therapy?
There should be no drastic change in the
dietary pattern. Binge eating and drinking should be avoided. If
there is a change in the dose of another concomitant medicine, a
recheck of INR should be done after 4-5 days. Even simple
antibiotics like erythromycin alter the effect of oral
anticoagulants. Hence self medication could be dangerous. Herbal
medicines and other unconventional drugs should be absolutely
avoided. For obvious reasons, one should avoid contact sports
while on this medicine.
Arokiasamy was found to have a clot blocking
a major artery of the brain. There was a big clot on his
artificial valve preventing it from functioning normally. He was
actively managed with drugs to dissolve the clot and
anticoagulation was reintroduced. Luckily, he survived the
problem. However, he was left with poorly functioning right hand
and leg.
Kannan BRJ
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