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.