Anticoagulation therapy is used to prevent clot formation. They do not lyse clots but they prevent new clots from forming. Since warfarin takes time to act, heparin and warfarin are usually started together in a patient. Once the effect of warfarin is achieved, heparin is discontinued and the patient is continued on warfarin.
Anticoagulants are used in the following conditions: Deep vein thrombosis, and pulmonary and cerebral embolism
Some conditions like being unable to move for a long time predispose a patient to develop clots in the deep veins of the legs. This condition is called deep vein thrombosis. If a part of the clot gets dislodged, it forms an embolus and travels through the blood vessels to different organs. In the lungs it could lead to a fatal condition called pulmonary embolism. It could cause a stroke in the brain. Anticoagulants are recommended in patients predisposed to deep vein thrombosis, pulmonary embolism and stroke
as well as in patients who have already developed these conditions to prevent further progression. Unstable angina and heart attack
A patient may develop chest pain due to blockage to the flow of blood. This condition is called angina. If a clot completely blocks the flow of blood, it could result in a heart attack. Anticoagulants used for a short time may be beneficial in patients with unstable angina and heart attack. Atrial fibrillation
Atrial fibrillation is a condition where the atria or the upper chambers of the heart beat irregularly. This could result in clot formation in the atria that could travel to different organs and produce stroke and other complications. Anticoagulants given during and a few weeks after atrial fibrillation prevent embolus formation. Disseminated intravascular coagulation
In disseminated intravascular coagulation, a number of small clots are formed in the blood. Heparin is useful in this condition
Anticoagulants are also useful to prevent emboli in other condition like dialysis, prosthetic heart valves and vascular surgery such as angioplasty and stent placement.