Blood Clot Prevention
A clot formation can be especially dangerous if it blocks blood flow to organs or tissues. For example, blockage of the coronary arteries (the blood vessels that directly supply oxygen to the heart muscle itself) can result in myocardial infarction (a heart attack), and death of heart muscle tissue.
An unstable thrombus can break away from the vessel wall and cascade freely through the bloodstream. This thrombus can become problematic if it becomes wedged in a blood vessel too small to allow its passage, obstructing blood flow and impairing oxygen delivery to tissue. This blockage is called an embolism. Cerebral embolism is one such example—an embolism in the small arteries of the brain can cause an embolic stroke.
Arterial thrombosis is associated with several life-threatening complications. Clots in the veins (venous thrombosis) of the legs are relatively common, and pose a significant risk of forming emboli that can travel to the lungs, causing a potentially fatal pulmonary embolism.
Complications of Thrombosis
Conditions caused by arterial thrombosis (blockage of arteries that carry oxygen-rich blood from the heart to other tissues):
- Stroke: either slow-developing caused by thrombi, or rapid-onset caused by embolism.
- Transient ischemic attack (TIA): a "mini-stroke" without tissue death.
- Myocardial infarction (heart attack): blockage of the coronary arteries that supply oxygen to the heart muscle.
- Pulmonary embolism: life-threatening blockage of arteries in the lungs, starving the body of oxygen. Some estimates place the incidence of pulmonary embolism at more than 180,000 new cases per year, making it the third most common life-threatening cardiovascular disease in the United States.5 A blood clot that leads to pulmonary embolism often forms in the legs as deep vein thrombosis (DVT), but can also form in the atrium in those with atrial fibrillation. In about 40% of cases, the origin of the emboli is unknown.6
- Angina pectoris: reduction of blood supply to the heart, typically resulting in severe chest pain.
Conditions caused by venous thrombosis (blockage of veins that carry oxygen-poor blood back to the heart):
- Deep vein thrombosis (DVT): a clot formed in a deep vein, usually in the legs. Quite common; data suggest the lifetime risk of DVT is about 5%.7 Unstable clots formed from DVT have the potential to break free and travel to the artery that supplies deoxygenated blood to the lungs, where they can cause a potentially fatal pulmonary embolism. Damage from DVT can also lead to post-thrombotic syndrome, a condition typified by leg pain, heaviness, swelling, or ulceration. More than one-third of women with DVT develop post-thrombotic syndrome.8
- Portal vein thrombosis: a rare blockage of the vein that carries blood from the abdomen to the liver. Portal vein thrombosis is relatively uncommon and usually associated with liver disease.9
- Renal vein thrombosis: a blockage of the vein that drains blood from kidney. This type of thrombosis is relatively uncommon and often associated with trauma to the abdomen.