thumb|right|Animation showing the formation of an occlusive blood clot in a vein. Several [[platelets attach to the lips of the valve, narrowing the opening and causing more platelets and red blood cells to pool and clot. Clotting of immobile blood on both sides of the blockage can cause the clot to spread in both directions. Acute blockage (embolism) of a blood vessel by a thrombus that has detached from its place of formation (on the wall of a vessel) and entered the circulating blood. As a result of this blockage, blood flow in the vessel stops—a condition called thromboembolism.]]
Thromboembolism is a condition in which a blood clot (thrombus) breaks off from its original site and travels through the bloodstream (as an embolus) to obstruct a blood vessel, causing tissue ischemia and organ damage. Thromboembolism can affect both the venous and arterial systems, with different clinical manifestations and management strategies.
Venous thromboembolism
Venous thromboembolism (VTE) comprises the following conditions:
Signs and symptoms
VTE can present with various symptoms, such as painful leg swelling, chest pain, dyspnea, hemoptysis, syncope, and even death, depending on the location and extent of the thrombus. VTE can also cause long-term complications, such as recurrent VTE, post-PE syndrome, chronic thromboembolic pulmonary hypertension (CTEPH), and post-thrombotic syndrome (PTS).
Treatment
The mainstay of VTE management is anticoagulation therapy, which prevents thrombus propagation and embolization. Such treatment reduces the risk of recurrence. Those whose thrombosis is brought on by a minor reversible risk factor have a higher change of recurrent thrombus and require longer treatment time. These events include long flights, estrogen therapy, pregnancy and peripartum, and minor leg traumas. Medications, such as pentoxifylline, have a limited role in the treatment of PTS. After PE, patients should be monitored for signs and symptoms of CTEPH, which is a rare but serious complication of VTE. Ventilation-perfusion scanning and echocardiography are the initial diagnostic tests for CTEPH, and patients with confirmed or suspected CTEPH should be evaluated for potential treatments, such as pulmonary thromboendarterectomy, balloon pulmonary angioplasty, or vasodilator therapies.
- High risk: bone fracture (especially of the hip or leg), recent hip or knee replacement, recent major general surgery, spinal cord injuries, and major trauma. These conditions are generally due to atherosclerosis. There are also several nonatherosclerotic conditions that can lead to ATE. Included in these conditions are giant cell arteritis, Takayasu's arteritis, Ehlers-Danlos syndrome, Marfan's syndrome, pseudoxanthoma elasticum, and Kawasaki's disease, and radiation induced arteritis.