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Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Blood clot facts
• What are blood clots?
• What causes blood clots?
• What does a blood clot look like?
• What are the risk factors for blood clots?
• What types and conditions are caused by blood clots?
• What are the symptoms of blood clots?
• How are blood clots diagnosed?
• What is the treatment for blood clots?
• What are the complications of blood clots?
• How can blood clots be prevented?
• Patient Comments: Blood Clots - Describe Your Experience
• Patient Comments: Blood Clots - Causes
• Blood Clots Index

Blood clots prevent proper circulation of blood.

Deep vein thrombosis of the leg or arm may cause permanent damage to the veins themselves and cause persistent swelling of the extremity. The life-threatening issue that may arise from deep venous clots is a clot that breaks off and embolizes to the lungs (pulmonary embolus), causing problems with lung function and oxygenation of the blood.

Arterial thrombus often is a life- or limb threatening event, since organs and cells do not get enough oxygen.

Prevention is key in thrombosis or clot formation.

Arterial thrombosis

• For arterial thrombosis, the most likely precipitating event is a plaque rupture with clot formation in the artery.
  
  
• Minimizing the risk of vascular disease requires life-long attention to the risk factors that lead to plaque buildup and "hardening" of the arteries.
  
  
• Blood pressure and cholesterol control, diabetes management, and refraining from smoking all minimize the risk of arterial disease.
  
  
• Although family history is an important risk factor, one needs to be even more vigilant about the other risk factors if there is a family history of early heart attack or stroke.

Deep vein thrombosis

The main risk factor for deep vein thrombosis risks is immobilization. It is important to move around routinely so that blood can circulate in the venous system. On long trips, it is recommended to get out of the car every couple of hours and in an airplane routinely get up and stretch.

Physicians and nurses work hard at getting people moving after surgery or while in the hospital for medical conditions. The low molecular weight heparin known as enoxaparin (Lovenox) can also be used in low doses to prevent clot formation. Patients are often given tight stockings to promote blood return from the legs and prevent pooling of blood.

In patients with atrial fibrillation, warfarin (Coumadin) was traditionally used to prevent clot formation and minimize the risk of embolus and stroke. Newer medications have been developed that prevent blood clot formation similar to warfarin and have been successfully used in patients with atrial fibrillation. These medications include dabigatran (Pradaxa), rivaroxaban (Xarelto), and apixaban (Eliquis). These newer drugs have advantages of reduced susceptibility to diet and drug interactions and convenience (lack of need for routine blood testing of the international normalized ratio or INR, as is required for warfarin therapy).

An important caution was issued by the FDA about the use of dabigatran because a clinical trial in Europe (the RE-ALIGN trial)1 was recently stopped because dabigatran users were more likely to experience strokes, heart attacks, and blood clots forming on the mechanical heart valves than were users of warfarin. There was also more bleeding after valve surgery with dabigatran use than with the use of warfarin. The FDA recommends that dabigatran not be used to prevent blood clots in patients with mechanical prosthetic heart valves.

REFERENCE:

eMedicine.com. Deep Vein Thrombosis and Thrombophlebitis.
<http://emedicine.medscape.com/article/758140-overview.>

Fauci, Anthony S., et al. Harrison's Principles of Internal Medicine. 17th ed. United States: McGraw-Hill Professional, 2008.