National Heart, Lung, and Blood Institute. (2011). What is Deep Vein Thrombosis? Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/dvt National Heart, Lung, and Blood Institute. (2011). What is Deep Vein Thrombosis? Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/dvNational Heart, Lung, and Blood Institute. (2011). What is Deep Vein Thrombosis? Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/dvt National Heart, Lung, and Blood