1、Deep vein thrombosis,Xiang Yu Cheng,第一页，共四十六页。,What Is Deep Vein Thrombosis?,The earliest case of DVT was described around 600-900 BC.At some point,the increased incidence of DVT in women after childbirth was noticed,and in the late 1700s,a public health recommendation was issued to encourage women
2、to breast feed as a means to prevent this phenomenon;the DVT was called milk leg,as it was thought to result from milk building up in the leg.,第二页，共四十六页。,What Is Deep Vein Thrombosis?,Deep vein thrombosis,or DVT,is a blood clot that forms in a vein deep in the body.Blood clots occur when blood thick
3、ens and clumps together.,第三页，共四十六页。,What Is Deep Vein Thrombosis?,A blood clot in a deep vein can break off and travel through the blood.The embolus could travel to an artery in the lungs and block blood flow.This condition is calledpulmonary embolism,or PE.,第四页，共四十六页。,Epidemiology,Deep vein thrombo
4、sis,*Diagnoses of DVT and PE are not mutually exclusive;an estimated 78,511 patients received diagnoses of both DVT and PE.VTE estimates include patients with diagnoses of either DVT or PE.,第五页，共四十六页。,Epidemiology,Deep vein thrombosis,According to the most recent ACCP guidelines,VTE remains the seco
5、nd most common cause of protracted hospital stay and the third most common cause of excess mortality among 7 million patients discharged from 944 acute care hospitals in the US.,第六页，共四十六页。,Causes,German pathologistRudolf Virchowpostulated the interplay of three processes resulting in venous thrombos
6、is,now known asVirchows triad:,Deep vein thrombosis,In keeping with Virchows concept,alterations of the coagulation system that induce a hypercoagulable state also confer an increased risk of DVT.,第七页，共四十六页。,Causes,German pathologistRudolf Virchowpostulated the interplay of three processes resulting
7、 in venous thrombosis,now known asVirchows triad:,Deep vein thrombosis,第八页，共四十六页。,Causes,The blood flow pattern in the valves can cause hypoxemia,which is worsened by venous stasis,activates pathways-ones that includehypoxia-inducible factor-1andearly-growth-response protein 1.Hypoxia-inducible fact
8、or-1 and early-growth-response protein 1 contribute to monocyte association with endothelial proteins,such asP-selectin,prompting monocytes to release tissue factor-filledmicrovesicles,which presumably begin clotting after binding to the endothelial surface.9,Deep vein thrombosis,第九页，共四十六页。,Causes,I
9、ndependent Risk Factors for DVT,Age is an independent risk factor for thrombotic disease.The majority of venous thrombi occur in either the superficial or deep veins of the leg.A DVT is stationary clotting blood adhered to the deep vein of the pelvis or an extremity and usually occurs in the calf or
10、 thigh.VTE denotes an obstruction arising from the formation of a clot in the venous circulation carried by the blood from the site of origin to plug another vessel.,Deep vein thrombosis,第十页，共四十六页。,Causes,Independent Risk Factors for DVT,Deep vein thrombosis,第十一页，共四十六页。,Signs and symptoms,Common sig
11、ns and symptoms of DVT include：Pain Swelling Warmth Redness or discoloration Distention of surface veins,Deep vein thrombosis,第十二页，共四十六页。,Signs and symptoms,Common signs and symptoms of DVT include：Pain Swelling Warmth Redness or discoloration Distention of surface veins,Deep vein thrombosis,第十三页，共四
12、十六页。,Signs and symptoms,In most suspected cases,DVT is ruled out after evaluation,and symptoms are more often due to other causes,such ascellulitis,Bakers cyst,musculoskeletal injury,orlymph edema.Otherdifferential diagnosesincludehematoma,tumors,venous or arterialaneurysms,and connective tissue dis
13、orders.,Deep vein thrombosis,第十四页，共四十六页。,Diagnosis,Probability:In those with suspected DVT,a clinical assessment of probability can be useful to determine which tests to perform.The most studiedclinical prediction ruleis the Wells score.,Deep vein thrombosis,第十五页，共四十六页。,Diagnosis,Deep vein thrombosi
14、s,第十六页，共四十六页。,Diagnosis,Physical Exam:symptoms Half of those with the condition HAVE NO SYMPTOMS.Signs and symptoms alone are not sufficientlysensitive or specificto make a diagnosis,but when considered in conjunction withknown risk factorscan help determine thelikelihoodof DVT.,Deep vein thrombosis
15、,第十七页，共四十六页。,Diagnosis,DVT diagnosis requires the use ofimagingdevices such asultrasound.Clinical assessments,which predict DVT likelihood,can help determine if aD-dimertest is useful.In those not highly likely to have DVT,a normal D-dimer result can rule out a diagnosis.,Deep vein thrombosis,第十八页，共
16、四十六页。,Diagnosis,D-dimer:Afibrin degradation product,and an elevated level can result fromplasmindissolving a clot,or other conditions.,Deep vein thrombosis,第十九页，共四十六页。,Diagnosis,For those with a low or moderate probability of DVT,a D-dimer level might be obtained,which excludes a diagnosis if results are normal.An elevated level requires further investigation with diagnostic imaging to confirm or exclude the diagnosis.,Deep vein thrombosis,第二十页，共四十六页。,Diagnosis,For a suspected first leg DVT in a
