Deepveinthrombosis深静脉血栓

1、 Deep vein thrombosisXiang Yu ChengWhat Is Deep Vein Thrombosis?pThe earliest case of DVT was described around 600-900 BC. pAt 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 to brea

2、st 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.What Is Deep Vein Thrombosis?pDeep vein thrombosis, or DVT, is a blood clot that forms in a vein deep in the body. Blood clots occur when blood thickens and clumps

3、 together.What Is Deep Vein Thrombosis?pA 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 called pulmonary embolism, or PE.EpidemiologyDeep vein thrombosis* Diagnoses of DVT and PE are no

4、t 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.EpidemiologyDeep vein thrombosisAccording to the most recent ACCP guidelines, VTE remains the second most common cause of protracted hospital st

5、ay and the third most common cause of excess mortality among 7 million patients discharged from 944 acute care hospitals in the US.CausespGerman pathologist Rudolf Virchow postulated the interplay of three processes resulting in venous thrombosis, now known asVirchowstriad:Deep vein thrombosisIn kee

6、ping with Virchows concept, alterations of the coagulation system that induce a hypercoagulable state also confer an increased risk of DVT. CausespGerman pathologist Rudolf Virchow postulated the interplay of three processes resulting in venous thrombosis, now known asVirchowstriad:Deep vein thrombo

7、sisCausesThe blood flow pattern in the valves can cause hypoxemia, which is worsened by venous stasis, activates pathways - ones that include hypoxia-inducible factor-1and early-growth-response protein 1. Hypoxia-inducible factor-1 and early-growth-response protein 1 contribute to monocyte associati

8、on with endothelial proteins, such as P-selectin, prompting monocytes to release tissue factor-filled microvesicles, which presumably begin clotting after binding to the endothelial surface.9Deep vein thrombosisCausespIndependent Risk Factors for DVT Age is an independent risk factor for thrombotic

9、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 thigh. VTE denotes an obstruction arising from the formation of a clot in the

10、venous circulation carried by the blood from the site of origin to plug another vessel.Deep vein thrombosisCausespIndependent Risk Factors for DVTDeep vein thrombosisSigns and symptomspCommon signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of surface veins

11、Deep vein thrombosisSigns and symptomspCommon signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of surface veinsDeep vein thrombosisSigns and symptomspIn most suspected cases, DVT is ruled out after evaluation, and symptoms are more often due to other causes

12、, such as cellulitis, Bakers cyst, musculoskeletal injury, or lymph edema.pOther differential diagnoses include hematoma, tumors, venous or arterial aneurysms, and connective tissue disorders.Deep vein thrombosisDiagnosispProbability:In those with suspected DVT, a clinical assessment of probability

13、can be useful to determine which tests to perform. The most studied clinical prediction rule is the Wellsscore.Deep vein thrombosisDiagnosisDeep vein thrombosisDiagnosispPhysicalExam:symptoms Half of those with the condition HAVENOSYMPTOMS. Signs and symptoms alone are not sufficiently sensitive or

14、specific to make a diagnosis, but when considered in conjunction with known risk factors can help determine the likelihood of DVT.Deep vein thrombosisDiagnosispDVT diagnosis requires the use of imaging devices such as ultrasound. Clinical assessments, which predict DVT likelihood, can help determine

15、 if a D-dimer test is useful. pIn those not highly likely to have DVT, anormalD-dimerresultcanruleoutadiagnosis.Deep vein thrombosisDiagnosispD-dimer:A fibrin degradation product, and an elevated level can result from plasmin dissolving a clot, or other conditions.Deep vein thrombosisDiagnosis For t

16、hose 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 thrombosisDiagnosis For a suspected first leg DV

17、T in a low-probability situation, the American College of Chest Physicians (ACCP) recommends testing either D-dimer levels with moderate or high sensitivity or compression ultrasound of the proximal veins. Deep vein thrombosisDiagnosispImaging:Imaging tests of the veins are used in the diagnosis of

18、DVT. Ultrasound, CTscanvenography, MRIvenography, or MRIofthethrombusare also possibilities.Deep vein thrombosisDiagnosispUltrasound:a sensitive and specific tool for the assessment of patients presenting with symptoms suggestive of lower extremity DVT.Deep vein thrombosisDiagnosispDoplerUltrasoundD

19、eep vein thrombosisDiagnosispContrastVenography:The gold standard methods to reveal whether the venous supply has been obstructed. Deep vein thrombosis(a)directmanualcontrastinjectionintotheguidingcatheter(direct venography technique, DVT)and(b)occlusionofcoronarysinusbyaSwan-Ganzcatheter.Diagnosisp

20、ContrastVenography:The gold standard methods to reveal whether the venous supply has been obstructed. Unilateral above knee DVT in a patient with a recent right hemisphere cerebral infarction.A 19-year-old man with May-Thurner syndrome with swelling of the left lower extremity.Phlebography in a pati

21、ent with deep venous thrombosis.Deep vein thrombosisDiagnosispThe AAFP and the ACP have published a clinical practice guideline that summarizes current approaches for the diagnosis of DVT Clinical prediction rules should be used to estimate the pretest probability of DVT . In selected patients with

22、a low pretest probability of DVT or PE, a negative high-sensitivity D-dimer test indicates a low likelihood of VTE. Ultrasound is recommended for patients with intermediate to high pretest probability of DVT in the legs. Patients with intermediate or high pretest probability of PE require additional

23、 diagnostic imaging studies.Deep vein thrombosisDiagnosisDeep vein thrombosisTreatmentpThe main goals of treatment for DVT include prevention of PE, VTE and recurrent thrombosis. pOnce VTE is suspected, anticoagulation should be started immediately unless there is a contraindication. Deep vein throm

24、bosisTreatmentpMedicalManagement:Anticoagulation UnfractionatedHeparin Weight-based dosing of UFH (80 U/kg bolus followed by 18 U/kg/hr IV infusion) has been shown to achieve a therapeutic activated partial thromboplastin time (aPTT) more rapidly than fixed-dose regimens. Deep vein thrombosisTreatme

25、ntpMedicalManagement:Anticoagulation Low-Molecular-Weight-Heparin LMWH is administered as a weight-based subcutaneous injection. In the current ACCP guidelines, LMWH is recommended over UFH for the initial treatment of DVT or PE. Enoxaparin, the most commonly used agent in the US, is given either as

26、 a once-daily injection (1.5 mg/kg/day) or twice daily (1 mg/kg every 12 hr). Deep vein thrombosisTreatmentpMedicalManagement:Anticoagulation FactorXaInhibitors Fondaparinux is an indirect factor Xa inhibitor that can be used as VTE prophylaxis in medical patients, those undergoing orthopedic proced

27、ures (total hip and knee arthroplasty), and those undergoing abdominal surgery. Deep vein thrombosisTreatmentpMedicalManagement:Anticoagulation Warfarin Warfarin remains the mainstay of therapy for long-term treatment of VTE. It may be initiated once anticoagulation with UFH, LWMH, or fondaparinux h

28、as been started (and which should be continued as overlap treatment for a minimum of 5 days and until the international normalized ratio INR is at least 2.0 for 24 hours).Deep vein thrombosisTreatmentpMedicalManagement:Anticoagulation NewOralAnticoagulants Dabigatran：direct thrombin inhibitor Rivaro

29、xaban：factor Xa inhibitorDeep vein thrombosisTreatmentpMedicalManagement:Anticoagulation ThrombolyticTherapy Thrombolytic therapy for DVT may be beneficial in selected patients, and although it can be administered systemically. Thrombolytic therapy for acute PE remains controversial because there ha

30、s been no clearly established short-term mortality benefit. Deep vein thrombosisTreatmentpMedicalManagement:Surgical/Mechanicalintervention PulmonaryEmbolectomy According to ACCP guidelines, pulmonary embolectomy for the initial treatment of PE is reserved for patients with massive PE (documented an

31、giographically if possible), shock despite heparin and resuscitation efforts, and failure of thrombolytic therapy or a contraindication to itsDeep vein thrombosisTreatmentpMedicalManagement:Surgical/Mechanicalintervention VenaCavalInterruption Current guidelines recommend against the routine use of

32、inferior vena cava (IVC) filters for the treatment of VTE. Indications for the placement of IVC filters include a contraindication to anticoagulation, complications of anticoagulation, recurrent thromboembolism despite adequate anticoagulant therapy, and patients undergoing pulmonary embolectomy.Dee

33、p vein thrombosisTreatmentpThe duration of treatment following the diagnosis of DVT depends on the risk of recurrence, including idiopathic DVT or PE, certain underlying hypercoagulable states such as the antiphospholipid syndrome, and underlying malignancy. Deep vein thrombosisTreatmentpAlthough th

34、e risk of recurrence decreases with longer durations of anticoagulation, clinicians must weigh the risk of bleeding against the risk of new thrombosis.Deep vein thrombosisPreventionpApproximately two-thirds of all DVT events result from hospitalization, yet only one third of all hospitalized patients at risk receive adequate prophylaxis.pPE is the most common preventable cause of hospital death in the US. Without prophylaxis, the incidence of hospital-acquired DVT is 10% to 20% among medical patients and higher (15% to 40%) among surgical patients.Deep vein thrombosisPreventi