深静脉血栓概述

1、 Deep vein thrombosisWhat 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 to breast feed as a mea

2、ns 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?Deep 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 together.What Is

3、 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.EpidemiologyDeep vein thrombosis* Diagnoses of DVT and PE are not mutually exclusiv

4、e; 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 stay and the third mo

5、st common cause of excess mortality among 7 million patients discharged from 944 acute care hospitals in the US.CausesGerman pathologistRudolf Virchowpostulated the interplay of three processes resulting in venous thrombosis, now known asVirchows triad: Deep vein thrombosisIn keeping with Virchows c

6、oncept, alterations of the coagulation system that induce a hypercoagulable state also confer an increased risk of DVT. CausesGerman pathologistRudolf Virchowpostulated the interplay of three processes resulting in venous thrombosis, now known asVirchows triad: Deep vein thrombosisCausesThe blood fl

7、ow 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 factor-1 and early-growth-response protein 1 contribute to monocyte association with endothelial pro

8、teins, such asP-selectin, prompting monocytes to release tissue factor-filledmicrovesicles, which presumably begin clotting after binding to the endothelial surface.9Deep vein thrombosisCausesIndependent Risk Factors for DVTAge is an independent risk factor for thrombotic disease.The majority of ven

9、ous 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 venous circulation carried by

10、the blood from the site of origin to plug another vessel.Deep vein thrombosisCausesIndependent Risk Factors for DVTDeep vein thrombosisSigns and symptomsCommon signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of surface veinsDeep vein thrombosisSigns and sy

11、mptomsCommon signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of surface veinsDeep vein thrombosisSigns and symptomsIn most suspected cases, DVT is ruled out after evaluation, and symptoms are more often due to other causes, such ascellulitis,Bakers cyst, m

12、usculoskeletal injury, orlymph edema.Otherdifferential diagnosesincludehematoma, tumors, venous or arterialaneurysms, and connective tissue disorders.Deep vein thrombosisDiagnosisProbability: In those with suspected DVT, a clinical assessment of probability can be useful to determine which tests to

13、perform. The most studiedclinical prediction ruleis the Wells score.Deep vein thrombosisDiagnosisDeep vein thrombosisDiagnosisPhysical 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 cons

14、idered in conjunction withknown risk factorscan help determine thelikelihoodof DVT.Deep vein thrombosisDiagnosisDVT 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 lik

15、ely to have DVT, a normal D-dimer result can rule out a diagnosis.Deep vein thrombosisDiagnosisD-dimer: Afibrin degradation product, and an elevated level can result fromplasmindissolving a clot, or other conditions.Deep vein thrombosisDiagnosisFor those with a low or moderate probability of DVT, a

16、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 thrombosisDiagnosisFor a suspected first leg DVT in a low-probability situation, theAmerican Colle

17、ge of Chest Physicians(ACCP) recommends testing either D-dimer levels with moderate or high sensitivity or compression ultrasound of the proximal veins. Deep vein thrombosisDiagnosisImaging: Imaging tests of the veins are used in the diagnosis of DVT. Ultrasound, CT scan venography, MRI venography,

18、or MRI of the thrombus are also possibilities.Deep vein thrombosisDiagnosisUltrasound: a sensitive and specific tool for the assessment of patients presenting with symptoms suggestive of lower extremity DVT.Deep vein thrombosisDiagnosisDopler UltrasoundDeep vein thrombosisDiagnosisContrastVenography

19、: Thegold standard methods to reveal whether the venous supply has been obstructed. Deep vein thrombosis(a) direct manual contrast injection into the guiding catheter (direct venography technique, DVT)and (b) occlusion of coronary sinus by a Swan-Ganz catheter.DiagnosisContrastVenography: Thegold st

20、andard 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 patient with deep venous thrombosi

21、s.Deep vein thrombosisDiagnosisThe AAFP and the ACP have published a clinical practice guideline that summarizes current approaches for the diagnosis of DVTClinical prediction rules should be used to estimate the pretest probability of DVT .In selected patients with a low pretest probability of DVT

22、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 diagnostic imaging studies.Deep ve

23、in thrombosisDiagnosisDeep vein thrombosisTreatmentThe main goals of treatment for DVT include prevention of PE, VTE and recurrent thrombosis. Once VTE is suspected, anticoagulation should be started immediately unless there is a contraindication. Deep vein thrombosisTreatmentMedical Management: Ant

24、icoagulationUnfractionated Heparin 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 thrombosisTreatmentMedical Management: Anticoagulatio

25、nLow-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 a once-daily injection (1.5 mg/kg/d

26、ay) or twice daily (1 mg/kg every 12 hr). Deep vein thrombosisTreatmentMedical Management: AnticoagulationFactor Xa Inhibitors Fondaparinux is an indirect factor Xa inhibitor that can be used as VTE prophylaxis in medical patients, those undergoing orthopedic procedures (total hip and knee arthropla

27、sty), and those undergoing abdominal surgery. Deep vein thrombosisTreatmentMedical Management: AnticoagulationWarfarin Warfarin remains the mainstay of therapy for long-term treatment of VTE. It may be initiated once anticoagulation with UFH, LWMH, or fondaparinux has been started (and which should

28、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 thrombosisTreatmentMedical Management: AnticoagulationNew Oral AnticoagulantsDabigatran：direct thrombin inhibitorRivaroxaban：factor Xa inhibitorDeep vein

29、 thrombosisTreatmentMedical Management: AnticoagulationThrombolytic TherapyThrombolytic 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 has been no clearly established shor

30、t-term mortality benefit. Deep vein thrombosisTreatmentMedical Management: Surgical/Mechanical interventionPulmonary Embolectomy According to ACCP guidelines, pulmonary embolectomy for the initial treatment of PE is reserved for patients with massive PE (documented angiographically if possible), sho

31、ck despite heparin and resuscitation efforts, and failure of thrombolytic therapy or a contraindication to itsDeep vein thrombosisTreatmentMedical Management: Surgical/Mechanical interventionVena Caval Interruption Current guidelines recommend against the routine use of inferior vena cava (IVC) filt

32、ers 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.Deep vein thrombosisTreatmentThe

33、 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 thrombosisTreatmentAlthough the risk of recurrence decreases

34、with longer durations of anticoagulation, clinicians must weigh the risk of bleeding against the risk of new thrombosis.Deep vein thrombosisPreventionApproximately two-thirds of all DVT events result from hospitalization, yet only one third of all hospitalized patients at risk receive adequate proph

35、ylaxis.PE 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 thrombosisPreventionApproximately two-thirds of all DVT events result fro