Deep vein thrombosis深静脉血栓

1、Deep vein thrombosis,Xiang Yu Cheng,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 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?,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 clump

3、s together.,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.,Epidemiology,Deep vein thrombosis,* Diagnoses of DVT and PE ar

4、e 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.,Epidemiology,Deep vein thrombosis,According to the most recent ACCP guidelines, VTE remains the second most common cause of protracted hosp

5、ital stay and the third most common cause of excess mortality among 7 million patients discharged from 944 acute care hospitals in the US.,Causes,German pathologistRudolf Virchowpostulated the interplay of three processes resulting in venous thrombosis, now known asVirchows triad:,Deep vein thrombos

6、is,In keeping with Virchows concept, alterations of the coagulation system that induce a hypercoagulable state also confer an increased risk of DVT.,Causes,German pathologistRudolf Virchowpostulated the interplay of three processes resulting in venous thrombosis, now known asVirchows triad:,Deep vei

7、n thrombosis,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 factor-1 and early-growth-response protein 1 contribute to monocyte

8、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,Causes,Independent Risk Factors for DVT,Age is an independent risk factor for th

9、rombotic 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 clo

10、t in the venous circulation carried by the blood from the site of origin to plug another vessel.,Deep vein thrombosis,Causes,Independent Risk Factors for DVT,Deep vein thrombosis,Signs and symptoms,Common signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of

11、surface veins,Deep vein thrombosis,Signs and symptoms,Common signs and symptoms of DVT include： Pain Swelling Warmth Redness or discoloration Distention of surface veins,Deep vein thrombosis,Signs and symptoms,In most suspected cases, DVT is ruled out after evaluation, and symptoms are more often du

12、e to other causes, such ascellulitis,Bakers cyst, musculoskeletal injury, orlymph edema. Otherdifferential diagnosesincludehematoma, tumors, venous or arterialaneurysms, and connective tissue disorders.,Deep vein thrombosis,Diagnosis,Probability: In those with suspected DVT, a clinical assessment of

13、 probability can be useful to determine which tests to perform. The most studiedclinical prediction ruleis the Wells score.,Deep vein thrombosis,Diagnosis,Deep vein thrombosis,Diagnosis,Physical Exam: symptoms Half of those with the condition HAVE NO SYMPTOMS. Signs and symptoms alone are not suffic

14、ientlysensitive or specificto make a diagnosis, but when considered in conjunction withknown risk factorscan help determine thelikelihoodof DVT.,Deep vein thrombosis,Diagnosis,DVT diagnosis requires the use ofimagingdevices such asultrasound. Clinical assessments, which predict DVT likelihood, can h

15、elp 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,Diagnosis,D-dimer: Afibrin degradation product, and an elevated level can result fromplasmindissolving a clot, or other conditions.,Deep vein thromb

16、osis,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,Diagnosis,For a

17、suspected first leg DVT in a low-probability situation, theAmerican 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 thrombosis,Diagnosis,Imaging: Imaging tests of the veins are use

18、d in the diagnosis of DVT. Ultrasound, CT scan venography, MRI venography, or MRI of the thrombus are also possibilities.,Deep vein thrombosis,Diagnosis,Ultrasound: a sensitive and specific tool for the assessment of patients presenting with symptoms suggestive of lower extremity DVT.,Deep vein thro

19、mbosis,Diagnosis,Dopler Ultrasound,Deep vein thrombosis,Diagnosis,ContrastVenography: 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) occlus

20、ion of coronary sinus by a Swan-Ganz catheter.,Diagnosis,ContrastVenography: Thegold 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 s

21、welling of the left lower extremity.,Phlebography in a patient with deep venous thrombosis.,Deep vein thrombosis,Diagnosis,The 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 estimat

22、e the pretest probability of DVT . In selected patients with 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 inte

23、rmediate or high pretest probability of PE require additional diagnostic imaging studies.,Deep vein thrombosis,Diagnosis,Deep vein thrombosis,Treatment,The main goals of treatment for DVT include prevention of PE, VTE and recurrent thrombosis. Once VTE is suspected, anticoagulation should be started

24、 immediately unless there is a contraindication.,Deep vein thrombosis,Treatment,Medical Management: Anticoagulation Unfractionated 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

25、) more rapidly than fixed-dose regimens.,Deep vein thrombosis,Treatment,Medical Management: 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.

26、 Enoxaparin, the most commonly used agent in the US, is given either as a once-daily injection (1.5 mg/kg/day) or twice daily (1 mg/kg every 12 hr).,Deep vein thrombosis,Treatment,Medical Management: Anticoagulation Factor Xa Inhibitors Fondaparinux is an indirect factor Xa inhibitor that can be use

27、d as VTE prophylaxis in medical patients, those undergoing orthopedic procedures (total hip and knee arthroplasty), and those undergoing abdominal surgery.,Deep vein thrombosis,Treatment,Medical Management: Anticoagulation Warfarin Warfarin remains the mainstay of therapy for long-term treatment of

28、VTE. It may be initiated once anticoagulation with UFH, LWMH, or fondaparinux has 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 thrombosis,Treatment,Medical Management

29、: Anticoagulation New Oral Anticoagulants Dabigatran：direct thrombin inhibitor Rivaroxaban：factor Xa inhibitor,Deep vein thrombosis,Treatment,Medical Management: Anticoagulation Thrombolytic Therapy Thrombolytic therapy for DVT may be beneficial in selected patients, and although it can be administe

30、red systemically. Thrombolytic therapy for acute PE remains controversial because there has been no clearly established short-term mortality benefit.,Deep vein thrombosis,Treatment,Medical Management: Surgical/Mechanical intervention Pulmonary Embolectomy According to ACCP guidelines, pulmonary embo

31、lectomy for the initial treatment of PE is reserved for patients with massive PE (documented angiographically if possible), shock despite heparin and resuscitation efforts, and failure of thrombolytic therapy or a contraindication to its,Deep vein thrombosis,Treatment,Medical Management: Surgical/Me

32、chanical intervention Vena Caval Interruption Current guidelines recommend against the routine use of 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 thr

33、omboembolism despite adequate anticoagulant therapy, and patients undergoing pulmonary embolectomy.,Deep vein thrombosis,Treatment,The duration of treatment following the diagnosis of DVT depends on the risk of recurrence, including idiopathic DVT or PE, certain underlying hypercoagulable states suc

34、h as the antiphospholipid syndrome, and underlying malignancy.,Deep vein thrombosis,Treatment,Although the risk of recurrence decreases with longer durations of anticoagulation, clinicians must weigh the risk of bleeding against the risk of new thrombosis.,Deep vein thrombosis,Prevention,Approximate

35、ly two-thirds of all DVT events result from hospitalization, yet only one third of all hospitalized patients at risk receive adequate prophylaxis. 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 thrombosis,Prevention,Approximately two-thirds of all DVT events result from hospitalization, yet only one third of all hospitalized pat