Chapter 147 - Acute LE DVT - introduction Flashcards
Symptoms of acute DVT
1) dull ache 2) pain 3) tenderness 4) swelling 5) erythema 6) cyanosis 7) fever
Phlegmasia cerulea dolens symptoms
1) edema 2) cyanosis 3) pain
Cause of venous gangrene
1) cancer 2) HITT 3) warfarin-mediated protein C depletion
Two factors that aid in diagnosis of DVT
1) past history of DVT 2) malignant disease
What is D-dimer
1) Product of fibrin proteolysis by plasmin 2) indicates fibrinolysis of complexed fibrin
Other causes of elevated D-dimer
1) trauma 2) pregnancy 3) surgery 4) cancer 5) thrombotic disorders
Non-compressibility of vein sensitivity and specificity on US
97% 94%
Limitation of compression ultrasound
1) poor accuracy in calf veins 2) fresh thrombi 3) small segmental thrombi 4) obese patients or significant edema
Key limitation points in duplex US in DVT
1) low risk patients may get false positive 2) duplex US cannot reliably rule out distal DVT
Risk of PE from calf muscle vein thromboses vs calf vein thromboses
CMVT 50% risk CV DVT 10-15% risk
Two different Techniques of contrast venography
1) Rabinov-Paulin technique = spot film 2) Long-leg technique = cine film Long leg has less interobserver disagreement and easier to interpret
CTV and MRV in DVT diagnosis
Both have variable results but overall 90’s for sen and spe MRI better for proximal DVT not as good below knee
What is 18F-FDG
18F-labelled fluorodeoxyglucose glucose analogue absorbed by tissue and cells with rapid metabolism
What type of cells would 18F-FDG label
1) tumor cells 2) endothelial cells 3) macrophages 4) lymphocytes
use of 18F-FDG PET/CT in DVT
sen 87.5 spe 100 help differentiate from DVT and tumor DVT
fold increase in DVT with various diseases: Heterozygous antithrombin deficiency Protein C deficiency Protein S deficiency Life risk heterozygous factor V Leiden Others
AT 5-50x protein C 3x Protein S 10x Factor V Leiden 10% others 2x or less
risk of DVT in the absence of prophylaxis after surgery of various types
hip # 50% burn 33% Ortho 36% uro 33% gen 25% neuro 23% abd 19% PAD 15%
Wells score for DVT
1) active cancer 2) paralysis/paresis/immobolization 3) major surgery in 12 weeks needing general/regional anes causing (3d bed rest) 4) tenderness along deep venous system 5) entire leg swollen 6) calf > 3cm larger than contralateral side 7) pitting edema ipsilateral 8) collateral superficial veins nonvaricose 9) previous DVT - 2 points if other diagnosis possible
Where do you measure calf circumference for DVT
10 cm below tibial tuberosity
Well score stratified risk for high intermediate and low risk
High = 47% intermediate 12% low 4%
Negative D dimer in low or intermediate wells score patients treatment
No further workup risk < 0.6% in 3 months
Negative D dimer in high risk patient PE risk
15%
Problem in using wells score in hospitalized patients
underestimates risk of DVT/PE
Algorithm for clinically likely DVT
FIGURE 147.7
Algorithm for clinically unlikely DVT
FIGURE 147.8
Rate of recurrent DVT in first year
11-18%
Challenges in detecting recurrent DVT
1) All are considered high risk 2) Ultrasound findings hard to interpret 3) post-thrombotic changes similar to acute DVT
How to determine age of thrombus in DVT
1) radiolabelled recombinant TPA for 30 day + old thrombus 2) MRI for 6 month + old thrombus
Landmark paper that anticoagulation is used to treat DVT
Barritt and Jordan 1961
Contraindication to outpatient treatment of acute DVT
1) high bleed risk 2) severe symptomatic venous obstruction 3) thrombocytopenia 4) poor hepatic function 5) unstable renal function 6) non-compliance 7) poor social support
Non-anticoagulation treatments of acute DVT
1) compression therapy 2) leg elevation 3) early ambulation
Goals of DVT treatment x2
1) immediate reduction of M&M in short term 2) reduction of late post-thrombotic morbidity
Current treatment of calf/distal DVT
1) controversial surveillance vs anticoag 3 month 2) factors to trigger anticoag: 1) elevated d-dimer 2) thrombotic burden 3) history of VTE 4) thrombophilic states
Femoral vein dvt vs popliteal vein dvt symptoms
femoral is mild because of popliteal drain via profunda to CFV popliteal DVT is morbid
Anticoagulation alone for iliofemoral DVT long term problems
1) intraluminal scar with type 1 and 3 collagen 2) 95% valvular dysfunction 3) 30% venous claudication/ulceration 4) recurrence due to May Thurner
Unfractionated heparin Mechanism bleeding risk other risk
Factor II and X inhibition via antithrombin activation 2% major bleed HIT 0.5-2%
LMWH names Mechanism bleeding risk other risk
Enoxaparin, dalteparin, tinzaparin Selective factor X inhibition via antithrombin activation 2% major bleed HIT < 1%
Fondaparinux Mechanism bleeding risk other risk
Selective factor X inhibition via antithrombin activation 1.2% major bleed Thrombocytopenia 0.5%
Parenteral DTI names Mechanism bleeding risk other risk
Argatroban, bivalirudin direct factor II inhibitor 1.3% major bleed (A), 3.5% major bleed (B) hypotension, tachycardia
Warfarin Mechanism bleeding risk other risk
Vitamin K dependent factor inhibition (2, 7, 9, 10) 1.2-1.9% major bleed food drug interactions
DOAC names mechanism bleeding risk other risk
direct oral inhibitor of factor Xa apixaban, rivaroxaban, edoxaban Major bleed 0.6-1.4% Increased exposure in renal failure eGFR < 30 apixaban has least renal clearance and does not need dose adjustment increased exposure and liver toxic for rivaroxaban and edoxaban only
Therapeutic range of heparin
1.5-2.5x aPTT control value plasma heparin assay to get level 0.3-0.7 IU/ml
Discovery of LMWH year
1976
Half life of LMWH
3-5 hours
ACCP guideline for anticoagulation in cancer
first 3 months with LMWH
Treatment of HITT
Argatroban or bivalirudin
Why do antibiotics affect warfarin dosing
Destruction of gut flora that produced vitamin K
EINSTEIN trial key points
1) rivaroxaban reduces recurrent VTE 2.1 vs 3%
Dabigatran mechanism bleeding risk other risk
DOAC but factor IIa inhibitor 1.6% major bleed renal clearance
Antidote for dabigatran and dose
Idarucizumab 5g IV
Use of graduated compression stockings in acute DVT
controversial no clear benefit in reducing post-thrombotic syndrome
PROLONG trial key points
1) abnormal d-dimer randomized to anticoag or stop anticoag 2) increased recurrence in patients that did not receive ongoing treatment
WARFASA and ASPIRE trials key points
32% reduction in VTE and 34% reduction in major vascular event without significant bleeding when ASA is used in addition
AMPLIFY-EXT trial key points
Apixaban vs placebo in preventing recurrent DVT after 6-12 months of therapeutic anticoagulation 1) 2.5 or 5 mg BID had lower VTE/death than placebo 1.7 vs 8.8% 2) bleeding higher with treatment 2.3 vs 3.0 vs 4.2% 3) NNT = 14 to prevent 1 VTE 4) NNH = 200 to cause bleed Limitation 15% over age 75 few patients with CKD > 3
