Thrombosis Flashcards
Thrombophilias that require LMWH in the antepartum and postpartum period.
Homozygous FVL, combine thrombophilias, APLA (plus ASA)
If + FmHx- Prothrombin 20210A, Antithrombin III
APLA clinical and lab criteria
Clinical:
Arterial or venous thrombosis or biopsy confirmed microthrombi in any organ
3 or more early pregnancy loss (<10 weeks)
1 or more pregnancy loss at >10 weeks or premature labour at <34 weeks related to preterm preeclampsia
Lab: (two positive measurements 12 weeks apart)
Positive Lupus Anticoagulant (must not be done on heparin, LMWH, DOACs or warfarin)
Anti B2 glycoprotein IgG or IgM >40 units
Anti-cardiolipin IgG or IgM >40 units
5 causes of acquired Protein S and C deficiency
Protein C
- Warfarin
- Liver disease
- Vitamin K deficiency
- Acute thrombosis
- Protein losing enteropathy (IBD, nephrotic syndrome)
Protein S
*same as above + pregnancy/HRT/OCP and acute inflammatory states
Others: neonate, DIC
5 causes of acquired antithrombin deficiency
- Heparin
- L-asparginase
- Liver disease
- DIC & sepsis
- Acute thrombosis
- Protein losing enteropathy (nephrotic syndrome)
3 in vivo inhibitors of fibrinolysis
- Thrombin activatable fibrinolysis inhibitor (TAFI)—>inhibits both FDPs and plasminogen
- Plasminogen activator inhibitor (PAI-1 and PAI-2)–> inhibit t-PA
- Alpha 2-Antiplasmin—>inhibits plasmin
Def of these agents leads to bleeding!
Superficial Vein Thrombosis, when to treat
<3cm from saphenofemoral junction–>Treat with full dose x 3months
>3cm from SFJ and >5cm–> Tx with proph AC
>3cm from SFJ and <5cm–> NSAIDs and observe with serial US
*consider treatment in pregnancy and symptomatic clots
Name 4 ways in which cirrhosis leads to a prothrombotic state
decreased Protein C decreased Protein S Increased vWF increased FVIII (endothelial) Decreased portal +/- hepatic circulation leading to stasis
Name the 4 components of the prothrombinase complex
Xa
Va
Calcium
Phospholipid
Intrinsic Tenase: VIIIa, IXa, PL, Ca
Extrinsic Tenase: VIIa, TF, PL, Ca
The prothrombinase complex catalyzes the conversion of prothrombin (Factor II), an inactive zymogen, to thrombin (Factor IIa), an active serine protease
Risk of thrombosis with 1st gen, 2nd gen, 3rd gen, patch, oral HRT, progestin only?
*not sure if these are correct.
as per WHI/HER study, Oral HRT = 2 x increased risk
First and second generation risk of VTE = 3x increased risk
Third generation: 4x increased risk Higher than 2nd gen.
Patch (estrogen containing): 5x risk
Patch (progestin only): no risk
Progestin only: no risk
What single test must be done routinely to monitor all of these NOACs?
What 2 tests are most sensitive for “determining the effect of anticoagulation” in patients treated with dabigatran?
What 1 test is most sensitive for “determining the effect of anticoagulation” in patients treated with rivaroxaban or apixaban?
What feature of dabigatran accounts for its ability to be dialyzed and what percentage of this feature is present in dabigatran compared to rivaroxaban and apixaban?
- What single test must be done routinely to monitor all of these NOACs?
SCr - What 2 tests are most sensitive for “determining the effect of anticoagulation” in patients treated with dabigatran?
Ecarin clotting time. thrombin time. - What 1 test is most sensitive for “determining the effect of anticoagulation” in patients treated with rivaroxaban or apixaban?
Anti-Xa - What feature of dabigatran accounts for its ability to be dialyzed and what percentage of this feature is present in dabigatran compared to rivaroxaban and apixaban?
Apixaban and Rivaroxaban are heavily protein bound, which limits the degree to which they can be removed via IHD
Dabigatran is 80% Renally cleared (30% protein bound)
Rivaroxaban is 65% renally cleared (90% protein bound)
Apixaban is 25% renally cleared (85% protein bound)
In APLA what is the antibody that leads to the highest risk of obstetric and VTE complications
Lupus anticoagulant > anticardiolipin»_space;> anti-beta2glycoprotein
4 specific situations where you would transfuse antithrombin for a patient with congenital antithrombin deficiency
Pregnancy (with previous hx of VTE or new onset)
Surgery (cardiopulmonary surgery need of heparin)
VTE (if LMWH or if prophylactic is contraindicated)
Patient receiving asparginase
Post op for DVT proph
Name 2 causes with different mechanisms for (acquired) low protein S
Chronic Liver disease Vitamin K deficiency VKAs Acute Thrombosis Pregnancy Nephrotic Syndrome: reduced PS due to loss of free PS in the urine and an elevation in plasma C4b-binding protein concentration
Congenital (Neonatal Purpura Fulminans): AD inheritance, homozygous or double hetero
Regarding reversal agents for NOACS (direct thrombin and direct anti-Xa:
Type of molecule
Mechanism of action
Idaracizumab - a monoclonal antibody fragment, binds dabigatran with an affinity that is 350x as high as that observed with thrombin → idarucizumab binds free and thrombin-bound dabigatran and neutralizes its activity
Andexanet - recombinant, modified human factor Xa decoy protein that binds factor Xa inhibitors but does not have intrinsic catalytic activity.
Complications of APLA in pregnancy
- Pre-eclampsia
- Arterial/venous thrombosis
- Intrauterine growth restriction
- Placental insufficiency
- Pre-term delivery with prematurity complications.
*ACL alone does not have increased thrombosis risk but DOES have risk of pregnancy complications.
Name three common target antigens for autoantibodies in patients with thrombosis and APS
IgG or IgM Anti-cardiolipin antibody
IgG or IgM anti-beta2 glycoprotein I abs
phosphatidylserine, plasmin, thrombin or prothrombin.
annexin
In which patients would you not consider dose reduction of Apix/Riva according to Amplify-Extend and EINSTEIN, respectively?
- Obesity (wt>120mg)
- Needing thrombolytic with initial clot
- pHTN from PE
- Post thrombotic syndrome
- Active malignancies
Diagnostic criteria of CAPS?
- Evidence of involvement of three or more organs, systems, and/or tissues
- Development of manifestations simultaneously or in less than a week
- Confirmation by histopathology of small vessel occlusion in at least one organ or tissue
- Laboratory confirmation of the presence of antiphospholipid antibodies (lupus anticoagulant, anticardiolipin antibodies, and/or anti-beta2-glycoprotein I antibodies).
3 procedures which do not require holding Warfarin
- Cataract
- Dental procedures (can hold x 2-3 days if preference)
- Derm procedures
(Can also stay on ASA, if on DAPT hold tica or prasugrel 5-7 days before)
3 procedures in which require holding Warfarin
(i) prostate or kidney biopsy
(ii) large colonic polypectomies
(iii) cardiac pacemaker or defibrillator implantation
Homozygous or double hetero protein C deficiency, how does it present in children and what is the treatment?
- Neonatal purpura fulminans, protein C level usually undetectable
- Treat with FFP and LMWH and then transition to Warfarin indefinitely
- Protein C concentrates are approved for use in patients who have confirmed severe protein C deficiency. Generally, protein C should be administered for 6 to 8 weeks, until all lesions have healed and a therapeutic INR has been achieved. Liver transplant is curative.
What were the results of the TRIPP trial for Dalteparin in pregnant woman with history of placenta-mediated complications and thrombophilias?
Antepartum prophylactic dalteparin does not reduce the occurrence of venous thromboembolism, pregnancy loss, or placenta-mediated pregnancy complications in pregnant women with thrombophilia at high risk of these complications and is associated with an increased risk of minor bleeding.
Consequences of Warfarin in pregnancy
- Nasal hypoplasia
- Limb hypoplasia
- Stippled epiphyes (pattern of focal bone calcification.)
- Can increase bleeding in infant (consider switch to LMWH at 36 weeks)
- Dorsal midline dysplasia
- Optic atrophy
If needed for mechanical valve, give after 12 weeks. If very high risk, old mitral valve, can add ASA
Avoid at 6-12 weeks!
HIT in pregnancy, what are the preferred treatments
1st line as per ASH.
- Danaparoid
- Fondaparinox
- Argatroban
Neither cross placenta
*HIT is rare in pregnancy!