VTE

VTE

blood clot in vein

DVT

blood clot in deep vein (extremities)

PE

blood clot in lungs

Virchow’s triad

• blood stasis

• vessel damage

• hypercoagulable state

Stasis risk

• AFib

• LV dysfunction

• Immobility/paralysis

• venous insufficiency, varicose veins

• venous obstruction from tumour, obesity, pregnancy

Vascular wall injury risk

• trauma/surgery

• venepuncture

• chemical irritation

• heart valve disease or replacement

• atherosclerosis

• indwelling catheters

Hypercoagulable risk factors

• malignancy

• pregnancy, peri-partum

• oestrogen therapy

• trauma/surgery of lower extremity, hip, abdomen, pelvis

• IBS

• nephrotic syndrome

• sepsis

• thrombophilia

Risk factors

• recent surgery

• limited physical movement

• history of stroke, MI, HF, paralysis

• broken bones

• cancer

• blood circulation issues

• persona/family history of clots

• hormones (birthcontrol, HRT)

• obesity

• 60+

• smoking

• implanted vascular access

• previous thromboembolism

• anti-phosphlipid syndrome

Bleeding Risk scales

• IMRPOVE (increase risk 7+)

• HAS-BLED

DVT S/SX

• unilateral swelling

• warmth, redness

• pain (worse when standing/walking)

PE S/SX

• difficulty breathing

• SOB

• chest pain (worse w deep breath)

• coughing (may cough blood)

• rapid HR

• fainting/dizziness

Diagnosis

• clinical assessment

• elevated D-dimer (byproduct of fibrin degradation, not diagnostic by itself)

• diagnostic studies 

  • DVT → venography, ultrasound

  • PE → pulmonary angiography

Complications

• postthrombotic syndrome

• chronic thromboembolic pulmonary HTN

IPC devices

• non-pharm primary prevention

• deliver sustained pressure distal → proximal

• only beneficial if used for 18+ H/day

• PCD: uniformly inflated

• SCD: graded sequential pressure (pref)

• CI: severe PVD, open wounds/infection on limb, active DVT within 6 mo, immobilized for 72+H, post-operative vein ligation, limb deformitites, recent skin graft, dermatitis

TED stockings

• non-pharm prophylaxis

• improves blood flow, decrease sweeling

• apply mild pressure to prevent blood from clotting in patients with limited mobility

Long travel considerations

• non-pharm pref for VTE porphylaxis

• hydrate, avoid alc

• ambulate

• aisle seat

• calf exercises

• compression stockings (below knee)

• exception → notable VTE risk, previous VTE

Atheroembolism and warfarin

• purple toe syndrome

• cholesterol embolization syndrome

• multiple small emboli move to hands and feet → obstruct small arteries

• occurs within first 3-8 weeks of therapy

Dabigatran counseling points

• keep. inoriginal container

• bottle is only good for 4 months after opening

• swallow whole with full glass of water

CHEST guidelines for VTE prophylaxis

• medical illness → LMWH, UFH, fondaparinux

• surgical → LMWH, UFH (controverisal aspirin in 2020 guidelines)

American Society of Hematology 2019 surgical prophylaxis guidelines

• hip/knee → aspirin or anticoag

  • pref DOAC > LMWH > UFH>warfarin

• major → LMWH, UFH

Provoked, transient precipitating factor

• surgery or nonsurgical transient risk factor

• surgery, cast, hosptialization, trauma

• 3 months of therapy

Provoked, persistent precipitating factor

• cancer, antiphospholipid syndrome, thrombophilia (factor V leiden, antithrombin III deficiency, Protein C or S deficiency)

• extended therapy

Unprovoked (idiopathic) precipitating factor

• extended therapy if low bleeding risk

• 3 months if high bleed risk

Cancer pt VTE treatment

Oral Xa inhibitor > LMWH for initation/treatment

Initiation phase

• 0-21 days

• initial anticoags (mostly parenteral)

Treatment Phase

• 3 months

• mostly oral (DOAC pref over warfarin EXCEPT in antiphospholipid syndrome)

Extended Phase

• 3+ months (no planned stop date)

• secondary prevention

• reduced dose apixaban/rivaroxaban > full dose pref

IVC Filter

• Non-pharm

• secondary prevention

• limited role for when anticoags contraindicated

• captures embolism on its way to heart/lungs and allows blood flow around trapped clots

PE with hypotension (SBP <90 for 15 min) tx

thrombolytic therapy

Pref in pregnancy

UFH, LMWH

Pref in peds

UFH, warfarin

Pref in cancer

Factor Xa inhibitors > LMWH

Pref in renal failure

UFH, warfarin, apixaban

Holding Anticoags before surgery

• UFH: hold 6-8H

• LMWH: hold 24H

• apixaban/edoxaban: hold 2 days prior

• warfarin: hold 5 days prior

Switching from warfarin to DOAC

stop warfarin and start new agent when INR < 2

Thrombolytic therapy

• not required for most patients

• eligible patients → high risk pts without htn, massive PE with evidence of hemodynamic compromise

• PE → alteplase

• systemic pref (peripheral vein) over catheter directed

Surgical removal

• thrombectomy

• embolectomy (reserved for massive PE)

HIT

• Heparin induced thrombocytopenia

• drop in platelet levels

• HIT II → immune-mediated reaction in first 5-10 days after starting heparin/LMWH

  • potential for thrombosis, ischemic limb necrosis, MI, stroke

HIT pathophys

• heparin/LWMH binds to platelet factor 4

• IgG from complex activates platelets

• platelets release pro-thrombotic substances

• platelets drop, removed by macrophages

4T Risk Assessment

• Thrombocytopenia (50%)

• Timing of platelet count fall (5-10 days)

• Thrombosis

• other causes for thrombocytopenia

• 4+ → concern for HIT

HIT diagnosis

• first → 4T scoring

• Assay testing

  • ELISA (risk false +)

  • SRA (gold standard)

HIT Tx

• goal: reduce thrombosis risk

• stop all forms of heparin

• stop warfarin and reverse with vitamin K (risk of microthombosis)

• begin alt anticoag at tx dosing

  • IV direct thrombin inhibitors: Argatroban (pref in renal), Bivalirudin (pref in liver)

  • SC Xa inhibitor: Fondaparinux

  • vitamin K antagonist if platelets are over 150 to reduce microthrombosis risk

• duration: min platelet recovery (150+), max 3 months

HIT recovery

• begins within 1-2 days of stopping offending agent

• antibodies may persist for years → do NOT use heparin agents in pt with HIT