Thrombosis

Question 1

RF for thrombosis in children

Answer 1

• Central line - Cancer - surgery - Sepsis/unwell child - trauma/immobility - obesity - estrogen - dehydration - anti-phosphiolipid syndrome - chronic disease (cardiac, rheum, IBD)

Question 2

RF for ARTERIAL clots

Answer 2

AIS - cardiogenic - vasculopathy (moyamoya) - in situ thrombosis (unwell child with iron def, hyperhomocystenemia) Catheter - umbilical, femoral Perinatal stroke

Question 3

What types of thrombosis are you at risk for with estrogen based OCP

Answer 3

VTE stroke MI 4-fold increase in risk. Note absolute risk is low so most have additional RF

Question 4

Initial labs for patient with new clot

Answer 4

CBC INR/PTT fibrinogen Creatinine d-dimer and FVIII - not specific but if elevated and persistent, then predictive of poor outcome

Question 5

Describe May Thurner syndrome

Answer 5

Right iliac artery crosses over left iliac vein - chronic narrowing of vein

Question 6

When to evaluate for hypercoagulable state

Answer 6

• non CVL thrombosis - Recurrent thrombosis - Contraception councelling in adolescent with strong family history

Question 7

Hypercoag workup

Answer 7

• APC resistance (FVL, Prothrombin gene mutation) - Protein C - Protein S - AT - Hyperhomocystenemia - Elevated FVIII - lipoprotein a - dysfibrinogenemia - PAI-1 def - Anti-phospholipid antibodies

Question 8

Factor V Leiden key points

Answer 8

Mechanism: APC resistance - 95% heterozygotes never have VTE - 4x increased risk for hetero, - 80x for homozygotes. –> Absolute risk is tiny for children - no risk of arterial clots

Question 9

Which severe thrombophilia is notable for pregnancy-related VTE

Answer 9

anti-thrombin deficiency (heterozygous)

Question 10

Neonate with pulpura fulminans

Answer 10

Protein C/S deficiency (homozygous) Manage: aggressive FFP Q12h, lifelong anti-coagulation

Question 11

Age-related changes in Protein C/S and AT

Answer 11

• all low as neonate - Protein S at adult level at 6-12 m - Protein C remains low till late teens

Question 12

Anti-phospholipid syndrome diagnosis

Answer 12

Clinical (at least 1): - venous or arterial thrombosis - recurrent preg loss < 10 wk GA, or prem < 34 wks due to pre-eclampsia/placental insuff Lab criteria (at least 1): - Persistent LA, ACL, or B2Glycoprotein antibody for > 12wks with context of acute thrombosis Catastrophic APS - 3 or more clots in 1 week.

Question 13

Heparin mechanism of action

Answer 13

Binds AT and increases activity by 1000x - inactivated thrombin and FXa

Question 14

Name anticoag & mech of action other than heparin/LMWH/warfarin

Answer 14

Xa inhibitors: - Fondaparinux (IV) - Danaparoid (IV) - Rivaroxaban (oral) - Apixaban (oral) - Edoxaban (oral) Thrombin inhibitor: - Argatroban (IV) - Bivilarudin (IV) - Dabigatran (oral)

Question 15

Reasons for heparin resistance

Answer 15

• using PTT rather than Xa (false resistance) –> high fibrinogen/FVIII in inflammation will normalize PTT even if Xa is therapeutic - AT deficiency (cong or acquired ex. asparaginase) - Increased clearance (Lasix, CVH) - Increased heparin binding proteins

Question 16

HIT diagnosis

Answer 16

4T score - Thrombocytopenia (usually > 20) - Timing of fall (5-10 d or <1d if prev exposure) - Thrombosis - no oTher cause Ab against PF-4

Question 17

HIT diagnosis

Answer 17

Switch empirically given super high risk of thrombosis - send ELISA for circulating Ab - confirm with functional serotonin release assay

Question 18

Anti-Xa level false results

Answer 18

• hemolysis - hyperbili - hyperTG * not affected by age or coagulopathy

Question 19

Indications for fibrinolysis

Answer 19

• Limb threatening arterial thrombosis - Intracardiac - Massive/submassive PE - Extensive DVT –>SVC syndrome, occlusive IVC, Bilat renal vein, large iliofemoral

Question 20

Contraindications for thrombolysis

Answer 20

• active bleeding
• significant potential for local bleeding (ex. tumor surrounding vessel with clot)
• general surgery or LP within the previous 10 days, neurosurgery within the previous 3 weeks
• hypertension
• AV malformations
• recent severe head trauma