SM_258b: Thrombotic Disorders

Question 1

Venous thrombosis is ___

Answer 1

Venous thrombosis is an occlusive clot in a vein

• DVT is blood clot in veins in legs / arms
• Pulmonary embolus: migrating thrombosis (clot) that travels to pulmonary artery, often embolizes from DVT of leg
• Superficial veins of arms and legs: superficial vein thrombosis, superficial thrombophlebitis
• Other locations

Question 2

Describe rates of embolism from DVT to PE

Answer 2

Rates of embolism from DVT to PE

• Proximal lower extremity DVT: 50%
• Distal lower extremity DVT: 10-15%
• Upper extremity DVT: 6-10%

Question 3

In erect position, blood is propelled ____, while backflow is prevented by an extensive system of ____

Answer 3

In erect position, blood is propelled proximally from calf veins by muscular action, while backflow is prevented by an extensive system of valves

Question 4

While valves prevent blood pooling distally, there is ___

Answer 4

While valves prevent blood pooling distally, there is increased turbidity within the valve sinus potentially stimulating thrombus formation

• Procoagulant factors: vWF
• Anticoagulant factors: endothelial protein C receptor (EPCR), thrombomodulin (TM)

Question 5

Proximal DVT is proximal to the ___

Answer 5

Proximal DVT is proximal to the popliteal vein

Question 6

Describe VTE nomenclature

Answer 6

VTE nomenclature

• Temporal pattern: based on symptoms and imaging characteristics, acute (immediate to days), subacute (weeks), chronic
• Anatomic location: PE (saddle, lobar, segmental, subsegmental), VTE of extemities (superficial vs deep, deep is proximal vs distal)

Question 7

Describe categories of PE

Answer 7

PE categories

• Massive: hemodynamically unstable: shock
• Submassive: associated right ventricular strain without hemodynamic instability
  
  • Signs of RV strain: RV systolic dysfunction or RV dilation on echo, RV/LV > 0.9 or flattening of septum or paradoxical spetal bowing on CT scan, elevated BNP and troponin

Question 8

DVT usually presents with ___, ___, ___, and ___

Answer 8

DVT usually presents with pain, unilateral swelling, warmth, and redness

Question 9

PE presents with ____ and ____

Answer 9

PE presents with dyspnea and pleuritic chest pain

Question 10

Describe Wells criteria for DVT and PE

Answer 10

Wells criteria for DVT and PE

Question 11

Plasma D-dimer is a ___

Answer 11

Plasma D-dimer is a cross-linked fibrin degradation product that increases up to 8-fold in VTE

• Non-specific: also increases with age, pregnancy, renal failure, and malignancy
• Used in conjunction with pre-test probability in diagnostic workup

Question 12

Describe lab / imaging diagnosis of DVT / PE

Answer 12

Lab / imaging diagnosis of DVT / PE

• DVT: D-dimer, Duplex US, venography, MRI
• PE: D-dimer, CTA, pulmonary angiography
• V/Q scan, echo

Question 13

Describe compression US for DVT

Answer 13

Compression US for DVT

• Venous pressure rises when vein is occluded by thrombus and becomes incompressible
• Echogenic material within lumen may suggest presence of thrombus
• Good for thrombi in common femoral, superficial, and popliteal veins
• Not as good for thrombi in distal veins of calf and pelvic veins

Question 14

___ is gold standard for diagnosis of PE

Answer 14

Pulmonary angiogram is gold standard for diagnosis of PE

Question 15

30 yo woman with Hx of anxiety presents to ER with concern of RLE swelling that has progressed over past 2 weeks, which started day after returning from driving home for Florida. Taking OCPs.

Wells score is ___

Then, get ____

D-dimer is 700 so get ____

Answer 15

30 yo woman with Hx of anxiety presents to ER with concern of RLE swelling that has progressed over past 2 weeks, which started day after returning from driving home for Florida. Taking OCPs.

Wells score is 2 (intermediate)

Then, get D-dimer

D-dimer is 700 so get RLE US Doppler

Question 16

Incidence of VTE increases with ___

Answer 16

Incidence of VTE increases with age

• Blacks more likely to die

Question 17

Virchow’s triad is ___, ___, and ___

Answer 17

Virchow’s triad is endothelial injury, abnormal blood flow, and hypercoagulability

Question 18

Threshold model of VTE is ___

Answer 18

Threshold model of VTE is risk increases above a threshold with inherited or acquired risk factors

• Inherited thrombophilia
• Acquired risk factors: advanced age, obesity, cancer, immobility
• Triggering factors: surgery, pregnancy, hormonal therapy

Question 19

Trousseau’s syndrome is ___

Answer 19

Trousseau’s syndrome is thrombophlebitis migrans may be a sign of abdominal cancer

Question 20

Describe mechanism of cancer-related VTE

Answer 20

Cancer-related VTE mechanism

• Tissue factor is expressed by tumor
• Tumor release of procoagulants
• Tumor compression of vessels

Question 21

Tumor types with highest risk of VTE are ____, ____, ____, and ____

Answer 21

Tumor types with highest risk of VTE are primary brain, pancreatic, stomach, and lung cancer

• Tumor type is associated with risk of VTE

Question 22

Thrombophlebitis, recurrent thrombus, and thrombi in unusual locations may indicate ___

Answer 22

Thrombophlebitis, recurrent thrombus, and thrombi in unusual locations may indicate cancer-related VTE

Question 23

May-Thurner syndrome is ___

Answer 23

May-Thurner syndrome is chronic compression of the L common iliac vein between the overlying R common iliac artery and first vertebral body

• Associated with VTE

Question 24

Venous thoracic outlet syndrome (Paget-Schroetter syndrome) is ___

Answer 24

Venous thoracic outlet syndrome (Paget-Schroetter syndrome) is axillary-subclavian DVT associated with strenuous or repetitive activity

Question 25

VTE is treated with ___ and ___

Answer 25

VTE is treated with anticoagulation and thrombolysis

• Anticoagulation: balance risk of VTE and risk of bleeding, duration of anticoagulation depends on risk factors for clot
• Thrombolytic therapy: systemic thrombolysis, catheter-directed thrombolysis, thrombectomy

Question 26

IVC filter indications are ___

Answer 26

IVC filter indications are acute PE or proximal DVT and inability to use therapeutic anticoagulation

• Potential complications: acute clot (PE, DVT), distal obstruction, perforation, embolization

Question 27

Complications of VTE are ___, ___, ___, and ___

Answer 27

Complications of VTE are death, recurrent thrombosis, post-thrombotic syndrome, and pulmonary hypertension (CTEPH)

• Risk of recurrence greatest closer to event, higher in men

Question 28

Post-thrombotic syndrome is when ____, leading to ____ and ____

Answer 28

Post-thrombotic syndrome is when venous occlusion by thrombi increase venous pressure (venous hypertension) and result in venous distension, leading to incompetent valves and reflux

Question 29

Describe consequences of post-thrombotic syndrome

Answer 29

Post-thrombotic syndrome consequences

• Symptoms of pain, paresthesia, sensation of heaviness, residual swelling
• Signs of chronic venous insufficiency: discoloration of leg, ulcers, dilated veins
• Can result in permanent disability
• No good treatment options

Question 30

Chronic thromboembolic pulmonary hypertension is when ___

Answer 30

Chronic thromboembolic pulmonary hypertension is when pulmonary vasculature becomes attenuated due to vessel wall thickening and luminal narrowing

• Risk factors: younger age, previous PE, large perfusion defects, idiopathic presentation

Question 31

Chronic thromboembolic pulmonary hypertension presents with ____, ____, ____, and ____

Answer 31

Chronic thromboembolic pulmonary hypertension presents with dyspnea, fatigue, anorexia, and hemoptysis

Question 32

Chronic thromboembolic pulmonary hypertension treatment involves ____ and ____

Answer 32

Chronic thromboembolic pulmonary hypertension treatment involves chronic anticoagulation and thromboendarterectomy in severe cases

Question 33

Describe VTE prevention

Answer 33

VTE prevention

• During hospitalization: mobility, mechanical, pharmagoloci thromboprophylaxis
• Extended thromboprophylaxis