Cardiovascular · Year 1 · from Cardiovascular
Case 1: Deep Vein Thrombosis - Virchow's Triad in Action
Patient Presentation
Demographics: 58-year-old female
Chief Complaint: Left leg swelling and pain for 3 days
History of Present Illness: A 58-year-old female presents with progressive swelling and pain in her left calf over the past 3 days. She reports that the discomfort started after returning from an 8-hour transatlantic flight 5 days ago. She describes a dull, aching pain that worsens with walking and when standing. She notes that her left calf appears larger than the right. She has a history of breast cancer treated with tamoxifen for the past 2 years.
Physical Examination:
- Vital Signs: BP 128/78 mmHg, HR 88 bpm, RR 16/min, SpO2 98% on room air, Temp 37.2C
- General: Mild distress due to leg discomfort
- Left Lower Extremity:
- Calf circumference 4 cm greater than right
- Pitting edema to mid-calf
- Warmth and erythema over posterior calf
- Tenderness along deep venous distribution
- Positive Homans sign (calf pain with dorsiflexion)
- Right Lower Extremity: Normal
Workup
- Wells Score for DVT: 3 points (active cancer +1, calf swelling >3cm +1, pitting edema +1) - Moderate probability
- D-dimer: 1.8 mcg/mL (elevated, normal <0.5)
- Compression Ultrasonography:
- Non-compressible left popliteal vein
- Echogenic material within vein lumen
- Absent color Doppler flow
- Left femoral vein also involved
- Labs:
- CBC: WBC 8.2, Hgb 12.4, Plt 245
- PT/INR: 12.1 sec / 1.0
- aPTT: 28 sec
Diagnosis
Acute proximal deep vein thrombosis of the left lower extremity (femoral and popliteal veins)
Hemostasis and Thrombosis Correlation:
Virchow's Triad Analysis:
- Stasis:
- 8-hour flight with prolonged immobility
- Venous pooling in dependent lower extremities
- Stagnant blood allows coagulation factor accumulation
- Prevents dilution and clearance of activated factors
- Endothelial Injury:
- Prolonged venous distension damages endothelium
- Loss of antithrombotic endothelial surface
- Exposure of subendothelial tissue factor
- Release of von Willebrand factor
- Hypercoagulability:
- Active malignancy (breast cancer)
- Tamoxifen therapy (estrogen-like effects)
- Cancer produces procoagulant factors
- Tissue factor expression by tumor cells
Why D-dimer is elevated:
- D-dimer is a fibrin degradation product
- Indicates active fibrinolysis of cross-linked fibrin
- High sensitivity but low specificity for DVT
- Negative D-dimer excludes DVT in low-probability patients
Coagulation Cascade Activation:
- Tissue factor exposure initiates extrinsic pathway
- Factor VII activation leads to factor X activation
- Thrombin generation converts fibrinogen to fibrin
- Factor XIII cross-links fibrin (stable clot)
- Plasmin gradually degrades fibrin (produces D-dimer)
Why proximal DVT is concerning:
- Higher risk of embolization to pulmonary circulation
- Large thrombus burden
- Greater risk of post-thrombotic syndrome
Treatment
- Anticoagulation (immediate):
- Rivaroxaban 15 mg BID for 21 days, then 20 mg daily
- Alternative: Enoxaparin bridge to warfarin (INR goal 2-3)
- Duration: Extended anticoagulation (cancer-associated)
- LMWH or DOAC preferred over warfarin in malignancy
- Compression stockings: 30-40 mmHg for post-thrombotic syndrome prevention
- Activity: Early ambulation with anticoagulation
- Monitor for PE symptoms: Dyspnea, chest pain, tachycardia
- Cancer follow-up: Continue surveillance
Clinical Image
Image Description: Clinical photograph showing unilateral left lower extremity swelling consistent with deep vein thrombosis. Note the visible edema and increased circumference of the affected leg compared to the contralateral limb.
Source: Wikimedia Commons - Deep vein thrombosis of the right leg License: CC BY-SA 4.0 URL: https://commons.wikimedia.org/wiki/File:Deep_vein_thrombosis_of_the_right_leg.jpg