Venous Thromboembolism

Venous Thromboembolism - Clot Chaos Intro

• VTE: Pathological clot formation in veins. Spectrum: Deep Vein Thrombosis (DVT) - common in legs; Pulmonary Embolism (PE) - clot travels to lungs.
• Pathophysiology: Virchow's Triad 📌 (SHE):
  • Stasis (e.g., immobility, post-op)
  • Hypercoagulability (e.g., Factor V Leiden, malignancy, OCPs)
  • Endothelial injury (e.g., trauma, central lines)
• Classification:
  • Provoked: Due to transient risk factor (surgery, trauma).
  • Unprovoked: Idiopathic; higher recurrence risk.

⭐ Factor V Leiden is the most common inherited thrombophilia predisposing to VTE.

Venous Thromboembolism - Leg Clot Alert

• Deep Vein Thrombosis (DVT): Common, serious VTE manifestation.
• Clinical Signs: Unilateral leg swelling, pain, warmth, erythema. (Homan's sign: low sensitivity/specificity).
• Wells Score: Stratifies DVT risk (Low/Mod/High). Key factors include: cancer, paralysis, recent surgery/immobilization, tenderness, leg swelling, edema.
  • Score ≥2: DVT likely.
  • Score <2: DVT unlikely.
• Diagnosis:
  • Compression Ultrasonography (CUS): Gold standard. Non-compressible vein = DVT.
  • D-dimer: High NPV; useful to exclude DVT in low probability cases.

⭐ Paradoxical Embolism: DVT can cause stroke via patent foramen ovale (PFO).

Venous Thromboembolism - Lung Clot Crisis

Pulmonary Embolism (PE): Lung artery obstruction, often from DVT. Symptoms: Sudden dyspnea, pleuritic pain, tachypnea, tachycardia. Massive PE: hypotension (SBP < 90 mmHg), syncope. Diagnosis: - Wells/Geneva Score: Pre-test probability. - D-dimer: Rules out PE if low probability. - CTPA: Gold standard imaging. - V/Q Scan: If CTPA C/I. - ECG: S1Q3T3 (classic), sinus tachycardia. Management: - Anticoagulation: LMWH, UFH, DOACs. - Thrombolysis/Embolectomy: For massive PE (hemodynamic instability). - IVC Filter: Recurrent PE or anticoagulation C/I.

⭐ Westermark sign (oligemia) & Hampton's hump (pleural-based infarct) are classic but rare CXR findings in PE.

Venous Thromboembolism - Clot Busters & Blockers

• Primary Goals: Prevent clot propagation, embolization (PE), recurrence; restore flow.

• Therapeutic Pillars: Anticoagulation (blockers), Thrombolysis (busters).

• Anticoagulants (Clot Blockers):

  • Initial: LMWH (Enoxaparin 1 mg/kg BID), UFH, Fondaparinux.
  • Long-term: DOACs (Apixaban, Rivaroxaban) strongly preferred.
  • Warfarin: Target INR 2.0-3.0; requires bridging & monitoring. 📌 Mnemonic: WEPT (Warfarin Extrinsic PT).

• Thrombolytics (Clot Busters):

  • Indications: Massive PE (SBP <90 mmHg, persistent instability), extensive limb-threatening DVT (phlegmasia).
  • Agents: Alteplase (tPA). Catheter-directed thrombolysis (CDT) for selected cases.

• IVC Filters:

  • Reserved for: Absolute contraindication to anticoagulation; recurrent PE despite adequate anticoagulation.

⭐ DOACs are first-line long-term for most VTE over Warfarin: superior safety/efficacy, no INR checks. Exceptions: Antiphospholipid syndrome, severe renal failure.

Venous Thromboembolism - Guarding the Gates

• Prophylaxis: Mechanical (GCS, IPC); Pharmacological (LMWH, UFH).
• Pregnancy:
  • LMWH preferred throughout & 6 weeks postpartum.
  • Warfarin contraindicated (teratogenic).
• Cancer-Associated Thrombosis (CAT):
  • LMWH or DOACs for long-term treatment.
• Long-term: Duration individualized; DOACs often used.

⭐ LMWH is the anticoagulant of choice for VTE in pregnant patients.

High‑Yield Points - ⚡ Biggest Takeaways

• Virchow's triad (stasis, hypercoagulability, endothelial injury) is key to VTE pathogenesis.
• Wells score and D-dimer are crucial for DVT/PE diagnosis and risk stratification.
• Pulmonary Embolism (PE) is a life-threatening complication of DVT.
• Anticoagulation (LMWH, UFH, DOACs) is the mainstay of VTE treatment.
• IVC filters are indicated for recurrent VTE despite anticoagulation or when anticoagulation is contraindicated.
• Post-thrombotic syndrome (PTS) is a common long-term complication of DVT.
• Massive PE may require thrombolysis or embolectomy; Saddle embolus is a classic example of massive PE affecting the pulmonary artery bifurcation.