Internal Diseases and Therapy · MU Sofia

11. Pulmonary embolism

Covers pulmonary embolism as a form of venous thromboembolism, from its sources and risk factors through haemodynamic and respiratory effects, then the ESC 2019 severity classes and a sign-frequency table. It goes on to Wells and Geneva scores, D-dimer use, imaging, ECG and echo findings, and a diagnostic algorithm, followed by treatment by risk class, anticoagulant dosing, thrombolysis, and duration of therapy.

Inside: 8 sections · 2 labelled pictures · 9 tables · 13 flashcards · 21 min

Topic 11 of 139 in the MU Sofia syllabus for Internal Diseases and Therapy (Medicine, Years 4 and 5). The free AceMed note covers it in 8 sections, about 2,302 words (21 min of reading), with 13 flashcards.

In this note

  1. Definition
  2. Risk factors
  3. Pathophysiology
  4. Classification
  5. Clinical presentation
  6. Diagnosis
  7. Treatment
  8. Complications and prognosis

Definition

Pulmonary embolism (PE) is the obstruction of the pulmonary arterial tree by material carried in the venous blood, in practice almost always a thrombus from the deep veins of the legs or pelvis (deep vein thrombosis, DVT). DVT and PE are two faces of one disease: venous thromboembolism (VTE).

  • About 90% of emboli come from the proximal leg veins (popliteal, femoral, iliac) and the pelvic veins. Isolated calf vein thrombi carry a lower risk of PE.
  • Upper-limb thrombosis is increasingly common, from central venous catheters, pacemaker and defibrillator leads, and can also embolise.
  • A venous thrombus can reach the systemic arteries through a patent foramen ovale or ASD: paradoxical embolism (e.g. stroke).
  • Non-thrombotic emboli (rare): fat (long-bone fractures), amniotic fluid, air, tumour cells, septic emboli (IV drug users, tricuspid endocarditis).

Risk factors

Thrombosis follows Virchow's triad: stasis, hypercoagulability and vessel wall injury.

Acquired

  • Strong: fracture of the lower limb, hip or knee replacement, major trauma, spinal cord injury, surgery in the last 4 weeks, previous VTE, active cancer (pancreas, lung, stomach, ovary, prostate, colon, brain, haematological), hospitalisation for heart failure or AF.
  • Moderate/weak: combined oral contraceptives and HRT, pregnancy/postpartum, obesity, smoking, age, COPD, arterial hypertension, prolonged sitting (travel), varicose veins, IV catheters.

Inherited (thrombophilia)

  • Factor V Leiden (resistance to activated protein C) is the most common, followed by the prothrombin G20210A mutation; both are autosomal dominant.
  • Rarer but stronger: deficiency of antithrombin, protein C or protein S.
  • Suspect thrombophilia with VTE under 50 years, recurrent or unusual-site thrombosis (cerebral, mesenteric), or a strong family history.

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