Longembolie

Longembolie, also known as pulmonary embolism, is a blockage of the pulmonary arteries or their branches by an embolus that travels to the lungs. Most emboli are thrombi that originate in the deep veins of the legs or pelvis, a condition known as deep vein thrombosis. Less commonly, emboli can be fat, air, septic material, or tumor fragments.

The obstruction causes ventilation–perfusion mismatch and impaired gas exchange, which can lead to hypoxemia and, in large emboli, right ventricular strain or failure. Symptoms range from sudden shortness of breath and pleuritic chest pain to coughing up blood or fainting; some cases are asymptomatic, especially when the embolus is small. The presentation depends on the size and location of the blockage and on cardiovascular reserve.

Risk factors include prolonged immobilization, recent surgery or fracture, cancer, pregnancy, estrogen-containing contraception or hormone therapy, obesity, smoking, inherited thrombophilias, and a history of venous thromboembolism. The condition often arises after a preceding deep vein thrombosis, but can occur without identifiable injury.

Diagnosis relies on clinical suspicion supported by tests. D-dimer testing is helpful in low–to–moderate risk patients. CT pulmonary angiography is the preferred imaging test in most settings. When CT is unavailable or contraindicated, ventilation–perfusion scanning can be used. Ultrasound of the legs can detect coexisting DVT, and ECG or echocardiography may assess cardiac strain.

Treatment depends on risk stratification. Anticoagulation is the mainstay (unfractionated heparin, low–molecular-weight heparin, or direct oral anticoagulants). Thrombolysis or surgical embolectomy is considered for massive PE with shock or instability. Supportive care and oxygen therapy are important, and preventive measures include DVT prophylaxis in high-risk individuals.

Prognosis varies with embolus size, comorbidities, and promptness of treatment. Prevention focuses on reducing venous thromboembolism risk through mobility, pharmacologic prophylaxis after major surgery, and mechanical methods when appropriate.