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Key Concepts

  • Epidemiology

    • The precise incidence of pulmonary embolism (PE) is unknown; it is estimated to be in the range of 1 to 3 in 1000 individuals. Approximately 75 percent of autopsy-proven PEs are not detected clinically. PE is particularly common in hospitalized elderly patients.

  • Pathophysiology

    • PE is usually an embolic manifestation of deep venous thrombosis (DVT), which is caused by venous stasis, vein wall injury, and hypercoagulopathy.

    • Other etiologies include malignancy, chronic indwelling central venous catheters, pacemaker leads, and spontaneous thromboses.

    • Emboli become lodged in the pulmonary artery bed and lead to pulmonary vascular hypertension by several proposed processes: redirected pulmonary blood flow, neurovascular perturbation, and hormonal changes.

  • Clinical features

    • Chronic thromboembolic pulmonary hypertension (CTEPH) presents insidiously with vague symptomatology. Suspicion should be raised when signs and symptoms for DVT (e.g., leg swelling, lower extremity venous stasis changes, chest pain, hemoptysis) are encountered.

    • The most common symptoms associated with pulmonary hypertension are exertional dyspnea, presyncope/syncope, and nonspecific chest pain or pressure.

    • The physical signs of CTEPH are related to right heart failure, including a large A wave progressing to a predominant V wave component in the jugular venous pulse. The S2 sound often is narrowly split, and P2 is accentuated; a sharp systolic ejection click may be heard over the pulmonary artery in the second intercostal space. Hypoxia/cyanosis and a right ventricular heave are observed with advanced disease.

  • Diagnostics

    • Characteristic findings on plain chest radiography are central pulmonary vascular enlargement, vascular pruning, and right ventricular enlargement.

    • Electrocardiography may demonstrate criteria for right ventricular hypertrophy, including right axis deviation and a dominant R wave in V1.

    • Pulmonary function tests usually reveal minimal changes in lung volume and ventilation with normal or slightly restricted mechanics; the diffusing capacity of the lung for carbon monoxide (DLCO) often is reduced and is the only abnormality on this test.

    • The ventilation perfusion lung scan is essential for diagnosis; an entirely normal scan excludes the diagnosis, whereas most patients with CTEPH demonstrate one or more segmental or larger perfusion defects in otherwise normal lung regions. The magnitude of perfusion defects in chronic thromboembolic disease often underestimates the actual degree of vascular obstruction. A positive scan should prompt a right heart catheterization and pulmonary angiography.

    • High-resolution computed tomography is being used more frequently in the diagnosis of pulmonary thromboembolic disease. However, the gold standard for diagnosis of CTEPH is conventional biplane pulmonary angiography.

  • Treatment

    • Medical therapy for CTEPH is limited and generally palliative. New forms of drug therapies are now available for treatment of pulmonary hypertension; however, their benefit in patients with CTEPH is very limited. Chronic anticoagulation is the mainstay of medical treatment in these patients.

    • Surgical removal of chronic thromboembolic material is the only curative option for patients with CTEPH.

  • Outcomes and prognosis

    • Pulmonary endarterectomy (PEA) is a proven procedure for the treatment of CTEPH with excellent long-term results. A 30-year experience at the University of California, San Diego (UCSD) ...

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