Pulmonary thromboembolism. 1. Current concepts in pathogenesis and diagnosis.

Thrombosis results from the dynamic interaction of venous stasis, hypercoagulability, and endothelial injury. Protection against thrombosis may be lost if there is deficiency of any of the factors that mediate platelet deaggregation, block fibrin deposition, or initiate fibrinolysis. A thrombus lodged in the pulmonary arterial circulation may remain hemodynamically and clinically silent or produce hemodynamic, clinical, and radiographic alterations. Although no signs and symptoms are specific to the condition, pulmonary thromboembolism can be diagnosed clinically if predisposing factors are taken into consideration. Diagnostic procedures include contrast venography, right heart catheterization, ventilation/perfusion lung scanning, and pulmonary angiography.