The diagnosis and management of pulmonary embolism.

Pulmonary embolism (PE), most commonly originating from thrombosis in the deep venous system of the lower extremities, remains a controversial area of medicine that frequently generates lively debate. Its clinical presentation varies from asymptomatic, incidentally detected pulmonary emboli to massive embolism resulting in sudden death. Despite the advances made in recent years, a number of fundamental questions remain unanswered regarding the pathogenesis, clinical presentation, diagnosis and treatment of this disease. The diagnosis of PE is confounded by a presentation that may be subtle, atypical, or obscured by a concomitant condition. Safe, minimally invasive techniques have been developed to improve the diagnostic accuracy of the clinical evaluation, and obviate the need to obtain pulmonary arteriography in all but a minority of patients. However, no single diagnostic test is sufficiently sensitive or specific for diagnosis in all patients. This dilemma has resulted in the development of numerous clinical scoring systems to stratify risk, pretest probability and help guide an appropriate diagnostic approach. Anticoagulation therapy with unfractionated heparin (UFH), low molecular weight heparin (LMWH), and Factor Xa inhibitors are the mainstay of therapy for acute PE. The choice of agent is influenced by disease severity, presence or absence of provokingfactors, patient comorbidities, and bleeding risk. These factors also determine whether measures such as thrombectomy, thrombolysis and vena cava filter placement may be employed as adjuncts to anticoagulation. Warfarin is the agent of choice for secondary prevention; newer agents such as direct thrombin and factor Xa inhibitors are emerging as safe and effective alternatives.