Pulmonary embolism (PE) results in at least 630,000 symptomatic episodes in the United States yearly, making it about half as common as acute myocardial infarction, and three times as common as cerebrovascular accidents.1 Acute PE is the third most common cause of death (after heart disease and cancer). Estimates of PE are probably low because approximately 75% of autopsy-proved PE are not detected clinically2 and in 70 to 80% of the patients in whom the primary cause of death was PE, premortem diagnosis was completely unsuspected.3,4 Of all hospitalized patients who develop PE, 12 to 21% die in the hospital, and another 24 to 39% die within 12 months.5-7 Thus, approximately 36 to 60% of patients who survive the initial episode live beyond 12 months, and may present later in life with a wide variety of symptoms.
In addition, approximately 2.5 million Americans develop deep vein thrombosis (DVT) each year, and more than 90% of clinically detected pulmonary emboli are associated with lower extremity DVT. However, in two-thirds of patients with DVT and PE, the DVT is asymptomatic.8-10
For the most part, DVT and acute PE are managed medically. Cardiac surgeons rarely become involved in management of acute PE, unless it is in a hospitalized patient who survives a massive embolus that causes life-threatening acute right heart failure with low cardiac output, with a large clot burden. On the other hand, the mainstay of treatment for patients with chronic pulmonary thromboembolic disease11 is the surgical removal of the disease by means of pulmonary thromboendarterectomy. Medical management for this condition is only palliative, and surgery by means of transplantation is an inappropriate use of resources with outcomes inferior to thromboendarterectomy.
Deep vein thrombosis primarily affects the veins of the lower extremity or pelvis. It is most common in hospitalized patients but may occur in ambulatory patients outside the hospital.12,13 The process may involve superficial as well as deep veins, but superficial venous thrombosis does not generally propagate beyond the saphenofemoral junction and therefore very rarely causes PE.9,14,15 Venous thrombosis of the upper extremity is almost always associated with trauma, indwelling catheters, or other pathologic states and is an uncommon cause of PE, but can be fatal. Pulmonary emboli that do not originate from the deep venous system of the legs, pelvis, or arms are thought to come from a diseased right atrium or ventricle or retroperitoneal and hepatic systems.12,13
In 1856, Rudolf Virchow made the association between DVT and PE and suggested that the causes of DVT were related to venous stasis, vein wall injury, and hypercoagulopathy. This triad of etiologic factors remains relevant today and is supported by an ever-growing body of evidence.