Background: The heart is the main source of arterial emboli (> 80%). The majority of remaining sources are arterioarterial or of unknown origin, with each accounting for 5% to 10% of cases. This study covers an 8-year period and analyzes the etiology of arterial emboli of the extremities, with emphasis on patients with paradoxical emboli.
Methods: The hospital records of all patients were reviewed, with emphasis on patients with paradoxical emboli. The sources of emboli were classified as cardiac, arterioarterial, paradoxical emboli (fulfilled Johnson's criteria triad with cardiac defect and right-to-left shunting), possible paradoxical emboli (met two of Johnson's criteria), or unknown.
Results: This series included a total of 406 cases, and the sources of emboli were as follows: 248 (61%) cardiac, 62 (15%) arterioarterial, 6 (2%) paradoxical emboli, 8 (2%) possible paradoxical emboli, and 82 (20%) had an unknown source or incomplete work-up. The mean age of paradoxical emboli patients was 39 years, in contrast to a mean of 68 years for the entire series. All 6 paradoxical emboli patients presented with acute ischemia of an extremity, symptoms of deep vein thrombosis or pulmonary embolism or both, and a documented patent foramen ovale with right-to-left shunting. None of the patients had evidence of cardiac or peripheral atherosclerotic disease. Their treatment included one or more of the following: embolectomy, lytic therapy, anticoagulation, caval filters, or closure of a patent foramen ovale.
Conclusions: Paradoxical emboli should be considered when the source of emboli is unknown, particularly in young patients. A complete work-up on these patients should include contrast saline or transesophageal echocardiography, lung scan, and peripheral venous imaging, particularly if conventional echocardiography and arteriography did not lead to a diagnosis.