Paradoxical embolism after cardiac catheterization

Paradoxical embolism is seen in fewer than 2% of all arterial emboli. It occurs most often through a patent foramen ovale (PFO), which is present in up to one-third of patients with strokes of unknown etiology. We report a 69-year-old woman in whom a thrombus traveled from the lower extremity venous system to her right middle cerebral artery through an unsuspected atrial septal defect. Following right femoral artery catheterization for coronary angiography, she developed a femoral artery pseudoaneurysm and groin hematoma causing compression of the right femoral vein and venous thrombosis. Before she could undergo surgical evacuation and repair, she developed a right brain stroke with cognitive deficits, left field cut, left hemiparesis, and sensory loss. Transthoracic echocardiography with bubble contrast showed a small PFO with right-to-left interatrial shunting. A Greenfield filter was placed in the inferior vena cava, and the patient was anticoagulated before she underwent inpatient rehabilitation. This case illustrates the importance of considering paradoxical emboli in unexplained strokes. The literature is reviewed, and treatment and prevention of paradoxical emboli are discussed.