Atrial Septal Defects and Cardioembolic Strokes.

Atrial septal defects (ASDs) can be complicated by cardioembolic strokes, but the exact incidence is unknown. Patients with large and small shunts may present with a cardioembolic stroke. Patients with cryptogenic strokes should have cardiac ultrasound to see if an ASD is present. Cardioembolic strokes associated with ASD principally occur with 2 mechanisms. The first is paradoxic embolism involving a venous-based source of thrombus, which may subsequently pass through the ASD by right-to-left shunting, causing a cardioembolic stroke. The second is atrial fibrillation that can complicate the course of patients with ASDs, especially as they age.