This book explores percutaneous closure of patent foramen ovale (PFO) for the interventional and clinical cardiology communities. Specific articles address definition and pathophysiology of PFO; role of PFO in stroke; closure of PFO; echocardiographic evaluation of PFO; echocardiographic aid during PFO closure; hematologic ramifications of PFO; and history of PFO and closure devices.