Professor of Neurology and Director of the Comprehensive Stroke Center at the Hospital of the University of Pennsylvania. He is also the leading investigator for the REDUCE trial, a prospective, randomized, multicenter, multinational trial designed to demonstrate safety and effectiveness of the GORE Helex Septal Occluder (W.L. Gore, Flagstaff, AZ) for PFO closure in patients with a history of cryptogenic stroke or imaging-confirmed transient ischemic attack (TIA). The study includes up to 50 investigational sites in the United States and Europe.