Paradigm I Clinical Trial: Study of the PFX Closure System in Subjects With Cryptogenic Stroke, Transient Ischemia Attack or Paradoxical Embolism

Inclusion Criteria: * Subject is between 18 and 65 years old. * Documented patent foramen ovale as determined by positive micro bubble study demonstrating right to left shunt and/or anatomic detection and functional assessment by pre-operative TCD and peri-operative echocardiography or ultrasound. * Subjects with a history of cryptogenic stroke, transient ischemic attack or paradoxical embolism due to presumed paradoxical embolism through a PFO. * Negative pregnancy test in women who are of child-bearing potential. * Signed Informed Consent form. Exclusion Criteria: * Presence of thrombus at the intended site of closure, in left atrial appendage, or documented evidence of venous thrombus in the vessels through which access to the PFO is gained. * Active endocarditis, or other infections producing a bacteremia. * Presence of atrial septal defects or fenestrations which allow right-to-left shunting. * Presence of implanted cardiac valves, pacemaker, implantable cardioverters/defibrillators (ICDs) or vena cava filters. * Subjects with an intra-cardiac mass, tumor, clot or vegetation. * Large, redundant atrial septal aneurysm that would prohibit adequate device access to the PFO or closure of the PFO, in the judgment of the investigator. A coexisting redundant atrial septal aneurysm is considered large if it prohibits the ability of the operator to adequately achieve vacuum suction necessary to achieve PFO closure. * Presence of arrhythmia requiring pharmacologic or electrical therapy intervention or 1st degree block. * Current enrollment in any investigational trial(s) using devices implanted in the vascular system or enrolled in any experimental drug study(ies) within three months of study entry. * History of stroke or TIA within the past 14 days. * Source of stroke other than paradoxical embolization. * Hemodynamic instability or shock. * Hypercoagulable disorder. * Subjects with coagulation disorders who are unable to take antiplatelet or anticoagulant therapy.