This issue of Interventional Cardiology Clinics, edited by the series Editor-in-Chief, Dr. Matthew Price, will cover Transcatheter Closure of Patent Foramen Ovale. Some of the topics discussed in this issue include, but are not limited to, PFO and the Interatrial Septum: Clinical-Anatomic Correlations; Current Dataset for PFO Closure in Cryptogenic; Stroke: Randomized Clinical Trials and Observational Studies; PFO closure: Devices and Technique; Identification and quantification of PFO-mediated shunts: echocardiography and transcranial Doppler; PFO closure for Hypoxemia; and Imaging Assessment of the interatrial Septum for ASD and PFO closure, among others.