In this video, Dr. Radha Krishnan, Director, Pediatric Cardiologist at Fortis Escorts Heart Institute, New Delhi, will explain how to differentiate patent foramen ovale (PFO) from atrial septal defect (ASD). This differentiation is generally by echocardiography. When a flap is seen overlapping each other then it is known as a PFO. When the flap separates crating a clear defect, it is called an ASD. Dr. Radha Krishnan will talk on stretch PFO which can become an atrial septal defect. And it becomes difficult to differentiate between them and needs to be detected by echocardiography. He will also discuss the differentiating features between a PFO and ASD.