Percutaneous closure of patent foramen ovale (PFO) and ASD is performed using a special closure device. The device is folded or attached to a special catheter, similar to the catheter used during your catheterization. The special catheter is inserted into a vein in the leg and advanced into the heart and through the hole. The device is slowly pushed out of the special catheter allowing each side of the device to open up and cover each side of the hole, closing the hole or defect. When the device is in proper position, it is released from the special catheter. Over time, heart tissue grows over the implant, becoming part of the heart. The PFO and ASD closure procedure is monitored by X-ray and ultrasound. Different types of closure devices are used to close a hole or an opening between the right and left sides of the heart. Some of these birth defects are located in the wall (septum) between the upper chambers (atria) of the heart.