The HELEX Septal Occluder (WL Gore and Associates, Flagstaff, AZ) device is a double-disk, nonself-centering, catheter-delivered occluder best suited for closure of small to moderate (less than or equal to 18 mm) atrial septal defects (ASDs).1 It is also used widely around the world for closure of patent foramen ovale (PFO), but is not specifically approved for this indication in the United States.2,3 The frame of the device is a single length of Nitinol wire which can be elongated over a central mandrel for catheter delivery. The frame is draped with an ultrathin expanded polytetrafluroethylene (ePTFE) membrane which is also threaded over the central mandrel (Figure 17.1).When the device is correctly configured in the heart, the central mandrel is removed and a locking loop inside of the mandrel deploys. This loop assures a slightly variable, but reasonably close, approximation of the central portions of the two functional disks. The device is very flexible and its round shape has little potential for long-term trauma to the atrial walls or the aorta. A retrieval cord provides a flexible attachment to the right atrial eyelet of the device after release from all of the other delivery components. This cord allows a measure of control for removal of the device should the configuration or position be suboptimal after release from the mandrel. Deployment of the HELEX device is an incremen-

tal process that requires more steps than most other ASD closure devices. The operator must become familiar with the basic design of the device and delivery system, and have a thorough understanding of how the major components are integrated and utilized to deliver the device. The basic steps for loading the device, and for deployment in the ASD, are outlined below, but a more detailed description and training course are available from the manufacturer.