The delivery system of GSO is designed to optimize control and precise device implantation. Furthermore, it also allows for complete device retrieval after device lock release. The system consists of a delivery catheter, a control catheter and a mandrel coupled to a handle (Fig. 17.4). The GSO device is preloaded onto a 10 Fr delivery catheter without the need for a large-diameter long catheter making it simple to operate, reducing the risk of air- or thrombo-embolism and allowing smaller patients to be treated. In order to ease passage of the system across the septal defect, it is compatible with 0.035″ guide wire using monorail technique and in this case a short 11 Fr venous introducer is needed. It is pre-curved with 75 cm working length with a radiopaque marker band at the distal end.

The GSO device comes in sizes of 15, 20, 25 and 30 mm (Fig. 17.5). As for HSO, the optimal size selected for the defect is recommended to be at least a 2:1 ratio, and there must be adequate space to accommodate the device within the atrial chambers, as well as adequate tissue rim to prevent device prolapse and embolization.

The GSO device is packed ready to load (Fig. 17.6). The first step of device preparation is to remove the Packaging Insert (Fig. 17.7). The system should be flushed with heparinized saline prior to and after loading. Next, the device is loaded into the sheath by moving the Loading and Deployment Slider away and to the right (Figs. 17.8 and 17.9 with red arrow)

The GSO delivery system has simplified the device deployment process, ensuring consistency in the deployment process thus reducing the effect of inter- and intra-operator variability in skill and technique. The delivery catheter has a monorail design (Fig. 17.10). While the delivery catheter is entering into an 11 Fr femoral venous sheath, flushing should be continued. It is then advanced into the left atrium via a guide wire, e.g. Amplatz Super Stiff Guidewire (Boston Scientific), which is positioned in the left upper pulmonary vein.

Once in the left atrium, the guide wire is removed. The left disc is deployed by moving the Loading and Deployment Slider to the left (Fig. 17.11 top). The slider will stop when the mandrel is fully extended. Next, the Loading and Deployment Slider is pushed away from the operator and then further left to a mid position (Fig. 17.11 bottom) and the flat left disc will be formed when the left and central eyelets are adjacent to each other fluoroscopically. When the left disc is well formed, the delivery system should be pulled back until the disc is at the septum.

Once the left disc is at the septum under echocardiographic guidance, the right disc is deployed by moving the Loading and Deployment Slider further left and then towards user (Fig. 17.12). The device formation is complete and both discs should be in ‘cup-shape’ fluoroscopically. This shape indicates the tension over two discs is well balanced. Moreover, three eyelets should be in close proximity not more than 10 mm apart.

If the position of the device is not optimal, it could be re-sheathed and repositioned. The steps of re-sheath are the same as the device loading (Figs. 17.8 and 17.9). When the position of device is considered to be optimal, it should then be locked. To lock the device, the handle should be held in a neutral position by right hand, and all tension should be released from the atrial septum (Fig. 17.13 top). At the same time, the lock mechanism should be squeezed on both sides of handle by left hand and moved to right until it stops (Fig. 17.13 bottom). This maneuver makes the locking loop capture all three eyelets, and the device should be seen locked on fluoroscopy. The device could be released by fixing the handle, flipping up the red retrieval cord lock, and then pulling the retrieval cord removing suture in its entirety (Fig. 17.14).