One should review all previous data related to the patient and the defect to be closed and ensure that appropriate devices and delivery systems are available. Aspirin 81–325 mg should be started 48 h prior to the procedure. Alternatively, clopidogrel 75 mg could be used.

The procedure is performed under either transesophageal echocardiography (TEE) or intracardiac echocardiography (ICE) guidance. If TEE is used, due to the length of the procedure and for patient’s comfort, the procedure should be done under general endotracheal anesthesia. If the procedure is performed under ICE guidance, mild sedation is given. The procedure is most often performed via femoral venous access. Heparin is administered to maintain an activated clotting time (ACT) above 200 s at the time of device deployment. Broad spectrum antibiotic administration is recommended for the procedure (eg. cefazolin 1 g iv), the first dose at the time of the procedure and two additional doses 6–8 h apart. Right heart catheterization is performed to measure pulmonary artery pressure, calculate pulmonary vascular resistance and shunt (Qp:Qs) ratio. The pulmonary vascular reactivity can be evaluated if necessary. TEE or ICE (Figs. 32.2 and 32.3) images are obtained to assess the ASD anatomy (location, size, additional defects and rims) [3]. It is important to fully evaluate the atrial septal anatomy as well as that of adjacent structures to ensure that the device will be properly seated following deployment.

The angiographic catheter is advanced into the left atrium from the inferior vena cava into the right upper pulmonary vein. An angiogram is then performed (Fig. 32.4a) to evaluate the atrial septal length and shape. A stiff guide wire is advanced just distal to the catheter tip (Fig. 32.4b). The angiographic catheter is exchanged for a sizing balloon (Fig. 32.4c). The balloon is placed across the defect under fluoroscopic and echocardiographic guidance and then inflated with diluted contrast until the left-to-right shunt ceases as observed by color flow Doppler on TEE or ICE. The indentations in the balloon made by the margins of the ASD are measured on echocardiographic or fluoroscopic images (Fig. 32.4c). Usually the echo measurements are more reliable than the fluoroscopic measurements. A device approximately 1–2 mm larger than the measured sizing balloon diameter is selected. The sizing balloon is removed and a delivery sheath is advanced over the super stiff guide wire to the left upper pulmonary vein (Figs. 32.4d and 32.5b). Extreme care must be exercised to not allow passage of air inside the delivery sheath.