Transcatheter closure of ostium secundum atrial septum defect (ASDII) using the new self-centering occluder, Amplatzer Septal Occluder (ASO), has been well developed in recent years. We describe the importance and role of transesophageal echocardiography (TEE) in the selection and closure of such defects. Methods: Thirty patients referred for transcatheter closure of ASDII by ASO were enrolled in this study. During catheterization, two-dimensional TEE was performed on all patients during and

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... er transcatheter closure. ASD size and morphology were assessed by TEE before catheterization. The ASD stretched diameter was also measured by TEE and fluoroscopy. Results: With the aid of TEE, transcatheter closure of an ASD was successfully, safely and effectively performed on 29 patients. The mean ASD diameter determined by TEE was 17.4 4.8 mm. The mean stretched diameters measured by TEE and fluoroscopy were 18.7 5.6 mm and 17.9 5.5 mm, respectively. The mean device diameter was 19 5.6 mm. Immediate complete closure was documented by color Doppler TEE in 29 patients. Complications were encountered in one patient, with the device becoming dislodged into the main pulmonary artery. The device was retrieved by surgery and the defect was repaired in the operating room. Conclusions: Transcatheter closure of ASDs using an Amplatzer device is feasible, safe and effective. Two-dimensional TEE can provide useful information before, during and after transcatheter closure of ASDs. (Chang Gung Med J 2005;28:837-45)