Over the last few years, various devices for the interventional closure of atrial septal defects (ASD) up to a diameter of 20 mm have been developed. We report our clinical experience in closing ASD with a diameter larger than 20 mm diameter with the Amplatzer Septal Occluder (ASO).
Method: The stretched diameter of the ASD was measured by inflating a sizing balloon within the defect until an indentation in the circumference in the balloon could be observed. An ASO with a stent diameter 2-4 mm larger than the indentation in the circumference of the balloon was chosen and implanted via 9-12 French sheaths. In contrast to the closure of smaller defects, pullback of the device onto the atrial septum was only performed when the connecting stent of the ASO was completely deployed in order to achieve maximal centering characteristics and optimal support of the retention skirt of the left atrial disc on the edges of the defect. Only then was the right atrial disc deployed and actively configured by advancing the sheath and the delivery cable against the atrial septum. Implantation was only attempted if the atrial septal rims (except the anterior rim around the aorta) measured more than 7 mm by echocardiography to avoid injury or disturbance of sensitive intracardiac structures. After placement, the fixation of the device and the mechanical stability was proven by an extensive "Minnesota wiggle". The ASO was released only when TEE showed no or a trivial residual color flow through the connecting stent; otherwise repositioning was performed.
Results: Out of 352 patients (P) with successful closure of interatrial defects, 70 P (age: 1.1-77.3 years) had stretched defects larger than 20 mm diameter (median 22 mm diameter (20-36), 25/75% quartiles = 20/26 mm). Mean shunt size was Qp:Qs 2.1:1 (0.7-3.9:1), mean fluoroscopy time 10.9 min (0-63). Complete closure could be achieved in 85.7/93.1/100% after 3 months, 1 and 2 years, respectively. Besides 3 P with persistent atrial fibrillation, only 5 P showed transient atrial tachyarrhythmias, 2 only periprocedural and 3 within the first 3 months after implantation were treated with beta-blocker. In one patient, an acute embolization of the device occurred because a diminished posterior rim was not visualized by a monoplane TEE probe necessitating surgical explantation and defect occlusion. Despite oversizing the device, no "mushrooming" misconfiguration were observed.
Conclusion: Transcatheter closure of large atrial septal defects with the Amplatzer Septal Occluder is feasible, safe and effective. Risk of complications do not seem to occur more frequently than after closure of smaller defects if one adheres to certain sizing and implantation measures. The incidence of transient atrial tachyarrhythmias seems to be low.