An update on ASD occlusion devices

A trial septal defects (ASDs) are one of the most common congenital heart defects, with a prevalence estimated to affect 100 of 100,000 live births.1 ASDs are classified according to location, the most frequent being secundum ASD (75%–80%), primum ASD (15%–20%), sinus venosus (5%–10%), and the less common defect, coronary sinus (< 1%). These defects frequently result in left-to-right shunting. Current indications for closure, according to American and European guidelines, are a ratio of pulmonary over systemic flow > 1.5 and enlargement of the right-sided chambers with or without symptoms, in the absence of significant pulmonary hypertension (class I). Closure may also be reasonable in the setting of paradoxical embolism or documented orthodeoxia-platypnea syndrome (class IIa). Closure may also be considered if the pulmonary vascular resistance is less than two-thirds of the systemic resistance or if the pulmonary arterial pressure is less than two-thirds of the systemic pressure at baseline or responsive to pulmonary vasodilators (class IIb) (Table 1).2,3 Transcatheter closure of ASDs has progressed because of the development of the first stainless steel devices covered by Dacron,4 and is now the gold standard for the treatment of secundum ASDs. Patients with defects amenable to transcatheter closure can be divided into simple secundum defects (< 26 mm in diameter) and more complex secundum ASDs, which are larger and may have concomitant rim deficiency.5 Patients with defects > 40 mm, or those with multiple deficient rims or coexistent pulmonary venous anomalies, are usually referred for surgical closure. The procedure is most often performed under transesophageal echocardiographic guidance to evaluate the septal anatomy, size the defect using “stop-flow,” and to confirm device position and the presence of residual shunt. Intracardiac echocardiography can also be used but may have some limitations in the setting of large or complex defects with rim deficiency.6,7 Balloon sizing of the ASD is an important step to provide information of the stretched diameter, the compliance of the septum, and the presence of other previously unrecognized defects. In the case of pulmonary hypertension, evaluation of pulmonary pressure during balloon occlusion can provide additional information on the presence of undiagnosed Eisenmenger syndrome. We will discuss the most commonly used and newer available devices for the transcatheter closure of ASDs, as well as recent device developments in this field.