Contents

Atrial Septal Defect

The Amplatzer® Family of Devices

Safety

Patent Ductus Arteriosus and Muscular Ventricular Septal Defect

Eccentric Device Design

Devices Without Fabric

Summary

References

1. ATRIAL SEPTAL DEFECT 1.1. History

Atrial septal defects are congenital deficiencies in the wall separating systemic and pulmonary venous returns as they enter the heart. This allows blood from the lungs to flow through the defect and increase the volume of blood passing through the pulmonary arteries. In individuals in their 20s, living with such a defect can eventually cause permanent damage to the pulmonary vasculature. To prevent this and other problems associated with these malformations (i.e., cardiac arrhythmias), closure of atrial septal defects is recommended during the first few years of life (1).

The first successful surgical closure of an atrial septal defect was performed on a patient at the university of Minnesota Hospital in 1952 (2). Such an operative approach for correction of a congenital intracardiac defect is considered one of the safest open heart operations performed today, with a mortality rate under 0.5% (3). Nevertheless, such surgical closures are not without potential complications, including: (1) morbidity from the required sternotomy or right thoracotomy, (2) the chance of exposure to blood products, (3) utilization of a chest tube, (4) a 3- to 5-d hospitalization, (5) 4-6 weeks of convalescence, and (6) the possibility of postpericardiotomy syndrome. The opportunity to minimize or eliminate such problems has spurred attempts to develop a method of transcatheter closure.

Specifically, it is generally considered that secundum atrial septal defects are ideal for transcatheter closure. These defects are typically surrounded by rims of tissue that a device could clasp; they do not have borders formed by valves or the walls of the heart. King and Mills reported the first attempted transcatheter closure of a secundum atrial septal defect in 1976 (4). This was followed by development of the Clamshell/ CardioSEAL (5), Sideris Button (6), ASDOS (7), and Angel Wings (8) devices (Table 1). These developments were clinically exciting for they provided an alternative to surgical closure.

initially, their use also presented a number of challenges, including: (1) large devices were required with the central post design; (2) these devices were not self-centering; (3) their center posts could move within the defect; and (4) each device required large delivery systems. Furthermore, in some cases, their use was plagued by embolization (e.g., unbuttoning) (9). Unfortunately, frame fatigue and arm fracture occurred in up to 10% of some early designs, with asymptomatic wire embolization in some patients. In general, each of these designs was considered difficult to use clinically, or it was often impossible to recapture or retrieve after deployment. it was reported that surgical removal was required if they were deployed in an improper position, and residual shunt rates were significant (10).

1.2. Device Design

The ideal septal occluder device would have the following features: (1) easy delivery and implantation; (2) ability to self-

Table 1 History of Transcatheter Closure of Atrial Septal Defects

Device

Year

King and Mills

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