Atrial septal defect types

Congenital heart disease (CHD) occurs in approximately 25 000 births per year in the United States. An atrial septal defect (ASD) is a spedfic form of CHD and is the third most common type of defect. Many people suffer from this disorder and in many cases it is only detected when the patient reaches middle age. Effective and efficient methods of repair are therefore needed to minimize the risks associated with traditional methods of ASD repair. In recent years, transcatheter closure methods for secundum type ASD have been developed. Currently the Amplatzer Septal Occluder, the Gore Helex Septal Occluder and the NMT Medical CardioSEAL-STARFiex Septal Occlusion systems have received FDA approval for ASD repair, the first of these only in 2001. This indicates that the use of these devices is still in its infancy. It can therefore be assumed that much more can be done to develop improved and more effective closure devices. It is the purpose of this chapter to describe ASDs and to outline the available technology with regard to transcatheter ASD repair devices. Hie discussion will centre around their construction and functioning, with special reference to their textile component. 

Masura J, Gavora P and Podnar T. Long-term outcome of transcatheter secundum-type atrial septal defect closure using amplatzer septal occluders. J Am Coll Cardiol 2005 2/15 45(4) 505-507. 

The valves are straightforward and are often implemented as ideal diodes (for electrical circuit models) or as IF-THEN-ELSE statements (for algorithmic models) to keep all flows nonnegative. Defects in the valves can be added to simulate heart defects (e.g., leaky diodes for regurgitation). Other types of heart defects are just as easily simulated. For example, Blackstone et al. [1976] placed an impedance between the atrial chambers to simulate a septal opening. 

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