Annex A > Chapter 3 - Developments in the UK, in the Diagnosis and Treatment of Congenital Heart Abnormalities in Children, 1984-1995 > The specific heart abnormalities and procedures referred to in the Inquiry > Atrial Septal Defect (ASD)

Atrial Septal Defect (ASD)

Figure 3: Atrial Septal Defect

The problem

41 There is a defect or hole in the wall (septum) between the two upper chambers of the heart, the left and right atriums. The hole might occur in any part of the atrial septum. The common defect is the one illustrated, known as a secundum ASD. In the presence of an abnormal hole, blood flows along the path of least resistance. Normally the resistance to flow is much lower in the blood vessels to the lungs than in those to the body. Therefore, in an ASD, blood flows from the left atrium to the right atrium, so that a larger volume of blood than normal then flows into the right ventricle and to the lungs. The chambers of the right side of the heart become `volume loaded' but it is rare for heart failure to develop during infancy or early childhood.

Diagnosis

42 The diagnosis has been made reliably by echocardiography since the early 1980s. The advances in technology have served to enhance the precision and accuracy of demonstrating the site and nature of the defect. It is rare for the cardiologist to need to resort to cardiac catheterisation.

Management

43 It is recommended that the defect should be closed during childhood in order to prevent problems in adolescence or early adult life. During the period of the Inquiry's Terms of Reference, an ASD would be closed by means of an open-heart operation but since the mid-1990s technology has evolved to allow just over a third of these defects to be closed by means of cardiac catheter devices. Throughout the 1980s and onwards, the risk of undertaking open-heart surgery in order to close an ASD has generally been regarded as very low.

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