(BQ) Part 2 book "Moss & adams heart disease in infants, children, and adolescents" presentation of content: Congenital cardiovascular malformations; diseases of the endocardium, myocardium, and pericardium, pulmonary vascular disease, the young adult with congenital heart disease, other special problems and issues. | SECTION VI PART A CHAPTER 28 Congenital Cardiovascular Malformations Septal Defects Atrial Septal Defects Ritu Sachdeva INTRODUCTION Atrial septal defects (ASD) originate at particular sites in the atrial septum and are named according to their embryonic origin. The most common occurs in the central part of the atrial septum in the region of fossa ovalis (secundum ASD). Others include those in the region of endocardial cushion (primum ASD), in the sinus venosus septum (sinus venosus ASD), and in the region of ostium of coronary sinus (coronary sinus ASD). In this chapter, we also address patent foramen ovale (PFO), which is a normal interatrial communication present in fetal life that may persist in adults. Ostium primum ASD is discussed in Chapter 29 since it is a part of the spectrum of atrioventricular septal defects (AVSD). INCIDENCE ASDs constitute 8% to 10% of congenital heart defects in children. The incidence of ASDs has been estimated to be 56 per 100,000 live births (1). The recent estimates are much higher (100 per 100,000 live births), likely due to increased recognition of ASDs in this era of the common use of echocardiography (2). The female:male ratio for secundum ASDs is 2:1, but for the sinus venosus ASDs it is 1:1 (3,4). Secundum ASDs constitute approximately 75% of ASDs, followed by ostium primum ASD (20%) and sinus venosus ASD (5%) (5). Coronary sinus (CS) ASDs more often are seen in association with heterotaxy syndromes and systemic venous anomalies, and isolated CS ASDs are rare (<1%). GENETIC AND ENVIRONMENTAL RISK FACTORS Although most ASDs occur sporadically, familial modes of inheritance have been reported. The risk of congenital heart disease in offspring of a woman with a sporadic ASD is estimated to be 8% to 10% (6). ASDs may be related to mutations in either regulatory genes or their target sarcomeric genes. Heterozygous mutations in the transcription factor CSX were among the first found in families with .
