Disease Information for Atrial septal defect: Definition

  • Defects in the septum between the atria of the heart, due to failure of fusion between either the septum secundum or the septum primum and the endocardial cushions-----------------------------------------------------------

    Atrial Septal Defects; ASD; Atrioseptal Defects;

    Subdivisions: Ostium Primum Defect (endocardial cushion defects included);Ostium Secundum Defect; Sinus Venosus;

    Atrial septal defects are a group of rare heart defects that are present at birth (congenital); The normal heart has four chambers with two upper chambers known as atria; They are separated from each other by a fibrous partition known as the atrial septum; The two lower chambers are known as ventricles and are separated from each other by the ventricular septum; Valves connect the atria (left and right) to their respective ventricles; A small opening between the two atria (foramen ovale) is present at birth; Shortly after birth, the atrial septum gradually closes and covers this opening; In infants with atrial septal defects, the atrial septum may not close properly or may be malformed during fetal development; In this disorder, the opening between the atria persists long after it should be closed, resulting in an increase in the workload on the right side of the heart and excessive blood flow to the lungs; Initially the symptoms associated with atrial septal defects may be absent or so mild that they may go unnoticed; Frequently this disorder is not recognized until school age or even adulthood; In adults with undetected atrial septal defects, various respiratory problems and/or heart failure may develop; There are several forms of atrial septal defects, including ostium primum atrial defects, ostium secundum defects, and coronary sinus venosus (sinus venous defect); Most cases of atrial septal defects occur for no apparent reason (sporadic); Other cases are thought to be inherited as autosomal recessive or dominant genetic traits; Atrial septal defects may also occur in association with other disorders such as Down Syndrome or Ellis van-Creveld Syndrome------------- [NORD 2005]-----