pediatrics
Atrial Septal Defect (ASD)
Pathophysiology of ASD
To understand hemodynamic changes and review normal hemodynamic data that occur in atrial septal defect (and other anomalies), see figure. Representative right heart oxygen saturation=75%; representative left heart oxygen saturation=95%. Atrial pressures are mean pressures. AO=aorta; IVC=inferior vena cava; LA=left atrium; LV=left ventricle; PA=pulmonary artery; PV=pulmonary veins; RA=right atrium; RV=right ventricle; SVC=superior vena cava. ). Some small ASDs, often just a stretched patent foramen ovale, close spontaneously during the first few years of life. Persistent moderate to large ASDs result in large shunts, leading to right atrial and right ventricular volume overload. If unrepaired, these large shunts may lead to pulmonary artery hypertension, elevated pulmonary vascular resistance, and right ventricular hypertrophy by the time people are in their 30s or 40s. The absolute size of the defect in millimeters should not be taken in isolation, as the significance of the size of the defect varies with the age and size of the patient, and it is of lesser importance than the physiologic consequences of the degree of shunting through the defect ( Pathophysiology reference ). Atrial arrhythmias, such as Pulmonary blood flow and RA and RV volume are increased. (NOTE: Intracardiac pressures generally remain in the normal range throughout childhood.) With a large defect, RA and LA pressures are equal. AO=aorta; IVC=inferior vena cava; LA=left atrium; LV=left ventricle; PA=pulmonary artery; PV=pulmonary veins; RA=right atrium; RV=right ventricle; SVC=superior vena cava. 1.McMahon CJ, Feltes TF, Fraley JK, et al: Natural history of growth of secundum atrial septal defects and implications for transcatheter closure.Heart87(3):256-259, 2002. doi:10.1136/heart.87.3.256 