- The incidence of congenital heart defects is approximately 8 in 1000 births.1 Over the course of the past decades survival of children with congenital heart disease has improved. Today, adults can present following various cardiac surgical repairs, for routine general and obstetric anesthesia care. Unfortunately, the frequently multistaged surgical repairs necessary to improve survival in children often result in complications in adulthood. Knowledge of the anatomy of the original structural defect and the repairs undertaken is essential in the choice of appropriate monitoring and anesthetic techniques for otherwise routine procedures. Moreover, these patients may require heart surgery and/or cardiac transplantation later in life. This chapter highlights the anatomy and physiology of common congenital heart defects and outlines the repairs associated with them. In general, surgical repairs are directed at ensuring the delivery of oxygenated blood to the systemic tissues and eliminating communications between the right and left heart. Of course, for some congenital heart disease (CHD) patients the distinction of which is the right heart and which is the left heart may not be entirely clear. Consequently, when considering the CHD patient, tracing the flow of blood through the chambers of the heart into the circulation and back again provides the basis toward acquiring an understanding of CHD.
Atrial septal defects (ASD) are abnormal communications between the left (LA) and right atrium (RA). A patent foramen ovale (PFO) can be present in up to 25% of the population and produces a small interatrial communication as a consequence of failure of the septum primum and septum secundum to fuse. ASDs account for 6% to 10% of the CHD population and present in a variety of ways.2 Eighty percent of ASDs are of the ostium secundum type (Figure 12–1 and Videos 12–1A and 12–1B) located in the middle of the interatrial septum. Defects located lower in the atrial septum (toward the atrial-ventricular [AV] valves) are ostium primum ASDs and are at times associated with a ventricular septal defect (VSD) as well. Sinus venosus ASDs occur close to the junctions of the superior vena cava (SVC) or inferior vena cava (IVC) with the RA. Sinus venosus ASDs are often associated with pulmonary vein anomalies and anomalous return of oxygenated pulmonary vein blood to the right atrium.
An ostium secundum atrial septal defect is seen in this schematic (ASD) pressures and oxygen saturations in the various parts of the heart are displayed.
ASDs generally produce a left-to-right shunt of blood across the defect. Thus, oxygenated blood is delivered into the right heart circulation to be returned to the lungs through the pulmonary artery. The oxygen saturation of the RA is increased and RA and right ventricular (RV) volume ...