Atrioventricular septal defects are common congenital heart defects affecting the interatrial and interventricular septa as well as the atrioventricular valves. Atrioventricular septal defects occur due to the failure of endocardial cushions to properly develop and migrate to septate the heart during embryonic development; therefore they are also referred to as endocardial cushion defects. There are three common types or descriptions for atrioventricular septal defects: partial, transitional, and complete. An ostium primum type atrial septal defect exists in all types of atrioventricular septal defects. Partial and transitional atrioventricular septal defects have similar physiologic implications and are often diagnosed later in life as left-to-right shunting is not as significant; patients with complete atrioventricular septal defects have more significant left-to-right shunting with more severe pulmonary overcirculation, usually necessitating earlier intervention. This chapter discusses the pertinent findings and perioperative management of a patient with an unrepaired transitional atrioventricular septal defect.

An atrioventricular septal defect is a defect in the center of the heart consisting of a common atrioventricular valve, a primum atrial septal defect, and an inlet ventricular septal defect. When the common valve is not positioned equally over both ventricles it is called an unbalanced atrioventricular septal defect. This unbalance leads to a decreased inflow of blood to one of the ventricles, and that ventricle and outflow tract are often hypoplastic. The degree of unbalance can vary widely, ranging from mild, which in effect is similar to a large ventricular septal defect, to severe, which can often involve a hypoplastic ventricle and dependence on a patent ductus arteriosus to provide adequate flow to the affected circulation. This chapter discusses the anesthetic management of a 1-day-old patient with trisomy 21 and an unrepaired, unbalanced atrioventricular septal defect undergoing a laparoscopic repair of duodenal atresia. Anesthetic concerns regarding patients with trisomy 21, physiologic changes with laparoscopic surgery and implications of an unbalanced atrioventricular septal defect are all examined in detail.