Total Anomalous Pulmonary Venous Return

Abstract

Total anomalous pulmonary venous connection (TAPVC) occurs as a result of embryologic nonunion of the left atrium (LA) and the confluence of pulmonary veins. Total anomalous pulmonary venous connection is a heterogeneous group of anatomic anomalies in which all of the pulmonary veins connect to the right atrium or its tributaries. An obligatory right-to-left shunt, usually in the atria, ensures survival by shunting blood to the left side of the heart to maintain cardiac output. Obstruction to pulmonary venous drainage occurs more commonly with certain anatomic variants that result in pulmonary edema and cardiogenic shock if not promptly treated. The anatomic types that are generally accepted and used are based on the drainage pattern of the pulmonary veins confluence. Type I or supracardiac TAPVC is characterized by drainage of the pulmonary veins confluence to a vertical vein, called the cardinal vein, which eventually drains into the brachiocephalic vein (Fig. 23.1). Another type of supracardiac TAPVC is direct drainage into the superior vena cava. Type I TAPVC is generally not obstructed unless the vertical vein is constricted by an unusual course, which can occur between the pulmonary artery and bronchus. Type II or intracardiac TAPVC is defined by pulmonary venous drainage to the coronary sinus (CS) (Fig. 23.2). This type of TAPVC is rarely obstructive except in the case of a closing patent foramen ovale (PFO). Type III or infracardiac TAPVC is characterized by pulmonary venous connection to the systemic veins by a vertical vein to the inferior vena cava or the portal vein (Fig. 23.3). These types of TAPVC are the most likely to become obstructed by the diaphragm or by the liver sinusoids through which portal vein drainage to the systemic veins must occur. Type IV TAPVC, the so-called mixed type, consists of a combination of pulmonary vein drainage; its repair represents a significant challenge.