Infracardiac Total Anomalous Pulmonary Venous Return (TAPVR)
Overview and natural history
Total anomalous pulmonary venous return (TAPVR) is a rare congenital malformation in which all four pulmonary veins do not connect normally to the left atrium. Instead, the four pulmonary veins drain abnormally to the right atrium by way of an anomalous venous connection. There are four main types: supracardiac, intracardiac, infracardiac or mixed venous drainage.
Infracardiac TAPVR is a subtype of TAPVR in which the pulmonary veins connect via the umbilicovitelline system. The pulmonary veins drain to a confluence which in turn drains inferiorly, most commonly via a descending vertical vein which descends anterior to the esophagus through the diaphragm into the portal venous system (most common), ductus venosus, hepatic veins or IVC. This subtype of TAPVR can result in pulmonary venous obstruction as the descending vertical vein drains within the portal venous system. Obstruction may be secondary to multiple etiologies which include intrinsic narrowing of the connecting vessel, the interposition of the hepatic sinusoids between the pulmonary veins and the heart and constriction of the ductus venosus. An atrial septal defect is necessary to allow pulmonary venous return to reach the left heart and systemic circulation.
Early atresia of the common pulmonary vein while pulmonary-systemic venous connections are still present
Depends on whether obstructed or unobstructed. If pulmonary veins are unobstructed behaves like a large ASD (left to right shunt). With obstruction, patient may manifest tachypnea and feeding difficulties in the first few days or weeks of life. Severe obstruction causes decreased pulmonary blood flow with worsening cyanosis