Infracardiac TAPVC

Anatomy
- Patients with infracardiac TAPVC have a vertical confluence that drains via vertical vein that crosses the diaphragm and most often enters the portal sinus, but rarely can connect with the IVC or a hepatic vein. Anatomic obstruction of the pathway is uncommon but can occur as the vertical vein passes through the diaphragm or at the junction with the portal sinus; veins which drain to the portal vein are are almost always obstructed as soon as the ductus venosus closes since pulmonary venous return must pass through hepatic sinusoids to return to the RA as shown. In these patients, placement of a UVC into the RA via the ductus venosus may worsen pulmonary venous hypertension and should be avoided/removed. In cases of severe pulmonary vein obstruction, native pulmonary veins may be hypoplastic or even atretic.

Pathophysiology
- Infradiaphragmatic TAPVC often causes pulmonary venous hypertension due to downstream obstruction, creating pulmonary edema, respiratory insufficiency, and hypoxemia (due to low Qp [right to left arterial shunting] in the setting of open PDA as well as due to pulmonary edema). Treatment relies on respiratory support (often intubation and ventilation), correct diagnosis (ensuring the anatomy of all pulmonary veins is important), and urgent surgical repair. In some cases, infradiaphragmatic veins do not create a phenotype of severe obstruction and can be semi-electively repaired.

Repair of Infracardiac TAPVC

Postoperative considerations
- Was there preoperative clinical pulmonary vein obstruction?
  - If so, the ventilator course may be prolonged. Anticipate diuresis, several days of mechanical ventilation, and possible postextubation respiratory support.
- Pulmonary vein obstruction also causes reactive pulmonary hypertension that can persist post-repair. Monitoring for RV hypertension (tachycardia, elevated CVP, narrow pulse pressure) and treating it (inotropic support, keeping lungs open, iNO) are important, particularly if the ASD was closed without fenestration.
- In the early postoperative period, bleeding may sometimes cause tamponade physiology (narrow pulse pressure, elevated LAP) as thrombus may accumulate and compress the LA and may require re-exploration. Some patients may return with open sternum, particularly if bleeding or concern for pulmonary hypertension is significant.
- In some patients cross-clamp time may be prolonged; monitor for low cardiac output.