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Anomalous pulmonary venous drainage occurs when the pulmonary veins drain into systemic veins or into the right atrium rather than the left atrium. The anomalous pulmonary venous drainage can be total, involving all of the pulmonary venous return, or partial, involving some of the pulmonary venous return. High SVC partial anomalous pulmonary venous drainage refers to drainage of some or all of the right sided pulmonary veins to the SVC remote from the right atrium. This abnormality results in left-to-right shunting of blood at the atrial level, as well as right ventricular and right atrial dilatation. With prolonged dilatation, right ventricular dysfunction and atrial arrhythmias can occur. In addition, long standing pulmonary overcirculation occurring as a result of this anomaly can eventually lead to pulmonary vascular obstructive disease.
Repair of high SVC partial anomalous pulmonary venous return requires cardiopulmonary bypass and aortic cross-clamping. The conventional approach to repair of this lesion is similar to the technique of repair described for sinus venosus atrial septal defect, in which the anomalous pulmonary venous drainage is redirected with a patch through an atrial septal defect into the left atrium (see Sinus Venosus Atrial Septal Defect). A patch or baffle placed in the superior vena cava, however, could potentially result in obstruction of the superior vena cava or the anomalous pulmonary vein. With an alternative technique, the SVC is divided just above the entrance of
the anomalous pulmonary vein. Next, the lower SVC stump is oversewn, and the entire mouth of the SVC is redirected with an intracardiac baffle through an atrial septal defect created by the surgeon. The upper SVC is then sewn to the right atrial appendage to allow upper body systemic venous return to enter the right atrium (see diagram). With this technique, the potential for SVC obstruction due to scarring around the intra-caval baffle is avoided. In addition, postoperative atrial arrhythmias are minimized since suture lines are remote from the area of the SA node. Aortic cross clamp time and cardiopulmonary bypass time required to repair this defect are usually short to moderate.
The postoperative course following repair of high SVC partial anomalous pulmonary venous drainage is usually benign. Invasive monitors used include central venous and arterial catheters. Non-invasive monitors include NIRS (near-infrared spectroscopy) probes to assess adequacy of regional and global perfusion and traditional pulse oximetry. Vasoactive infusions required for hemodynamic management are rarely required. Atrial arrhythmias are a potential complication following this repair. Temporary cardiac pacing capability should be readily available. Stenosis of the SVC-right atrial connection is a rare complication, but it would likely manifest itself as swelling of the head and upper body. Bleeding is an unusual complication since suture lines are exposed to low right heart pressure. Length of hospital stay required for recovery averages 4 to 6 days.