Surgical outcomes for adults with ASD are excellent. Complications are mostly owing to perioperative arrhythmias and occasional post-pericardiotomy syndrome with effusions. Patients with elevated pulmonary hypertension, associated coronary artery disease, and ventricular dysfunction are at further risk and warrant careful assessment and appropriate combined therapy as indicated.
5.2 Surgical Closure of Superior Caval Vein Sinus Venosus Atrial Septal Defect in Association with Partial Anomalous Pulmonary Venous Return
The important factor that governs surgical closure of a superior caval vein (SCV) SV-ASD is determined by the entrance point of the right anomalous pulmonary venous return into the SCV. The more cephalad the entry of the anomalous pulmonary veins into the SCV, the more difficult the operation and higher the incidence of atrial arrhythmias owing to potential injury to the sinoatrial node.
In most patients, SV-ASD is associated with anatomic entry of the right upper and right middle pulmonary veins into the confluence of the SCV with the right atrium and ASD. Exposure is usually through a median sternotomy, with right pleural cavity entry and identification of the partial anomalous pulmonary venous return entry to the heart. The phrenic nerve is identified and preserved (Fig. 5.11). When entry of the anomalous pulmonary veins is at the SCV-right atrial junction, the surgeon can perform a simplified pericardial patch closure without augmentation of the SCV. An atrial incision can be performed away from the sinoatrial node to avoid injury to the node and preserve normal sinus rhythm. Figure 5.12 shows aortobicaval cardiopulmonary bypass, aortic cross-clamping, operative exposure, and depicts the large SV-ASD with entry of the right upper and right middle pulmonary veins into the right atrium. A small retractor reveals the os of the SCV to show the boundary between the entry of the SCV and the upper lobe pulmonary veins because the patch divides these structures for appropriate flow after the operation—that is, pulmonary venous return to the left atrium and SCV flow into the right atrium. Figure 5.13 shows the pericardial patch being used to close the SV-ASD in such a manner as to tunnel the partial anomalous pulmonary venous return flow into the left atrium, thereby appropriately dividing the systemic and pulmonary venous return. The pericardial patch is placed without redundancy to prevent stenosis of either pathway. Infrequently, sinus node dysfunction can occur and is generally related to the suture load in the right atrium, where the patch is anchored near the sinus node. Careful suture line avoidance of this area circumvents this complication (Fig. 5.14). Figure 5.15 shows the completed repair, with ghosted details to depict the appropriate and anatomic flow patterns.
5.3 Closure of Sinus Venosus Atrial Septal Defect with High Entry of the Anomalous Pulmonary Veins into the Superior Caval Vein: The Warden Procedure
The challenges of SV-ASD repair are heightened by more cephalad entry of the anomalous pulmonary veins into the SCV. Some surgeons have noted excellent results with baffling of the anomalous veins using a pericardial patch into the ASD and creating a larger systemic venous pathway for the SCV with a caval incision and another pericardial patch, the so-called two-patch technique. Surgeons who use this technique maintain that the sinoatrial node can be spared if the SCV incision and patching are performed lateral to the node, thereby ensuring unobstructed flow of both the systemic and pulmonary venous pathways. The more cephalad the pulmonary venous entry on the SCV, however, the greater the chance of obstructive and arrhythmia complications. This is the reason why the Warden procedure was introduced.
The two-patch technique has been associated with a higher incidence of sinus node dysfunction and nodal rhythm, as well as the potential and real problem of pulmonary and systemic venous pathway stenosis. To solve these problems, Warden and his colleagues offered an ingenious surgical solution to transect the SCV cephalad to the entry of the anomalous pulmonary veins and direct the flow of the anomalous pulmonary veins through the cardiac end of the caval vein into the left atrium by a pericardial patch. The right atrial appendage can then be anastomosed end-to-end to the transected SCV. The sinus node is preserved, while the systemic venous return is maintained by unobstructed flow from the SCV into the right atrium by way of the right atrial appendage. Figure 5.16 shows operative exposure through a median sternotomy in a patient with SV-ASD and high entry of the anomalous pulmonary veins. The dashed lines show the area of SCV transection and the right atrial incision for exposure and repair of the defect. The right atrial appendage is preserved for the eventual anastomosis to the SCV. Also depicted is aortobicaval cardiopulmonary bypass, aortic cross-clamping, and cardioplegic arrest. Transection of the high SCV is demonstrated (Fig. 5.17), with concomitant ligation and division of the azygous vein for extensive mobilization. The entry of the pulmonary veins into the body of the cardiac portion of the SCV is preserved.