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and the pulmonary arteries (A) This is combined with patch augmentation of the pulmonary arteries (B) Finally, a patch is created to separate the anastomosis between the superior caval vein and the pulmonary artery from the atrium (C) (From Jonas RA The intra/extracardiac conduit Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2011;14:11–18.) For patients with nonstandard anatomy, the SCPC can be more challenging For the patient with bilateral superior caval veins, the decreased caliber of the individual caval veins makes creating a nonstenotic connection more challenging One potential advantage is the ability to perform the individual anastomoses sequentially, restoring drainage to the ipsilateral pulmonary artery before initiating the second anastomosis As a consequence the procedure can be done safely without individual cannulation of the smaller bilateral superior caval veins and, in selected cases, can even be done without cardiopulmonary bypass Nonetheless, the presence of bilateral superior caval veins increases the risk of thrombotic complications and growth of the central pulmonary arteries Bilateral superior caval veins increases the risk of both the second-stage operation and the risk of the subsequent Fontan procedure.217,218 Successful strategies include creating the anastomoses between the individual superior caval veins as centrally as possible and managing central pulmonary artery hypoplasia at the time of the completion Fontan.219 Especially among patients with left atrial isomerism, the infrahepatic vena cava may be “interrupted,” returning the superior caval vein via an azygos vein.220 Interrupted inferior caval vein with azygos continuity to a superior vena cava can occur with a single right or single left caval vein or bilateral superior caval veins In this situation a bidirectional superior cavopulmonary anastomosis, also known as a Kawashima procedure, includes all of the systemic venous return with the exception of the hepatic venous return.221 The Kawashima procedure performed in early infancy carries a higher failure rate as the immature pulmonary vascular bed is unable to accommodate the increased blood flow.222,223 As a consequence the SCPC is often delayed in patients with interrupted inferior caval veins and azygos continuation Bilateral superior caval veins occur commonly among patients with interrupted inferior caval veins, and this further increases the risk associated with second-stage palliation Decision Making: When Is It Safe to Leave the Operating Room? The ideal candidate for fUVH palliation should have good systolic and diastolic ventricular function, a competent or repairable AV valve, confluent nonstenotic or repairable branch pulmonary arteries, and sinus or paced AV rhythm The SCPC is generally a well-tolerated procedure that relieves volume work and improves hypoxemia, albeit at the expense of an elevation of central venous pressure The two most common adverse outcomes are excessive hypoxemia or an unacceptable degree of central venous pressure elevation The second-stage operation is being done at a younger age (~4 months) and even earlier progression to stage 2 is used as strategy to get patients out of the vulnerable interstage period.224 As a consequence they may not be ideal candidates and may have mildly elevated PVRs.225 Prior to weaning from bypass, recruitment and suctioning of airway secretions should be performed The lungs should have good compliance without excessive airway pressure and there should be no areas of atelectasis The typical upper body venous pressure following an uncomplicated superior cavopulmonary anastomosis is 17 mm Hg, and the transpulmonary gradient may be slightly elevated at 8 mm Hg.226 Arterial saturations are commonly in the high 70s In general these values in the young SCPC patient will improve in the first day or two following surgery Unacceptable hypoxemia, an arterial saturation less than 75%, should prompt investigation If the central venous pressure is elevated, the likely cause is obstruction to pulmonary blood flow The cavopulmonary anastomosis and branch pulmonary arteries should be carefully inspected Obstruction to pulmonary venous drainage such as a restrictive atrial septal defect with mitral atresia should be ruled out Excessive hypoxemia in the face of a normal or low central venous pressure should raise the possibility of a venovenous collateral such as a patent azygos vein or left superior vena cava that allows for shunting of blood from the superior venous compartment to the common atrium or below the diaphragm In cases of elevated central venous pressure without excessive hypoxemia, the most likely culprit is an accessory source of pulmonary blood flow such as a patent shunt, pulmonary artery, or significant aortopulmonary collateral.227 Finally, excellent hemostasis will avoid ongoing transfusion, which can adversely affect lung function Postoperative Considerations Following the Superior Cavopulmonary Connection The most recent report of the Society of Thoracic Surgeons Congenital Heart Surgery Database shows that over the last 4 years the average mortality following the SCPC was 2% and the median length of stay was 14 days.228 In the Single Ventricle Reconstruction Trial, factors associated with prolonged length of stay included center, longer post-Norwood length of stay, nonelective timing of SCPC, and pulmonary artery stenosis Mortality was 4% and was associated with nonelective timing of SCPC, moderate AV valve regurgitation, and AV valve repair.201,225,229,230 Specific postoperative considerations following the SCPC are included in Box 71.6 Box 71.6 Postoperative Considerations Following the Superior Cavopulmonary Connection ■ Bedside preparedness and invasive monitoring ■ Bleeding ■ Effects of positive-pressure ventilation and early extubation ■ Hypertension ■ Pain/irritability ■ Rhythm disturbances ■ Effusions (chylothorax) ■ Family support and discharge planning ■ Interstage II surveillance and monitoring Bedside Preparedness The principles of bedside preparedness discussed earlier following neonatal palliation are identical following a SCPC—specifically environmental and staff preparedness (see Box 71.3) These include communication with the operating room and anesthesia team regarding the intraoperative course, bleeding, vasoactive agents, and echocardiographic findings Specifically following the SCPC, there are physiologic benefits of early extubation, and these should be discussed between the team in the operating room and team in the intensive care