Andersons pediatric cardiology 1846

concordant connections (e.g., hypoplastic left heart syndrome) For these neonates there are two surgical options, Norwood palliation and so called “hybrid palliation.” The Norwood procedure includes arch reconstruction, a DKS type root amalgamation, creation of a nonrestrictive atrial septal defect, and placement of an appropriately restrictive source of pulmonary blood flow—either a modified Blalock-Taussig shunt or a shunt from the right ventricle to the pulmonary artery (Fig 71.5).89 The Norwood procedure requires cardiopulmonary bypass with a period of aortic cross-clamping and perfusion techniques that allow for aortic arch reconstruction This remains one of the higher-risk procedures commonly performed in the newborn period.90–93 FIG 71.5 (A) Norwood procedure with a systemic-to-pulmonary artery (Blalock-Taussig) shunt (B) Norwood procedure with a conduit from the right ventricle (RV) to the pulmonary artery (PA) Ao, Aorta; IVC, inferior vena cava; LPA, left pulmonary artery; PV, pulmonary vein; SVC, superior vena cava; TV, tricuspid valve (From Barron DJ, Brooks A, Stickly J, et al The Norwood procedure using a right ventricle–pulmonary artery conduit: comparison of the right-sided versus left-sided conduit position J Thorac Cardiovasc Surg 2009;138[3]:528–537.) The hybrid procedure is an alternative that provides for neonatal palliation including banding of the branch pulmonary arteries and maintenance of the arterial duct with either a stent or a prostaglandin infusion (Fig 71.6).94,95 If not present, a nonrestrictive atrial septal defect is created using interventional catheter-based techniques The advantage of the hybrid procedure is that is does not use cardiopulmonary bypass Definitive management of left ventricular outflow tract obstruction and arch hypoplasia involves a Norwood-style reconstruction combined with the second-stage procedure.96 Some programs use the hybrid procedure for all neonates with fUVH and severe arch hypoplasia This avoids a long period of cardiopulmonary bypass in the vulnerable neonate Other programs reserve this alternate strategy for patients with risk factors for cardiopulmonary bypass including; prematurity, low birth weight, infection, necrotizing enterocolitis, and intracranial hemorrhage The disadvantage of the hybrid procedure is a more challenging period between neonatal palliation and the comprehensive second-stage procedure, including the predictable need for catheter-based reintervention directed at the atrial septum or narrowing between the stented arterial duct and the more proximal aortic arch, referred to as retrograde arch obstruction.97,98 In addition, the second-stage procedure is more complicated and requires a long period of cardiopulmonary bypass for arch reconstruction and reconstruction of the banded pulmonary arteries.96 At present the decision between the Norwood procedure and the hybrid approach remains largely program-specific without an obvious advantage to either procedure in the average-risk neonate FIG 71.6 The hybrid procedure combines banding of the branch pulmonary artery and maintenance of the arterial duct This can be accomplished with a prostaglandin infusion for short-term patency or with a stent In addition, a nonrestrictive atrial septal communication must be created (From Barron DJ, Kilby MD, Davies B, et al Hypoplastic left heart syndrome Lancet 2009;374[9689]:551–564.) Surgical Technique The DKS is performed through a median sternotomy incision using cardiopulmonary bypass Patients suitable for an isolated DKS do not have arch obstruction, and profound hypothermia is not necessary After cross-clamping and cardioplegia, an anastomosis—generally with patch augmentation—is made between the great vessels above the sinotubular junction of the semilunar valves There are two general techniques In the first the pulmonary root is transected above the sinotubular junction and a vertical incision is made in the ascending aorta adjacent to the pulmonary root The adjacent proximal edges of the aorta and pulmonary root are joined, and the remainder of the connection is accomplished with a patch The second technique, sometimes called the “doublebarreled” technique, involves complete transection of both great vessels above the sinotubular junction The great vessels are joined at their “kissing” point and the ascending aorta is then anastomosed to this double-barreled root Patch augmentation is frequently required to make for the size discrepancy between the combined root and the ascending aorta A source of pulmonary blood flow is necessary In the neonate with a single left ventricle, this will be a systemic-topulmonary artery shunt In an infant that was suitably palliated with a pulmonary artery band, a bidirectional superior cavopulmonary anastomosis can be performed The Norwood procedure (Video 71.1) is performed through a median sternotomy with cardiopulmonary bypass After initial dissection, the patient is cannulated for cardiopulmonary bypass Arterial cannulation is achieved by cannulating either the pulmonary artery, arterial duct, or using an ePTFE graft anastomosed to the innominate artery Single venous or bicaval cannulation can be used for venous return Once cardiopulmonary bypass has been established, flow to the pulmonary arteries is prevented by snaring either the branch pulmonary arteries or the ductus arteriosus Three perfusion strategies have been described for the period of arch reconstruction; deep hypothermic circulatory arrest at 18°C, antegrade cerebral perfusion at deep hypothermia at 18°C to 22°C, or continuous perfusion at moderate hypothermia The last approach