although occasionally the orientation is better with anastomosis to the underside of the arch FIG 36.20 Surgical technique for creation of an end-to-side aortopulmonary connection (aortopulmonary window, Melbourne shunt) (A) The main pulmonary artery is divided as proximally as possible and spatulated with a longitudinal incision (B) A partial-occluding aortic clamp is applied to the aorta, usually to the postero-leftward aspect (C) The aortotomy is performed and the anastomotic site is enlarged by excising a button of aortic tissue, and the anastomosis is performed with continuous 7-0 monofilament absorbable suture The optimal location for anastomosis varies according to anatomic variables, including both pulmonary artery anatomy and aortic size and position (D) In most cases, a left posterolateral anastomosis just above the sinotubular junction is performed, but if the lie of the pulmonary artery is better, the anastomosis is to the underside of the aortic arch (E) (From Rodefeld MD, Reddy VM, Thompson LD, et al Surgical creation of aortopulmonary window in selected patients with pulmonary atresia with poorly developed aortopulmonary collaterals and hypoplastic pulmonary arteries J Thorac Cardiovasc Surg 2002;123:1147–1154.) Anesthetic Considerations There are a number of important anesthetic considerations in patients with TOF/PA/MAPCAs undergoing unifocalization Aside from patients with extreme cyanosis or congestive heart failure, inhaled induction with sevoflurane is appropriate in most circumstances The fraction of inspired oxygen used during induction and maintenance should vary according to the degree of preoperative pulmonary blood flow, typically to maintain an oxygen saturation of 75% to 85% The anesthesiologist should be prepared for a difficult intubation, particularly in patients with a chromosome 22q11 deletion, who may have airway anomalies55,57; however, mask ventilation can usually be performed without compromise.61 Prior to initiating cardiopulmonary bypass, it is important to maintain adequate systemic perfusion pressure to avoid systemic acidosis, hypoxemia in patients with tortuous and stenotic MAPCAs, and coronary hypoperfusion in patients with high pulmonary blood flow (i.e., due to extensive runoff through MAPCAs) For this reason, volatile agents—which decrease blood pressure, systemic vascular resistance, and cardiac output—typically are not used after induction, and a total intravenous anesthetic technique is employed In some instances, hypoxemia due to ligation of MAPCAs, along with ongoing blood loss, can result in significant metabolic acidosis Administration of bicarbonate and maintenance of an adequate hematocrit for oxygen-carrying capacity are important in such cases The use of a low-dose inotrope, such as dopamine 3 to 5 µg/kg per minute, improves cardiac output and supports arterial blood pressure during the dissection and ligation period In separating from cardiopulmonary bypass, we typically use dopamine at 5 µg/kg per minute, milrinone at 0.5 µg/kg per minute, and low-dose epinephrine for inotropic support More recently the empiric use of inhaled nitric oxide has been instituted to decrease the pressure imposed on the newly anastomosed pulmonary vessels Blood loss may be significant due to prolonged dissection, ligation of numerous MAPCAs, extensive suture lines, single or bilateral pulmonary arterial augmentation, placement of a right ventricle–to-pulmonary artery conduit, and closure of a ventricular septal defect Historically the routine use of antifibrinolytics, such as aminocaproic acid, was avoided in these patients due to concerns about thrombosis in the newly anastomosed vessels However, our current perspective is that thrombosis is of less concern relative to the risk of significant bleeding with redo sternotomy.62 Standard blood management at our institution generally includes 0.5 to 1 unit of packed red blood cells prior to cardiopulmonary bypass; 2 to 4 units of packed cells and 2 to 3 units of fresh frozen plasma on bypass; and 1 to 2 units of packed cells, 2 to 4 units of cryoprecipitate, and 1 to 3 units of platelets after bypass We typically give at least the first platelet unit as a plasma-reduced unit to maximize the number of functional platelets given in the smallest volume The prompt administration of protamine in conjunction with cryoprecipitate and platelets is imperative to achieve rapid hemostasis We have recently used FEIBA (Baxalta US), a fourfactor prothrombin complex concentrate, at a dose of 10 U/kg, which has proven to be beneficial in reducing blood product administration and in achieving prompt hemostasis, thus limiting the use of blood products Postoperative Management The postoperative cardiac physiology after unifocalization surgery depends in part on whether complete repair (with closure of ventricular septal defect) was performed Children undergoing single-stage unifocalization and repair have normal oxygen saturations without intracardiac mixing postoperatively They return to the cardiac intensive care unit with left atrial and right ventricular intracardiac lines for close hemodynamic monitoring Although cardiopulmonary bypass times can be prolonged in children undergoing extensive pulmonary artery reconstruction, the aortic cross-clamp times are usually relatively short and the low cardiac output expected after surgery is mild.63 With our approach, nearly all patients have systolic pulmonary artery pressures less than half systemic after repair, and most have pressures equal to or less than 40 mm Hg.42 This has important implications for the postoperative course, as right ventricular pressures remain low and right ventricular dysfunction is rare Respiratory failure in the postoperative period is multifactorial To achieve the lowest pulmonary artery pressure possible, surgical dissection into the segmental level of the lungs is often necessary to enlarge the peripheral pulmonary