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surgical intervention In general these are children with unobstructed systemic blood flow and restricted pulmonary blood flow; in them the physiology results in adequate systemic DO2, a “protected” pulmonary vascular bed with normal pulmonary artery pressures, and no significant obstruction to systemic or pulmonary venous return This is most commonly seen in patients with tricuspid atresia (with atrioventricular and ventriculoarterial concordance) and a restrictive ventricular septal defect and in patients with isomerism and native obstruction to pulmonary blood flow (see Chapter 69) These patients require frequent monitoring in early infancy for adequate oxygenation as well as to confirm that pulmonary artery pressures are low; however, a small number of babies born with a fUVH may not require surgery until a planned superior cavopulmonary connection (SCPC) (see later) When Is It Safe to Leave the Operating Room? Residual lesions, inadequately palliated anatomy, is associated with increased mortality and morbidity in patients with a fUVH.102 Palliative procedures for patients with fUVH are among the most challenging procedures The patient will leave the operating room with a multidistribution rather than normal in-series circulation It is essential that the palliative procedure achieve the anatomic goal and assessment of the success of the procedure is essential prior to leaving the operating room Tools to assess the outcome of palliation will include evaluation of hemodynamics, filling pressure, blood pressure and pulse oximetry, and additional lesion-specific measures such as measurement of blood pressure in the upper and lower extremities after coarctation repair For the patients undergoing main pulmonary artery banding, in addition to assessment of hemodynamics, measurement of distal pulmonary artery pressure, echocardiography and arterial and venous oxygen saturation and pO2 may be needed Despite the relative simplicity of the procedure the systemic-to-pulmonary artery shunt is one of the higher-risk palliative procedures.103 If a shunt is too large, the patient can have excessive pulmonary blood flow at the expense of systemic blood flow.104 In addition, a shunt that is too large can result in diastolic hypotension, thus compromising coronary blood flow.104 If the shunt is too small, the patient will continue to have excessive hypoxemia Intraoperative assessment of the adequacy of a shunt is challenging The shunt is constructed in an anesthetized patient; as a consequence, VO2 is markedly reduced Saturations will be higher in the anesthetized state than when the patient is awake Assessment of the shunt is easier if the ductus is closed at the completion of the procedure For the patient undergoing placement of a systemic-to-pulmonary artery shunt, the goal is sustained relief of hypoxemia, and evaluation will include both the hemodynamics with special attention to the diastolic blood pressure as well as arterial and venous oxygen saturation and pO2 Closed palliative procedures (performed without the use of cardiopulmonary bypass)—such as coarctation repair, pulmonary artery banding, and construction of a systemic-to-pulmonary artery shunt—may be complicated by the development of a restrictive atrial septal defect The adequacy of the atrial septal defect should be evaluated preoperatively and plans for definitive management made prior to other palliative procedures The goal of Norwood palliation includes relief of systemic outflow tract obstruction, creation of a widely patent atrial septal communication, and creation of a reliable source of pulmonary blood flow that relieves hypoxemia, permits growth, but does result in heart failure Intraoperative evaluation of the patient following the Norwood procedure is challenging In addition to assessment of hemodynamics—especially blood pressure, central venous pressure and pulse oximetry—evaluation may include simultaneous measurement of ascending and descending aortic blood pressure, echocardiographic assessment of systolic function, AV valve regurgitation, size of atrial septal defect, and relief of arch hypoplasia Measurement of superior caval vein saturation, a surrogate of mixed venous saturation and NIRS, can provide information on global DO2 Identification of residual lesions such as important residual arch obstruction or a restrictive atrial septal defect should prompt the clinician to consider immediate correction The adequacy of the source of pulmonary blood flow can be more challenging Excessive hypoxemia should prompt a stepwise evaluation as outlined earlier Excessive pulmonary blood flow can be identified by higher arterial saturation and pO2, along with evidence of reduced systemic blood flow such as reduced superior caval vein saturation, reduced somatic NIRS values, and hypotension Coronary insufficiency is a major cause of mortality after the Norwood procedure Although severe coronary insufficiency is obvious—dusky, cyanotic myocardium and profoundly decreased function with inability to wean from bypass—the diagnosis of subtler coronary insufficiency is more challenging Decreased function, new AV valve regurgitation, and ECG changes are common following the Norwood procedure and can occur even in the otherwise uncomplicated patient Nevertheless, these findings should prompt evaluation of patency of the connection of the native aortic and pulmonary roots with either echocardiography or angiography Postoperative Considerations in the Neonate Neonatal surgical palliation of the patient with fUVH must provide both a systemic and pulmonary output sufficient to provide DO2 for the patient's metabolic demands and to promote healing Optimally, systemic outflow obstruction will be completely relieved and a restricted source of pulmonary blood flow will be created The source of pulmonary blood flow, although fixed to some degree, must be sufficiently large to support the infant to the secondstage palliation Even in the optimally palliated child, the early postoperative period is commonly marked by periods of decreased total output from the single ventricle; this can make achieving satisfactory DO2 challenging In addition, there is a potential for residual lesions or additional complications that affect the goal of providing adequate systemic DO2 Within this group of diagnoses and surgical reconstructions, there is proportional higher mortality than other congenital heart surgery patients The challenges of managing this group of patients has spawned the multidisciplinary CICU, which is emblematic of modern congenital heart programs These challenges are summarized in Box 71.3 Box 71.3 Key Elements of Postoperative Stabilization and Management of the Neonate With a Functionally Univentricular Heart ■ Bedside preparedness ■ Invasive monitoring ■ Bleeding ■ Delayed sternal closure ■ Assessment of adequate systemic oxygen delivery ■ Mechanical ventilation and considerations for tracheal extubation