Introduction: Evaluation and Management TOF/PA is an uncommon and highly variable form of congenital heart disease, both anatomically, as discussed earlier, and clinically The most severe forms of this condition include pulmonary blood supply through major systemic-topulmonary (aortopulmonary) collateral arteries (TOF/PA/MAPCAs) As with all duct-dependent lesions, patients with TOF/PA and pulmonary blood flow exclusively through an arterial duct require early initiation of prostaglandins In patients with TOF/PA/MAPCAs, in which pulmonary blood flow is not completely duct-dependent, prostaglandin therapy is not necessary but long-term survival is nevertheless poor without treatment, with 10-year and 20-year survival estimated at 50% and 20%, respectively.11,12 As detailed earlier, the primary source of complexity and heterogeneity in patients with TOF/PA is the pulmonary arterial circulation.13,14 The extent and variability of abnormalities in the pulmonary circulation, along with the relative rarity of the condition, pose considerable challenges for evaluation and management A number of investigators have described approaches to treatment for TOF with MAPCAs, but most series have been relatively small, have reported only short-term outcomes, and the results have been mixed.15–36 Approximately 25 years ago, our group developed a management protocol aimed at optimally addressing all of the morphologic and physiologic variants of this lesion with the goal of achieving complete repair in as many patients as possible and with pulmonary artery pressures as close to normal as possible Important components of this approach include early surgical unifocalization independent of symptom status, incorporation of blood supply to all lung segments in the unifocalization process, utilization of native tissues for pulmonary arterial reconstruction whenever possible, and relief of pulmonary arterial obstructions out to the segmental level The early experience with this approach was first described in 1995,37 and the initial 6-year experience was reported in 2000.38 Additional studies from our group have focused on the refinement of this strategy or specific issues or subpopulations within this cohort.39–45 Some groups have adopted this approach16,17,22,26,35,36 while others continue to utilize approaches developed prior to 1992, which are often staged and utilize a variety of techniques, including placement of systemic-to-pulmonary arterial shunts or right ventricle-to-pulmonary artery conduits, catheter-based angioplasty or stenting, and different techniques of unifocalization that are often partial or staged Although there is some debate about surgical strategies, in this chapter we will focus on our approach to the management of TOF/PA/MAPCAs Diagnosis and Evaluation In the current era, most patients with TOF/PA are diagnosed prenatally or early in life.46,47 Clinically, distinguishing TOF/PA/MAPCAs from TOF/PA or truncus arteriosus depends primarily on the morphology of the central pulmonary arteries, presence of a patent ductus arteriosus, and the detection of MAPCAs Neonatal presentation can vary depending on the amount of pulmonary blood flow and the degree of cyanosis, if any, but it typically consists of cyanosis with a murmur, often a continuous murmur best heard in the peripheral chest produced by flow through MAPCAs Some patients without cyanosis initially manifest symptoms of pulmonary overcirculation and congestion Rarely, patients may present at months or years of age with progressive cyanosis Imaging evaluation includes standard transthoracic echocardiography as well as modalities that provide more detailed information about the pulmonary blood supply, such as catheterization angiography, computed tomography, and in some situations magnetic resonance imaging Echocardiography Transthoracic echocardiography demonstrates the usual findings of TOF/PA, with a large ventricular septal defect and an overriding aorta (Fig 36.10) In patients with TOF/PA but no MAPCAs, echocardiography is usually sufficient for preintervention evaluation In patients with TOF/PA/MAPCAs, central pulmonary arteries may or may not be visualized by echocardiography, and MAPCAs arising from the descending aorta are typically seen but not fully characterized In the small subset of patients with a sole supply of one branch pulmonary artery through a ductus arteriosus or anomalous pulmonary artery from the ascending aorta, echocardiography can be diagnostic Otherwise, however, echocardiography does not provide detailed information regarding the anatomy of MAPCAs In patients with confluent central pulmonary arteries, it has been reported that the size of the central pulmonary arteries on echocardiography can help to differentiate patients with TOF/PA who do and do not have important MAPCAs,48 although this association generally does not guide evaluation Thus, in order to characterize the anatomy of the pulmonary circulation completely in patients with MAPCAs, another imaging modality is required FIG 36.10 Echocardiographic images demonstrating typical intracardiac anatomy in patients with tetralogy of Fallot/pulmonary atresia/major aortopulmonary collateral arteries from the subcostal (A) and left parasternal (B) views, with a large ventricular septal defect and an overriding aorta (Ao) LV, Left ventricle; RV, right ventricle Computed Tomography Angiography and Magnetic Resonance Imaging Although cardiac catheterization with direct angiography is the gold standard, it has been our practice more recently to obtain a computed tomography angiogram to delineate the anatomy of the pulmonary arteries and MAPCAs in newborns (Fig 36.11) as well as the anatomy of the upper and lower airways Other groups have also reported that a high-quality computed tomography