![]() ![]() As 70–80% of coronary flow occurs during diastole, coronary insufficiency due to this coronary steal may play an important role in the recognized incidence of mortality between the stage I and II operations. “Coronary steal” may result as diastolic retrograde flow occurs in both the coronary arteries and descending aorta. Due to the placement of the MBTS downstream of the neoaortic valve, there is continuous forward flow from the systemic to the pulmonary circulation in both systole and diastole following the Norwood procedure. In the classic Norwood procedure, a modified Blalock–Taussig shunt (MBTS) provides PBF from the innominate or subclavian artery to the pulmonary arteries via a polytetrafluoroethylene (PTFE) tube. While the first two requirements have remained largely unchanged, there are now two acceptable options for the source of the measured PBF. These requirements are, (1) unobstructed systemic outflow from the single right ventricle to a reconstructed aorta, (2) unobstructed pulmonary venous return into the right atrium and (3) controlled pulmonary blood flow (PBF). The requirements for the Norwood procedure have not changed from Dr. As this population grows, it becomes increasingly important to understand the longer-term outcomes of these Fontan patients, not only in terms of survival, but also burden of disease, neurodevelopmental outcomes, psychosocial development and quality of life. Regardless of the approach, traditional surgical staged palliation or the hybrid procedure, survivals have vastly improved, and large numbers of these patients are surviving not only through their Fontan in early childhood, but into adolescence and young adulthood. Proponents of this approach hope to not only improve short-term survival, but potentially longer-term outcomes, such as neurodevelopment, as well. The initial hybrid procedure is then followed by a “comprehensive” stage II, that combines components of both the Norwood and the traditional stage II, and later completion of the Fontan. In addition to modifications to the Norwood procedure, the “hybrid procedure,” a combined catheter-based and surgical approach, avoids the Norwood procedure in the newborn period entirely. The multi-institutional Single Ventricle Reconstruction trial randomized 555 patients to one or the other shunt, and these subjects continue to be followed closely as they now approach 10 years post-randomization. One significant change is a renewed interest in the right ventricle-to-pulmonary artery shunt as the source of pulmonary blood flow, rather than the modified Blalock-Taussig shunt for the Norwood. This traditional three-stage surgical palliation has seen several innovations in the past decade aimed at improving outcomes, particularly for the Norwood procedure. Yet, despite this fact, experienced centers now report hospital survivals in excess of 90% for the Norwood. While the stage II operation (hemi-Fontan or bidirectional Glenn) and stage III Fontan procedure have evolved into relatively low risk operations, the stage I Norwood procedure remains one of the highest risk and costliest common operations performed in congenital heart surgery. ![]() Universally fatal only four decades ago, the progress in the three-stage palliation of hypoplastic left heart syndrome and related single right ventricular lesions has drastically improved the outlook for these patients.
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