10 Percutaneous Intervention in the Fetus, Including Postnatal Management
Future Directions
Annotated References
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Future Directions As candidate selection and technical modifications for the previously mentioned forms of fetal cardiac intervention continue to be refined, further fetal cardiac therapies are on the horizon Complete heart block is a particularly morbid diagnosis in the fetus, often leading to hydrops and demise,67 despite a variety of management practices.68,69 Efforts are underway to develop a minimally invasive, micropacemaker that may be implanted percutaneously in the fetus.70,71 Although studies remain in the preclinical phase, the development of miniaturized devices may lend itself to other fetal applications Beyond percutaneous fetal cardiac intervention, another emerging form of fetal therapy is maternal hyperoxygenation (see also Chapters 7 and 8) Maternal hyperoxygenation results in vasodilation of the fetal pulmonary vascular bed with increased pulmonary blood flow, particularly later in gestation Several groups have investigated the use of maternal hyperoxygenation to increase pulmonary venous return and therefore flow through the mitral valve, aortic valve, and aortic arch in fetuses with hypoplastic left heart structures.72–74 Although the early results are encouraging, this type of therapy might be applicable only in situations of reduced LV preload, such as premature restriction or closure of the foramen ovale or mildly hypoplastic left heart structures without discrete valvar stenosis or endocardial fibroelastosis Furthermore, the optimal dose and duration of maternal hyperoxygenation, as well as the potential side effects of chronic oxygen therapy to both the mother and the fetus, have yet to be defined As the field of fetal therapy evolves, innovative strategies are unfolding both within and beyond percutaneous intervention Hopefully, such strategies will pose less risk to both the fetus and the mother Multidisciplinary collaboration among pediatric cardiologists, pediatric cardiac surgeons, obstetricians/maternalfetal medicine specialists, anesthesiologists, and others will remain essential not only to provide the best care but also to maintain the safety and autonomy of the mother at the center of this new era of scientific discovery Annotated References Allan LD, Sharland G, Tynan MJ The natural history of the hypoplastic left heart syndrome Int J Cardiol 1989;25(3):341–343 One of the first natural history papers highlighting the evolution of severe fetal aortic stenosis in the fetus to hypoplastic left heart syndrome at the time of birth Emani SM, McElhinney DB, Tworetzky W, et al Staged left ventricular recruitment after singleventricle palliation in patients with borderline left heart hypoplasia J Am Coll Cardiol 2012;60(19):1966–1974 Description and analysis of surgical techniques for left ventricular rehabilitation Freud LR, McElhinney DB, Marshall AC, et al Fetal aortic valvuloplasty for evolving hypoplastic left heart syndrome: postnatal outcomes of the first 100 patients Circulation 2014;130(8):638–645 Report of the technical success and postnatal outcomes of the first 100 patients to undergo fetal aortic valvuloplasty by the Boston group Freud LR, Moon-Grady A, Escobar-Diaz MC, et al Low rate of prenatal diagnosis among neonates with critical aortic stenosis: insight into the natural history in utero Ultrasound Obstet Gynecol 2015;45(3):326–332 Natural history of late fetal aortic stenosis that responds to postnatal aortic valvuloplasty alone Friedman KG, Freud L, Escobar-Diaz M, et al Left ventricular remodeling and function in children with biventricular circulation after fetal aortic valvuloplasty Pediatr Cardiol 2015;36(7):1502–1509 Characterization of postnatal left ventricular remodeling among patients with a biventricular circulation after fetal aortic valvuloplasty Friedman KG, Sleeper LA, Freud LR, et al Improved technical success, postnatal outcomes and refined predictors of outcome for fetal aortic valvuloplasty Ultrasound Obstet Gynecol 2017 [Epub ahead of print] Most recently updated algorithm to identify optimal candidates for fetal aortic valvuloplasty Jantzen DW, Moon-Grady AJ, Morris SA, et al Hypoplastic left heart syndrome with intact or restrictive atrial septum: a report from the international fetal cardiac intervention registry Circulation 2017;136(14):1346–1349 Pooled results of outcomes of in utero atrial