Investigation of Tetralogy of Fallot in Neonates

Plain-language summary

Child health serves as the foundation for overall public health, with neonatal mortality recognized globally as a comprehensive indicator of national health standards and societal advancement. The Healthy Children Action Improvement Plan (2021-2025) sets a national target to reduce neonatal mortality in China to below 3.1‰. Congenital heart disease (CHD), the most prevalent congenital defect among neonates, constitutes a significant cause of disability and premature death in the Chinese population. Annually, approximately 70,000-80,000 neonates are born with CHD, among whom nearly 10,000 present with critical congenital heart disease (CCHD). Postnatal manifestations of CCHD often include cyanosis, hypoperfusion, and respiratory distress, with untreated cases resulting in approximately 50% mortality. CCHD is one of the leading causes of infant death. Tetralogy of Fallot (TOF), the most common form of CCHD, accounts for a substantial proportion of cyanotic congenital heart diseases. It is characterized by four anatomical abnormalities: ventricular septal defect, pulmonary stenosis, overriding aorta, and right ventricular hypertrophy. These structural defects disrupt intracardiac blood flow, reduce arterial oxygen saturation, and result in cyanosis and other related symptoms. Untreated TOF leads to significant health issues early in life, including growth retardation, recurrent hypoxic episodes, heart failure, and increased susceptibility to infections. Long-term survival is markedly reduced, with only a small proportion surviving into adulthood. Thus, surgical intervention is pivotal for improving outcomes in TOF(Tetralogy of Fallot) patients. Despite advances in medical technology yielding satisfactory early outcomes, long-term prognosis following TOF correction remains a challenge. Historically, surgical strategies emphasized complete relief of right ventricular outflow tract obstruction, often at the expense of pulmonary valve function. Recent studies, however, highlight the critical role of preserving pulmonary valve function in improving long-term outcomes, as pulmonary valve dysfunction is a leading cause of late right ventricular failure and reintervention. Additionally, surgical approaches, whether via atrial or ventricular access, have inherent advantages and limitations, but neither can fully eliminate the risk of postoperative arrhythmias associated with TOF's anatomical complexity and surgical impact. These issues underscore the necessity for further advancements in long-term management strategies. Surgical correction of TOF in a single-stage procedure has become standard practice, with the timing of surgery progressively shifting to earlier ages-from school age in the 1990s to the current standard of 3-6 months of age. This timing ensures sufficient weight and organ maturity to withstand the complexities of cardiac surgery. However, in clinical practice, significant challenges persist, including: (1) Deterioration during the waiting period, during which patients may experience recurrent hypoxic episodes, inadequate weight gain, and exacerbated pulmonary vascular underdevelopment, thereby complicating definitive surgery and increasing perioperative risk. (2) Developmental delays due to chronic hypoxemia and heart failure, potentially leading to neurological deficits and pulmonary hypertension, adversely affecting cognitive and motor development. Neonatal repair, performed within 28 days of life, may mitigate these challenges by restoring normal circulatory physiology at the earliest possible stage. International guidelines endorse neonatal TOF repair for capable centers, citing the potential for enhanced clinical benefits and superior prognoses. Clinical observations at our center indicate several advantages of neonatal TOF repair, including reduced intraoperative bleeding, cleaner surgical fields, and better pulmonary vascular development. These benefits may be attributed to the regenerative potential of neonatal myocardial cells and the absence of prolonged pathological circulatory states, which otherwise exacerbate anatomical abnormalities. Early intervention may reduce right ventricular fibrosis and pulmonary vascular pathology, thereby improving long-term outcomes. With advancements in surgical techniques and perioperative care, neonatal TOF repair has become a routine practice at our center, with over 100 cases performed annually for two consecutive years. This success is supported by an integrated prenatal-to-postnatal care model, establishing a comprehensive treatment framework. Given this context, the investigators propose a multicenter, randomized controlled trial (RCT) to compare the safety and efficacy of neonatal and infant TOF repair. This study aims to provide high-quality evidence for clinical practice, determine optimal surgical timing, and enhance overall survival rates and quality of life for TOF patients.

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