Supplementary Material for: Fetal-to-neonatal transition of an infant with Transposition of the Great Arteries and intact ventricular septum: a case report

Introduction: Transposition of the great arteries (TGA), especially with intact ventricular septum (TGA-IVS), presents unique challenges during fetal-to-neonatal transition, which can contribute to developing persistent pulmonary hypertension of the newborn (PPHN).
Case presentation: A male newborn with TGA-IVS, delivered via caesarean section, presented with hypoxemia and tachycardia immediately after birth (preductal SpO2: 50-60%, postductal SpO2: 70-75%). Echocardiography revealed a floppy interatrial septum and two interatrial connections with bidirectional shunting. Ductal flow showed systolic right-to-left shunting, suggesting high pulmonary vascular resistance.
Immediate post-birth management included non-invasive respiratory support with continuous positive airway pressure at 100% oxygen and administration of prostaglandin E2 to maintain ductal patency. Despite initial low oxygen saturation levels, escalation of intensive treatments was deferred based on continuous trend monitoring of vital signs and echocardiographic indicators. Oxygenation and circulation gradually improved within the first 2 hours after birth to normal values, obviating escalation of intensive interventions like intubation, nitric oxide and/or balloon atrial septostomy. Arterial switch operation at day 3 post-birth was successful.
Conclusion: This case highlights the possible contribution of fetal-to-neonatal transition in TGA-IVS to developing PPHN, which may subside after transition. Moreover, the potential for providing a gentle hemodynamic transition without invariably needing early invasive interventions after birth.

引言：大动脉转位（TGA），特别是伴完整室间隔（TGA-IVS）者，在胎儿至新生儿过渡期间面临独特的挑战，这可能导致新生儿持续性肺动脉高压（PPHN）的形成。
病例介绍：一名经剖腹产出生的TGA-IVS男性新生儿，出生后即刻出现低氧血症和心动过速（出生前导管前SpO2：50-60%，导管后SpO2：70-75%）。超声心动图显示可动性心房中隔及两个心房间交通，存在双向分流。导管血流显示收缩期右至左分流，提示肺血管阻力较高。
出生后即刻管理包括使用100%氧气的持续正压通气进行非侵入性呼吸支持，以及给予前列环素E2以维持导管通畅。尽管初始氧饱和度较低，但基于生命体征和超声心动图指标的持续趋势监测，推迟了强化治疗的升级。出生后前2小时内，氧合和循环逐渐恢复正常，避免了插管、一氧化氮和/或球囊房间隔造口等强化干预措施。出生后第3天进行的动脉切换手术成功。
结论：本案例突出了TGA-IVS在胎儿至新生儿过渡期间可能对PPHN形成的潜在贡献，这种状况可能在过渡后缓解。此外，提供了实现温和血流动力学过渡的可能性，无需在出生后不可避免地实施早期侵入性干预措施。