Supplementary Material for: Critical Coarctation of the Aorta in Selective Fetal Growth Restriction and the Role of Coronary Stent Implantation

<b><i>Introduction:</i></b> Monochorionic twins are at increased risk of congenital heart defects (CHDs). Up to 26% have a birth weight &lt;1,500 g, a CHD requiring neonatal surgery, therefore, poses particular challenges. <b><i>Objective:</i></b> The aim of the study was to describe pregnancy characteristics, perinatal management, and outcome of monochorionic twins diagnosed with critical coarctation of the aorta (CoA). <b><i>Methods:</i></b> We included monochorionic twins diagnosed with critical CoA (2010–2019) at 2 tertiary referral centers, and we systematically reviewed the literature regarding CoA in monochorionic twins. <b><i>Results:</i></b> Seven neonates were included. All were the smaller twin of pregnancies complicated by selective fetal growth restriction. The median gestational age at birth was 32 weeks (28–34). Birth weight of affected twins ranged as 670–1,800 g. One neonate underwent coarctectomy at the age of 1 month (2,330 g). Six underwent stent implantation, performed between day 8 and 40, followed by definitive coarctectomy between 4 and 9 months in 4. All 7 developed normally, except for 1 child with neurodevelopmental delay. Three co-twins had pulmonary stenosis, of whom 1 required balloon valvuloplasty. The literature review revealed 10 cases of CoA, all in the smaller twin. Six cases detected in the first weeks after birth were treated with prostaglandins alone, by repeated transcatheter angioplasty or by surgical repair, with good outcome in 2 out of 6. <b><i>Conclusions:</i></b> CoA specifically affects the smaller twin of growth discordant monochorionic twin pairs. Stent implantation is a feasible bridging therapy to surgery in these low birth weight neonates.

<b><i>引言：</i></b> 单绒毛膜双胎（monochorionic twins）发生先天性心脏缺陷（congenital heart defects, CHDs）的风险显著升高。其中高达26%的患儿出生体重低于1500g，而需接受新生儿外科手术干预的先天性心脏缺陷，更是面临特殊的临床挑战。
<b><i>研究目的：</i></b> 本研究旨在描述确诊为重症主动脉缩窄（critical coarctation of the aorta, CoA）的单绒毛膜双胎的妊娠特征、围产期管理方案及临床结局。
<b><i>研究方法：</i></b> 本研究纳入2010至2019年两家三级转诊中心确诊为重症主动脉缩窄的单绒毛膜双胎病例，并对单绒毛膜双胎合并主动脉缩窄的相关文献进行系统回顾。
<b><i>研究结果：</i></b> 共纳入7例新生儿，所有患儿均为合并选择性胎儿生长受限的妊娠中体积更小的双胎。新生儿出生时的中位胎龄为32周（范围28~34周），受累双胎的出生体重区间为670~1800g。1例新生儿于出生后1月龄（体重2330g）接受了主动脉缩窄矫治术。6例患儿接受了支架植入术，手术时机为出生后第8至40天，其中4例于术后4至9个月接受了确定性主动脉缩窄矫治术。7例患儿中仅1例存在神经发育迟缓，其余均发育正常。另有3例共存双胎合并肺动脉狭窄，其中1例需接受球囊瓣膜成形术。文献回顾共纳入10例主动脉缩窄病例，所有病例均发生于妊娠中的较小双胎。出生后最初几周确诊的6例患者分别仅接受前列腺素类药物治疗、反复经导管血管成形术或外科修复治疗，6例中仅2例预后良好。
<b><i>研究结论：</i></b> 重症主动脉缩窄特异性累及存在生长不一致的单绒毛膜双胎妊娠中的较小双胎。对于这类低出生体重新生儿，支架植入术是一种可行的外科过渡治疗方案。