Key Laboratory of Birth Defects and Related Diseases of Women and Children of MOE, Department of Pediatrics, West China Second University Hospital, Sichuan University, Section Renmin S. Rd, 20 3Rd, Chengdu, 610041, Sichuan, China.
BMC Cardiovasc Disord. 2023 Mar 27;23(1):159. doi: 10.1186/s12872-023-03198-8.
Among all fetal heart block patients, > 50% cases are associated with maternal autoimmune diseases, and such patients should receive treatment. However, nearly half of fetal heart block cases involve a mother with negative results following autoimmune antibody screening. A few studies have reported long QT syndrome (LQTS) can also present as a severe fetal bradycardia, which does not respond to fetal treatment. Herein, we reported a rare case of an infant who presented with high-degree autoimmune-mediated fetal atrioventricular block (AVB) with LQTS induced by a novel KCNH2 variant. This case led us to review our prenatal therapeutic strategy.
A 1-year-old boy presented to our heart center having experienced syncope 5 times in the past year. He had previously presented with fetal bradycardia during the fetal stage from 27 + 3 gestational weeks. The fetal echocardiography demonstrated AVB (2:1 transmission). As the maternal autoimmune antibody results were positive, his mother had received dexamethasone treatment during pregnancy; subsequently, the fetal AVB had changed from 2:1 to 4:3 transmission with elevated ventricular beating rates. However, this patient was identified to have complete AVB after birth. The initial electrocardiogram and Holter measurements at hospital administration showed complete AVB, pleomorphic ventricular tachycardia, a prolonged QT interval (QT = 602 ms, corrected QT = 538 ms), and wide and deep inverted T-waves. Meanwhile, torsades de pointes could be observed in several transit ventricular tachycardias based on Holter monitoring review. Genetic testing revealed KCNH2 c.2483G > A variant-induced LQTS. An implantable cardioverter defibrillator device and permanent pacemaker were both considered as therapeutic alternations; his parents ultimately accepted the implantation of a permanent pacemaker.
For fetuses with autoimmune-mediated AVB, intrauterine treatment should still be pursued immediately. However, once the treatment outcomes are deemed unacceptable or unexpected, other genetic variant-related channelopathies should be highly suspected. If the fetus lacks a positive family history, fetal genetic testing should be recommended to improve the prognosis of such patients by introducing integrative therapeutic strategies between the prenatal and postnatal phases.
在所有胎儿心脏传导阻滞患者中，>50%的病例与母体自身免疫性疾病相关，此类患者应接受治疗。然而，几乎一半的胎儿心脏传导阻滞病例涉及自身免疫抗体筛查结果阴性的母亲。一些研究报告称，长 QT 综合征（LQTS）也可表现为严重胎儿心动过缓，且对胎儿治疗无反应。在此，我们报告了一例罕见病例，一名婴儿表现为高程度自身免疫介导的房室传导阻滞（AVB）伴由新型 KCNH2 变异引起的 LQTS。该病例促使我们回顾我们的产前治疗策略。
一名 1 岁男孩因过去一年发生 5 次晕厥而就诊于我们的心脏中心。他在胎儿期 27+3 孕周时曾出现胎儿心动过缓。胎儿超声心动图显示 AVB（2:1 传导）。由于母体自身抗体结果阳性，他的母亲在怀孕期间接受了地塞米松治疗；随后，胎儿 AVB 从 2:1 变为 4:3 传导，心室跳动率升高。然而，该患者出生后被诊断为完全性 AVB。入院时的初始心电图和动态心电图测量显示完全性 AVB、多形性室性心动过速、QT 间期延长（QT=602ms，校正 QT=538ms）、宽而深的倒置 T 波。同时，根据 Holter 监测回顾，观察到尖端扭转型室性心动过速中的扭转型室性心动过速。基因检测显示 KCNH2 c.2483G>A 变异引起的 LQTS。植入式心脏复律除颤器和永久性起搏器均被视为治疗选择；其父母最终接受了永久性起搏器的植入。
对于自身免疫性介导的 AVB 胎儿，仍应立即进行宫内治疗。然而，一旦治疗结果不理想或出乎意料，应高度怀疑其他与基因突变相关的通道病。如果胎儿缺乏阳性家族史，应建议进行胎儿基因检测，通过引入产前和产后阶段的综合治疗策略，改善此类患者的预后。
