Abstract：
We present a term newborn with atrial arrhythmia on the first day of life (DOL). An echocardiogram showed normal structure and normal function; laboratory testing showed normal electrolytes and thyroid function. After initiation of flecainide, the EKG on DOL 2 showed significant and increasing bradycardia with atrial arrhythmia and extremely prolonged QTc interval. Flecainide was stopped and esmolol started. After 6 h of treatment, atrial tachycardia was suppressed, and the rhythm converted to sinus. Genetic testing found variants of unknown significance in the ALPK3 gene and KCNQ1 gene, which has been associated with long QT syndrome (LQTs). LQTs in infants can present as bradycardia, 2:1 AV block, or torsades de pointes. Our review of the literature found only one other case report of atrial arrhythmia in a newborn with congenital LQTs. Diagnosis of LQTs via EKG alone is difficult in neonates since the ST segment and T wave on the first DOL are usually flattened, making correct measurement of the QTc interval difficult. β-blockers, the first line of treatment for LQTs, are known to shorten QTc intervals and prevent arrhythmia events. As in our patient, β-blockers may be helpful for atrial arrhythmia prevention in patients with adrenergically mediated atrial tachycardia. In conclusion, atrial arrhythmia with bradycardia can be a presentation of congenital LQTs and be difficult to recognize. For neonates with this presentation with no evidence of myocarditis, congenital heart disease, or significant respiratory illness, genetic congenital LQTs should be highly suspected, especially when associated with low resting heart rates.
摘要：
我们在生命的第一天（DOL）介绍了患有房性心律失常的足月新生儿。超声心动图显示结构正常，功能正常；实验室检查显示电解质和甲状腺功能正常。氟卡尼开始后,DOL2上的EKG显示明显且增加的心动过缓伴房性心律失常和QTc间期延长。停用氟卡尼，开始艾司洛尔。治疗6小时后，房性心动过速被抑制,心律转变为窦性心律.基因检测在ALPK3基因和KCNQ1基因中发现了未知意义的变异，与长QT综合征（LQT）相关。婴儿的LQT可表现为心动过缓，2:1房室传导阻滞,或尖端扭转。我们对文献的回顾发现，只有一例先天性LQT新生儿的房性心律失常。新生儿仅通过EKG诊断LQT是困难的，因为第一个DOL上的ST段和T波通常是扁平的，难以正确测量QTc间期。β-受体阻滞剂,LQT的一线治疗，已知可以缩短QTc间隔并预防心律失常事件。就像我们的病人一样，β受体阻滞剂可能有助于预防肾上腺介导的房性心动过速患者的房性心律失常。总之,房性心律失常伴心动过缓可能是先天性LQT的表现,且难以识别.对于没有心肌炎证据的新生儿，先天性心脏病,或严重的呼吸道疾病，应高度怀疑遗传性先天性LQT，尤其是当与低静息心率相关时。
