Electrocardiographic Evaluation of Normal Newborns in the First Week of Life – Observational Study

Abstract Background The neonatal period is marked by major changes in the cardiovascular system, especially in the first week of life. Unlike the adult population, studies on electrocardiogram (ECG) data in the neonatal period are scarce. This is the first study to describe electrocardiographic changes in a cohort of newborns with normal echocardiograms. Objectives To analyze the electrocardiographic patterns of a population of full-term NB, without any cardiac morphological or functional anomalies, and compare the results with the literature. Methods In this observational study, echocardiograms and ECG results from 94 newborns divided in three age groups (up to 24 hours, between 25 and 72 hours, and between 73 and 168 hours of life) were evaluated and compared with those reported by Davignon et al. A p-value <0.05 was considered statistically significant. Results There were significant differences in T-wave direction in leads V1 (p= 0.04), V2 (p= 0.02), V3 (p= 0.008) and V4 (p= 0.005) between the three age groups. There were differences between our findings and the current literature in most of the parameters. Conclusion Term newborns within 24 hours of life showed significantly more positive T waves than older ones. Many differences from the Davignon’s ECG parameters were found, particularly in the P, Q, R, S amplitudes, QRS duration, R/S and R+S. These findings indicate that more studies are needed for a definitive interpretation of the ECG in newborns.

研究背景：新生儿期以心血管系统的一系列重大生理变化为典型特征，尤其在出生后的第一周表现最为显著。与成人人群不同，针对新生儿期心电图（electrocardiogram, ECG）数据的相关研究较为匮乏。本研究为首项针对经超声心动图（echocardiogram）检查证实心脏结构与功能均正常的新生儿队列，系统描述其心电图变化特征的研究。

研究目的：分析无任何心脏形态或功能异常的足月新生儿（newborn, NB）群体的心电图模式，并将本研究结果与现有文献报道进行对比。

研究方法：本项观察性研究纳入94名新生儿，按出生后年龄分为三组：出生后24小时内、25~72小时、73~168小时，对其超声心动图及心电图结果进行评估，并将结果与Davignon等人的研究报道进行对比。本研究将p值<0.05作为判定统计学显著性的标准。

研究结果：三组新生儿在V1导联（p=0.04）、V2导联（p=0.02）、V3导联（p=0.008）及V4导联（p=0.005）的T波方向存在显著统计学差异。本研究的多数心电图参数结果与当前已有文献报道存在差异。

研究结论：出生后24小时内的足月新生儿，其T波阳性率显著高于出生时间更晚的新生儿。本研究发现与Davignon等人报道的心电图参数存在诸多差异，尤其体现在P波、Q波、R波、S波振幅，QRS时限，R/S比值及R+S振幅方面。上述结果表明，针对新生儿心电图的标准化解读尚需开展更多研究以达成确定性结论。