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Ventricular septal defects (VSD) represent the most common congenital heart defect in newborns. We assessed the electrocardiographic characteristics of newborns with VSDs in a general population sample. The Copenhagen Baby Heart Study is a prospective population–based cohort study offering cardiac evaluation of newborns. Echocardiograms and electrocardiograms were obtained within 30 days after birth and systematically analysed. A VSD was identified in 530 newborns (mean age 11 ± 7 days, 42% boys). Newborns with VSDs had a more left-shifted QRS axis (116 ± 34 vs. 120 ± 3°, p = 0.02), and a higher S-wave amplitude in V1 (721 ± 584 vs. 636 ± 549 µV, p = 0.001) than controls. The largest differences were found in newborns with large or perimembraneous VSDs with a higher frequency of left axis deviation, higher S-wave amplitudes in V1, and higher R- and S-wave amplitudes in V6 compared with controls. R-waves in V1 and V6 were significantly associated to left ventricular mass, whereas S-waves in V1 and V6 were dependent on left ventricular end-diastolic diameter on echocardiography. Conclusion: Newborns with VSDs showed significant differences in QRS axis, and R- and S-wave precordial amplitudes compared to matched controls. Perimembranous and large VSDs had the greatest effect on the neonatal ECG. What is Known: • Ventricular septal defects in newborns are prevalent and may affect cardiac function and structure. What is New: • The Copenhagen Baby Heart Study is the largest study including a cohort of unselected newborns undergoing postnatal cardiac examination. • We found that newborns with VSD showed significant electrocardiographic differences depending on size and type of VSD compared with healthy newborns. [ABSTRACT FROM AUTHOR]

Background: The QRS axis represents the sum and orientation of the ventricular depolarization. Accurate interpretation of abnormalities in the QRS axis may facilitate early diagnosis of heart disease in newborns. We aimed at describing the evolution of the QRS axis during the first 4 weeks of life and provide reference values from healthy newborns. Methods: The Copenhagen Baby Heart Study is a prospective general population study that offered cardiac evaluation during the first month of life to all newborns delivered in the Copenhagen area. Results: Electrocardiograms from 12,317 newborns (52% boys; mean age 12 days) with normal echocardiograms were included. The median QRS axis was 119° at the ages 0–7 days and shifted leftward to 102° at the ages 22–28 days (p < 0.001). We found that girls had a significantly less pronounced right-shifted axis than boys (p < 0.001) and that increasing gestational age (GA) was associated with a more pronounced right-shifted axis (p < 0.05). Infant size did not affect the axis (p > 0.05). Only 0.5% had an axis within the interval 0 to −90° and 1.1% in the interval +240 to +30°. Conclusions: The QRS axis showed a gradual leftward-shift during the first 4 weeks of life and was affected by sex and GA but unaffected by infant size. Less than 1% of the newborns had a QRS axis between 0 and −90°. This study represents updated reference values, which may facilitate the clinical handling of newborns. [ABSTRACT FROM AUTHOR]

In pediatric echocardiography, reference intervals are required to distinguish normal variation from pathology. Left ventricular (LV) parameters are particularly important predictors of clinical outcome. However, data from healthy newborns are limited, and current reference intervals provide an inadequate approximation of normal reference ranges. Normative reference intervals and z -scores for 2-dimensional echocardiographic measurements of LV structure and function based on a large group of healthy newborns were developed. The study population included 13,454 healthy newborns from the Copenhagen Baby Heart Study who were born at term to healthy mothers, had an echocardiogram performed within 30 days of birth, and did not have congenital heart disease. To develop normative reference intervals, this study modeled 10 LV parameters as a function of body surface area through joint modeling of 4 statistical components. Infants in the study population (48.5% were female) had a median body surface area of 0.23 m2 (IQR: 0.22-0.25 m2) and median age of 12.0 days (IQR: 8.0-15.0 days) at examination. All normative reference intervals performed well in both sexes without stratification on infant sex. In contrast, creation of separate reference models for infants examined at <7 days of age and those examined at 7-30 days of age was necessary to optimize the performance of the reference intervals. This study provides normative reference intervals and z -scores for 10 clinical, widely used echocardiographic measures of LV structure and function based on a large cohort of newborns. These results provide highly needed reference material for clinical application by pediatric cardiologists. [Display omitted] [ABSTRACT FROM AUTHOR]