Electrocardiographic characteristics of newborns with ventricular septal defects: a Copenhagen Baby Heart Study

Abstract

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.

Keywords: CBHS; Congenital heart defect; Copenhagen Baby Heart Study; Ventricular septal defect.

Fig. 1

A Maximum R-wave amplitude in lead V1, grouped by VSD size. B Maximal S-wave amplitude in lead V1, grouped by VSD size. C Maximal R-wave amplitude in V6 grouped by VSD size. D Maximal S-wave amplitude in V6 grouped by VSD size. Dots represent mean values, and bars represent ± 95% confidence intervals

Fig. 2

Linear regression of the QRS axis as a function of left ventricular mass (in grams), grouped by VSD type, and compared with controls. Perimembranous VSDs (red line) had significant influence on the effect of left ventricular mass on the QRS axis compared with controls (green line) and muscular VSDs (blue line; p = 0.0011)

Fig. 3

A R-wave amplitude in V1 as a function of left ventricular mass (LVM, in grams), grouped by VSD size. Though LVM was found to be significantly associated with R-wave amplitude in V1, when subgrouping by VSD size, no statistical significance for any VSD size was found. B R-wave amplitude in V6 as a function of left ventricular mass grouped by VSD size. When controlling for the effect of LVM, the V6 R-wave amplitude was influenced by the size of the VSD, and was significantly increased for large VSDs (p = 0.04). C S-wave amplitude in V1 as a function of left ventricular end-diastolic diameter (LVIDd), grouped by VSD size. When controlling for the effect of LVIDd, the V1 S-wave amplitude was influenced by the size of the VSD, and was significantly increased for small (p = 0.0056), moderate (p = 0.035), and large VSDs (p < 0.001) compared with controls. D S-wave amplitude in V6 as a function of LVIDd, grouped by VSD size. When controlling for the effect of LVIDd, the S-wave amplitude in V6 was influenced by the size of the VSD, and was significantly increased for large VSDs (p < 0.001) compared with controls. Shaded grey area represent 95% confidence interval