THE ELECTROCARDIOGRAM IN APPARENTLY HEALTHY FULL TERM NIGERIAN NEONATES IN THE FIRST ONE WEEK OF LIFE PRESENTING AT THE JOS UNIVERSITY TEACHING HOSPITAL

Abstract

Background: The clinical use of electrocardiography is a continuously evolving field, with
proven benefit as a non invasive cardiovascular investigative tool.
Biologic variables such as age, sex, and race are known to affect the
electrocardiogram (ECG). Generally in the first two to three days of life, T waves in the right
praecordial leads (V1, V3R) of the ECG are normally upright and usually inverts in the
majority of infants during the first week of life. Also neonatal ECGs normally show right axis
deviations from birth with gradual progression to left axis deviation with age. Currently
ECG values for Caucasian children serve as reference values for interpreting the ECG of
African newborns and may not be appropriate as recent findings in African adult population
suggests the presence of variants which may not necessarily be pathological.
Objective: Due to the paucity of neonatal normative data, this study was embarked on
with the aim of determining the electrocardiographic pattern within the first week of life, of
apparently healthy full term neonates delivered at the Jos University Teaching Hospital.
Subjects and Methods: Standard 12 lead surface ECG were recorded from apparently
healthy newborns delivered at the Jos University Teaching Hospital in the first 24hours, at
24 to 48 hours, 48 to 72hours and at the 7th day of life. ECG variables calculated for each
subject included the cardiac rhythm, heart rate, mean frontal plane QRS axis, P wave and
T wave axes, PR and QTc intervals, R wave and S wave amplitudes.
Results: one hundred and thirty (130) apparently healthy neonates were recruited
(61females and 69 males). The calculated variables showed no significant gender
differences and were similar to published values for Caucasian neonates. The cardiac
rhythm was sinus, the mean heart rate was 134 ± 13 per minute in the first 24 hours of life
and 147 ± 7per minute by 7 days of age. The mean frontal plane QRS axis was 121 ±16
degree (range 70-170) and 104 ± 18 (64-170) degrees by the 7th day of life. The mean P
wave axis was 42 ± 12 degrees in the first 24hours of life and 46 ± 12 degrees at the 7th
day of life. The mean T wave axis was 35 ±19.6 degrees in the first 24 hours of life and 47
±10 degrees by 7days of life. The mean P wave duration was 0.05±0.01 second in the first
24 hours and at 24 to 48hours of life and dropped to 0.04±0.0 second by 48 to 72 hours
and on the 7th day of life. The mean PR interval was 0.10 ±0.02 second in the first 24 hours
of life and 0.10±0.01 seconds from the 2nd to the 7th days of life. The mean P- wave
amplitude increased from 1.3 ±0.4 mm in the first 24 hours of life to 1.6±0.6 mm by the 7th
day of life. The mean QTc interval was 0.39±0.03 in the first 24 hours of life, 0.40±0.02 at
ages 24 to 48 hours and 48 to 72 hours, and 0.39±0.02 by the 7th day of life.
Conclusion: The ECG variables in this study were generally found to be similar to
published Caucasian values, however the upper range QRS frontal plane axis tended to be
more leftward.

THE ELECTROCARDIOGRAM IN APPARENTLY HEALTHY FULL TERM NIGERIAN NEONATES IN THE FIRST ONE WEEK OF LIFE PRESENTING AT THE JOS UNIVERSITY TEACHING HOSPITAL