The spectrum of cardiac rate and rhythm in normal newborns

Abstract

The distribution and variation of cardiac rate and rhythm in normal neonates has previously received little attention. This has made clinical assessment of dysrhythmia in newborns difficult. We therefore performed continuous 24-hour electrocardiography in 29 normal newborn subjects (age range, 1 to 6 days; mean, 3.5 days). The ECG tapes were then analysed in detail to define the normal range of cardiac rate, conduction intervals, and rhythm during waking and sleeping periods. Maximum sinus rate (awake) ranged from 150 to 222 beats per minute (mean, 192 +/- 16 [SD]), and minimum rate (awake) from 78 to 140 beats per minute (mean, 107 +/- 15). During sleep, the maximum rate ranged from 125 to 210 (mean, 168 +/- 23) and the minimum from 72 to 120 beats per minute (mean, 92 +/- 11). The maximum variation in rate for any individual during the 24-hour period ranged from 73 to 134 beats per minute (mean, 100 +/- 17). Sinus rhythm predominated with mild irregularity occurring episodically in 24 and moderate irregularity in 4 infants. An isolated atrial premature beat was present in 2 subjects, and an atrioventricular (AV) junctional escape rhythm occurred in one other after a sinus pause of 840 msec. Ventricular premature beats or AV conduction abnormalities were not observed. The corrected QT interval (QTc) ranged from 0.298 to 0.514 sec (mean, 0.390 +/- 0.026). The maximum variation in QTc over 24 hours ranged from 0.052 to 0.160 sec (mean, 0.097 +/- 0.028). We conclude that cardiac rhythm and conduction appear more stable in normal newborns than in older normal subjects and that bradycardia, conduction defects, and ventricular ectopy of the type recently reported in young normal adults seem to be more uncommon in the neonatal period.

Study of Cardiac Rate and Rhythm Patterns in Ambulatory and Hospitalized Children

“…Those studies demonstrated that maximal, mean and minimal heart rates decrease with age whereas the incidence of first- and second-degree atrioventricular block, and that of supraventricular and uniform ventricular extrasystoles increase with age. Our findings in our ambulatory infants, children and adolescents are similar to those of previous studies [1,2,3,4,5,6,7,8]. These data, together with similar information in the literature, can be taken as a basis for the evaluation of pediatric ambulatory ECG.…”

“…Over the next decades, the usefulness of the technique for the diagnosis of disorders of rhythm and conduction was widely reported in adults and also in the pediatric population. Many studies [1,2,3,4,5,6,7,8] in healthy neonates, infants, children and adolescents reported frequent occurrences of short episodes of bradycardia, junctional escape beats or rhythms, first- and second-degree atrioventricular blocks, premature atrial beats and uniform ventricular premature contractions. Those studies demonstrated that maximal, mean and minimal heart rates decrease with age whereas the incidence of first- and second-degree atrioventricular block, and that of supraventricular and uniform ventricular extrasystoles increase with age.…”

“…The range of heart rate and the nature of heart rhythms have been documented in special populations of healthy neonates [1,2,3] and healthy ambulatory infants [3,4,5], children [3,4,5,6] and adolescents [3, 5, 7, 8]. …”

Clinical Utility of a Single 24-Hour Electrocardiogram in the Investigation of Patients with Suspected Cardiac Dysrhythm

“…This may, or may not, be true in individual cases. In particular, defined dysrhythm in the absence of symptoms should be viewed within the perspective of age-controlled normal rhythm spectra [1][2][3] and the presence or absence of underlying heart disease [4,12]. If, for example, abnormally frequent VEBs had been defined as >200/day for this study, which might be closer to the upper limit of normal for patients in the age range of the test sets, then the number of true negatives in each group would have risen, and, consequently, sen sitivity and overall clinical utility would fall.…”

Paroxysmal Vagal Overactivity, Apparent Life-Threatening Event and Sudden Infant Death

“…On the contrary, after the age of 8 months, the mean value of the spontaneous sinus pause recorded during Holter monitoring stays within 1,000 ms whereas the sinus pause induced during the OCR increases dramatically with age. According to our own findings established from a normal control population and infants referred for ALTE [36,37] and according to data in the literature on sinus rhythm [38][39][40][41][42], we have selected the following criteria in favor of VO: HR less than 80 bpm before age 1 month, HR less than 70 bpm before age 2 months, HR less than 60 bpm before age 1 year, or sinus pauses 11,000 ms, or ¢Fi 1 100, % RF 1 0.55 (i.e. an abrupt and brief deceleration of more than 100 bpm during a 10-second period).…”