|Year : 2015 | Volume
| Issue : 1 | Page : 23-26
Electrocardiographic characteristics of children with obstructive sleep apnea in a tertiary health center in Kano
Aliyu Ibrahim1, Abdulazeez Ahmed2
1 Department of Paediatrics, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
2 Department of Ear, Nose, Throat, Aminu Kano Teaching Hospital, Bayero University, Kano, Nigeria
|Date of Web Publication||5-Jan-2015|
Department of Paediatrics, Aminu Kano Teaching Hospital, Bayero University, Kano
Source of Support: None, Conflict of Interest: None
Background: Obstructive sleep apnea in children may be associated with cardiovascular complications and these may be identifiable on the electrocardiogram. Some of those changes seen in adults include ventricular hypertrophy and arrhythmias; however the exact prevalence of these in children is not known. Therefore, this study seeks to characterize the electrocardiographic features in children with obstructive sleep apnea.
Materials and Methods: This study reviewed 43 electrocardiograms (ECGs) of children clinically diagnosed with obstructive sleep apnea (OSAS) aged 4-14 years; their ECG parameters were compared with 43 apparently healthy controls matched for age and sex.
Results: There were 21 males and 22 females with male to female ratio of 1:1. The PR interval and QRS duration were higher in the obstructive sleep apnea group in the 4-9-year age group except for the QRS and P-wave axes. While in the 10-14-year-old age group lower values in the QRS axis, PR interval, QRS duration, and T-wave axis were recorded in those with obstructive sleep apnea; however, these were not statistically significant. The mean R- and S-waves amplitude in V 4 R, V 2 , V 5 and V 6 though higher in the obstructive sleep apnea group, but were not statistically significant. Premature ventricular complex was identified in only one of the subjects, phasic sinus arrhythmia in three of the subjects, and two ECGs had premature junctional complexes. T-wave inversion involving precordial leads V 4 R to V 3 was most predominant in all the age groups
Conclusion: The ECG characteristics of children with OSAS in this study were comparable to previous report in children and the prevalence of arrhythmia was also low.
Keywords: Arrhythmias, electrocardiogram, Nigerian children, obstructive sleep apnea
|How to cite this article:|
Ibrahim A, Ahmed A. Electrocardiographic characteristics of children with obstructive sleep apnea in a tertiary health center in Kano. Nig J Cardiol 2015;12:23-6
|How to cite this URL:|
Ibrahim A, Ahmed A. Electrocardiographic characteristics of children with obstructive sleep apnea in a tertiary health center in Kano. Nig J Cardiol [serial online] 2015 [cited 2021 Dec 4];12:23-6. Available from: https://www.nigjcardiol.org/text.asp?2015/12/1/23/148482
| Introduction|| |
Children are prone to upper respiratory tract infection (URI) - especially tonsillar, pharyngeal infections - and may have up to 6-8 episodes in a year. ,,,
Obstructive complication following URI may set in especially in those with concomitant craniofacial defects resulting in narrowing of the upper airway. These problems are most manifested during sleep resulting in sleep-disordered breathing such as snoring and obstructive sleep apnea  (OSAS); these at times, requiring tonsillectomy and adeno-tonsillectomy. ,
The gold standard for diagnosing OSAS is overnight polysomnography in a sleep laboratory which is scarce in most developing countries; therefore diagnosis in such settings is mostly clinical.
Airway obstruction may occasionally result in severe hypoxemia leading to cardiovascular complications such as arrhythmias, systemic and pulmonary hypertension, and right ventricular hypertrophy , and these changes may manifest on the electrocardiogram (ECG). This communication therefore seeks to review the ECG of children who had tonsillectomy/adeno-tonsillectomy due to OSAS over a two-year period between January 2009 and December 2010 to determine their characteristics and presence of arrhythmias.
| Materials and methods|| |
In a retrospective descriptive study, the ECGs of children aged 4-14 years prepared for tonsillectomy and adeno-tonsillectomy for OSAS at our center between January 2009 and December 2010 were reviewed. 
Information extracted from the case notes included: Age, gender, and ECG characteristics. Owing to the absence of generally accepted ECG reference standards among Nigerian children, their ECG characteristics were matched with those of apparently healthy children of the same age and gender seen in the Pediatrics Outpatient Department during well 'child follow-up visitation' over 6-week period between May and June 2014. The subjects were classified into two age groups: 4-9 years and 10-14 years.
Ethical approval was obtained from the Ethics Committee of Aminu Kano Teaching Hospital, Kano; while informed written consent was obtained from caregivers/parents of subjects in the control group. Patients with other co-morbidities such as congenital heart disease, sickle cell anemia, and with incomplete case records were excluded. For the control group, those who declined consent were excluded. ECG characteristics of 43 out of 67 children who had adeno-tonsillectomy were used in this study (24 of the ECGs were excluded because the subjects had other co-morbidities such as sickle cell anemia, congenital, and acquired heart diseases).
The ECG machine used for this study was a portable heated stylus direct writing AT-2 Swiss made electrocardiograph (Schiller AG cardiovit CH6341) with a frequency of 150 Hz and sampling frequency of 1000 Hz, with speeds of 25 mm/sec and 50 mm/sec, and three levels of sensitivity at 5, 10, and 20 mm/mV. Unipolar, bipolar limb leads, and chest leads with European color coding system were used. The 6-second method was used for heart rate calculation, the hex-axial method was used for the axes calculation and the clearest leads were used for interpretation. All measurements and interpretations were done manually by the authors with the aid of caliper and magnifying glass.
| Data analysis|| |
Statistical Package for Social Sciences (SPSS for Windows, version 19) software was used to analyze this data. Summary statistics such as frequency, mean, and standard deviation were employed while mean values were compared using student's t-test with a P-value less than 0.05 set as statistically significant.
| Results|| |
Forty-three (64.1%) ECGs were analyzed among 67 patients who had adenoidectomy/tonsillectomy for OSAS. Of the 43 subjects, there were 22 females and 21 males with female to male ratio of 1:1 among the ECG reviewed and their ages ranged between 4 and 14 years. Similarly 43 ECGs were done among healthy controls with 22 females and 21 males and female:male ratio of 1:1; their ages ranged between 4 and 14 years. [Table 1] shows that the differences of the mean ages of both study groups were not statistically significant for both the age groups (t = 0.285, P = 0.78 for the 4-9 years age group; t = 0.813, P = 0.42 for the 10-14 years age group).
Most of the ECG variables were higher in those with OSAS especially in the 4-9-year-old group except for the QRS and P-wave axes. While in the 10-14-year-old age group lower values in the QRS axis, PR interval, QRS duration, and T-wave axis were recorded in those with obstructive apnea; however, these differences were not statistically significant (P = 0.53, P = 0.81, P = 0.25, and P = 0.40, respectively) [Table 2] .
The mean R/S ratio on the right precordial lead V 4 R was less than 1 in all the study groups, while the mean R amplitude in V 4 R, V 2 , V 5 and V 6 though higher in the OSAS group, these differences were not statistically significant. Similarly the mean S-waves amplitude in V 4 R, V 2 , V 5 , and V 6 were higher in the OSAS group but these were not statistically significant [Table 3] and [Table 4].
Premature ventricular complex was identified in only one of the subjects, phasic sinus arrhythmia in three of the subjects, and two ECGs had premature junctional complexes.
T-wave inversion involving precordial leads V 4 R to V 3 was most predominate in all the age groups [Table 5] and [Figure 1].
|Figure 1: T-wave inversion with prominent R-wave in the right precordial leads|
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|Table 5: Percentage distribution of T-wave inversion on the precordial leads|
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| Discussion|| |
The exact prevalence of OSAS is not known worldwide. However, some reports have quoted 1-4%;  this difficulty has been attributed to variations in the modality of diagnosing OSAS especially in different settings where the gold standard for ascertaining diagnosis is lacking. Diagnosis based purely on history, clinically examination, audiotaping, and videotaping has appreciable sensitivity and specificity; and has been found to be of immense importance in resource limited settings. 
Recurrent hypoxia or long-standing hypoxia from chronic upper airway obstruction may be associated with cardiovascular complications. Both ventricles of the heart may be affected resulting to ventricular hypertrophy, cor pulmonale, and in severe cases in heart failure.  These changes may manifest on the ECG; the mean ECG values for most of the variables such as the R-waves, S-waves though higher in those with OSAS when compared with the control subjects; but were not statistically significant.
The exact mechanism of arrhythmias in OSAS is not completely understood, some attribute it to the influence of hypoxia; continued inspiratory effort through a closed upper airway resulting in arousal and termination of sleep. These result in release of hormonal, neuro-endocrines secretions such as leptin, growth hormone, catecholamine resulting in increased risk of arrhythmia and these coupled with autonomic dysregulation. Which has negative impact on the heart and hemodynamic state predisposes to arrhythmia formation.  It occurs mostly during episodes of sleep, therefore they may not manifest during the wakeful state.
Cardiac arrhythmias have been reported in about 30%-50% of adult patients with OSAS and it occurs mostly during episodes of apnea.  Associated structural heart diseases further worsen the risk of arrhythmias.  Arrhythmias such as brady-arrhythmia, tachyarrhythmia, and atrial fibrillation , have been reported in OSAS, though the exact prevalence in children is unknown; , however, this study recorded only a case of premature ventricular complex, two of premature junctional complexes and three cases of phasic sinus arrhythmia-which is considered a normal variant. Furthermore increased heart rate was observed in the OSAS group and statistical significance was recorded in the 10-14-year age group; these findings were similar to those of Khositseth et al. 
There was a significant difference in PR interval in the 4-9 years group with the OSAS group having longer PR interval. Therefore, there may be tendency toward heart block in children in the affected age group with OSAS. Presence of T-wave inversion was also documented in this report; however, the pattern was not different from previous reports among apparently healthy Nigerians. ,,
| Conclusion|| |
The ECG characteristics of children with OSAS in this study were comparable to previous report in children and the prevalence of arrhythmia was also low.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]