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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 16  |  Issue : 1  |  Page : 54-59

Left ventricular echocardiographic nomograms in a cohort of normal term neonates in Ibadan


Department of Paediatrics, College of Medicine, University College Hospital, University of Ibadan, Ibadan, Nigeria

Date of Submission11-Jun-2019
Date of Acceptance12-Jun-2019
Date of Web Publication22-Oct-2019

Correspondence Address:
Prof. Samuel I Omokhodion
Department of Paediatrics, College of Medicine, University College Hospital, University of Ibadan, Ibadan
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njc.njc_13_19

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  Abstract 


Background: Previous studies on neonatal cardiac dimensions in Africa were cross-sectional, evaluating mainly children with very few newborns. This study was carried out in a cohort of normal newborns with normal maternal cardiotocograms, systemic finding, and pulse oximetry at birth.
Materials and Methods: One-hundred and twenty term normal newborns were recruited from March 2015 to December 2015 from the Adeoyo Maternity Teaching Hospital and the University College Hospital, Ibadan, Oyo State, Southwest Nigeria. The mothers were monitored during labor using cardiotocography 7 fetal/maternal monitor to ensure that the baby suffered no perinatal stress. Pulse oximetry was also done at birth. Left ventricular dimension in diastole, left ventricular posterior wall thickness in diastole, left ventricular dimension in systole, and left ventricular posterior wall thickness in systole and aortic dimension were measured at birth and weekly till 28 days using M-mode according to American Society of Echocardiography.
Results: All mothers recruited had spontaneous vaginal delivery with normal cardiotocographic measurements. Appearance, pulse, grimace, activity, and respiration scores ranged between 7–8 at 1 min and 8–10 at 5 min. There were 60 (50%) males and 60 (50%) females. All of the left ventricular measurements showed a linear increase in their values with age. Nomograms have been plotted based on age using 95% confidence interval.
Conclusion: This study has shed some light on the possibility of deriving normal values of echocardiographic dimensions for this age group and derived nomogram. This has added to the already existing data on the nomograms of the newborn, especially in the Nigerian Newborn.

Keywords: Echocardiographic, left ventricular, nomograms, normal term neonates


How to cite this article:
Ayede AI, Ashubu O, Ogunkunle O, Omokhodion SI. Left ventricular echocardiographic nomograms in a cohort of normal term neonates in Ibadan. Nig J Cardiol 2019;16:54-9

How to cite this URL:
Ayede AI, Ashubu O, Ogunkunle O, Omokhodion SI. Left ventricular echocardiographic nomograms in a cohort of normal term neonates in Ibadan. Nig J Cardiol [serial online] 2019 [cited 2019 Nov 15];16:54-9. Available from: http://www.nigjcardiol.org/text.asp?2019/16/1/54/269646




  Introduction Top


An echocardiographic quantitative evaluation of the cardiac and vascular structures is often of critical importance for the diagnosis and management of congenital heart diseases.[1] There is a need to study a large proportion of healthy newborns so as to avoid bias in the clinical decision-making process. There is also a need for the development of graphs following the derivation of these parameters to allow measurements of a single patient to be compared to normal measurements of individuals with similar anthropometric parameters.[2] Echocardiography of normal neonates has shown a linear increase in aortic root diameter with increasing birth weight.[3] Quantitative evaluation of cardiac chamber dimensions in pediatric echocardiography is quite important, but nomograms for these structures are limited. Previous studies on neonatal cardiac dimensions in Africa were cross-sectional, evaluating mainly children with very few newborns, and the use of pulse oximetry as well as cardiotocographic evaluation during labor was not employed. This study was therefore carried out in a cohort of normal newborns defined as those with normal maternal cardiotocograms during latter phase of labor and normal pulse oximetry at birth.


  Materials and Methods Top


Study design

This was a longitudinal cohort study of 120 healthy newborns.

Study site

One-hundred and twenty term normal newborns were recruited from March 2015 to December 2015 from the Adeoyo Maternity Teaching Hospital and the University College Hospital, Ibadan, Oyo State, Southwest Nigeria. These are the two hospitals with the highest referrals in the state and which serve the entire Ibadan metropolis and environs.

Ethical approval

The ethical approval for the study was obtained from the University of Ibadan/University College Hospital Institutional Review Board (IRB) and the Ethical Review Committee of Oyo State Ministry of Health (AD13/479/530).

Study participants

Sixty male and 60 female neonates delivered through spontaneous vaginal delivery and who fulfilled eligibility criteria were recruited into the study. The mothers were monitored during labor using cardiotocography 7 fetal/maternal monitor to ensure that the baby suffered no perinatal stress. Baseline fetal heart rate of <110 bpm and >160 bpm with fetal heart rate variability of <5 bpm and >25 bpm with acceleration or deceleration of fetal heart rate was taken as abnormal findings, and such newborns were not recruited into the study. Other exclusion criteria were maternal/surgical conditions that can affect fetal perfusion, appearance, pulse, grimace, activity, and respiration (APGAR) score <7 at 1 min and 5 min, respectively, birth weight <2.5 kg and >4.0 kg and Spo2<90%.

Clinical evaluation

One hour after delivery, the newborns had a general physical examination including anthropometric measurements, pulse oximetry, blood pressure, and echocardiographic evaluation. Hereafter, they were evaluated weekly by assessing their anthropometric parameters, pulse oximetry, blood pressure, and echocardiographic values till 1 month of life. All anthropometric and echocardiographic measurements were done by full operational assessment (FOA). The weight and length were measured carried out with Seca® weighing scale and infantometer using standard operating procedures for weight and length measurement. The weighing scale was standardized at the beginning of the study with standard known weights and after every 20 babies till the end of the study. Ten percent of the echo parameters were randomly reevaluated by a senior pediatric cardiologist, and differences of >0.1 mm were rechecked. The ethical approvals for the study were obtained from the University of Ibadan/University College Hospital IRB code as well as Oyo State Ministry of Health ethics committee. A written informed consent was obtained from the parents/caregivers of all the newborns.

M-mode echocardiographic measurements were recorded in accordance with the American Society of Echocardiography recommendations.[4] The newborns were examined while lying supine without sedation using Sonosite Titan mobile echocardiographic machine. The echocardiographic dimensions were evaluated in relation to the body weight; the body surface area minimally changed in this age group. The following are the echocardiographic dimensions obtained in millimeters: left ventricular dimension in diastole, left ventricular posterior wall thickness in diastole, left ventricular dimension in systole, and left ventricular posterior wall thickness in systole and aortic dimension [Figure 1].
Figure 1: Echo image showing the measurements of the interventricular septum end-diastolic diameter, interventricular septum end-systolic diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left ventricular posterior wall end-diastolic thickness, and left ventricular posterior wall end-systolic thickness

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The percentages of left ventricular ejection fraction (EF) and shortening fraction were calculated manually using a standard formula.[5] Each measurement was repeated three times, and then, the mean of the measurements was taken. The newborns were reviewed weekly up to 1 month of life in the facilities or at home for babies that did not present for follow-up [Figure 2].
Figure 2: Picture of a newborn whose length is being taken with an infantometer

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Statistical analysis

Data analysis was performed using the Statistical Package for the Social Sciences program (version 21, Armonk, NY: IBM Corp). The mean and standard deviations (SDs) were obtained for the weight, height, and the occipitofrontal circumference. Further analysis was done using Pearson's correlation to measure the strength and direction of a linear relationship between the echocardiographic measurements and weight according to the day of life. P < 0.05 was taken as statistically significant. Nomograms were plotted using 95% confidence interval.


  Results Top


There were a total of 247 mothers evaluated, of which 17, 25, and 15 were excluded due to medical complications in pregnancy, lack of consent, and complications in labor, respectively. The lost to follow-up rate was approximately 30%. Recruitment and follow-up continued until the sample size of 120 was completed. Details are as shown in the consort diagram [Figure 3].
Figure 3: Consort diagram

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The baseline fetal heart rate was between 130/min and 155/min. All mothers recruited had spontaneous vaginal delivery. APGAR scores ranged between 7–8 at 1 min and 8–10 at 5 min. There were 60 (50%) males and 60 (50%) females.

Clinical examination findings of participants

The general examination findings of the participants were normal in all the newborns. [Table 1] shows the mean and SDs of the participants' weight, length, occipitofrontal circumference, and body surface area according to the day of life. The weight was noticed to have dropped on the first follow-up visit (7th day of life) but was regained by day 14. The body surface area did not change significantly in each newborn with increase in age during the study period.
Table 1: Mean and standard deviation of the weight, length, occipitofrontal circumference, and body surface area

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The lowest SpO2 recorded was 94%, while the highest SpO2 recorded was 99% within the 1st hour of life. Ten (8.3%) of the patients had cardiac murmurs, two (1.7%) of whom were detected to have coarctation of the aorta and a univentricular heart as revealed by echocardiography. These two newborns were excluded from the study and replaced. At the second follow-up visit, the other 8 newborns (6.7%) no longer had cardiac murmurs.

The left ventricular measurements are given as a mean and SD [Table 2] and [Table 3] while [Table 4] is for the correlation between the echocardioagraphic measurements, age and weigh. Normograms of echochadiographic measurements with weight (kg) are presented in [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10].
Table 2: Means and standard deviations of echocardiographic measurements by age group

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Table 3: The mean and standard deviation of the derived parameters of the left ventricular function by age group

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Table 4: Pearson's correlation coefficient (with associated 95% confidence limits) for linear relationships between the echocardiographic measurements, age and weight

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Figure 4: Nomogram of the mean left ventricular end-diastolic diameter (mm) by the mean body weight (kg)

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Figure 5: Nomogram of the mean left ventricular end-systolic diameter (mm) by the mean weight (kg)

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Figure 6: Nomogram of the mean left ventricular posterior wall end-diastolic thickness (mm) by the mean body weight (kg)

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Figure 7: Nomogram of the mean left ventricular posterior wall end-systolic thickness (mm) by the mean weight (kg)

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Figure 8: Nomogram of the mean aortic root dimension (mm) by the mean body weight (kg)

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Figure 9: Nomogram of the mean left ventricular ejection fraction (%) by the mean body weight (mm)

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Figure 10: Nomogram of the left ventricular fractional shortening (%) by the mean body weight (kg)

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  Discussion Top


This study showed a progressive increase in the values of the echocardiographic parameters measured with the age and weight of the newborns evaluated. Oladokun and Omokhodion[6] demonstrated increase in the echocardiographic parameters in the newborn period, although the number of newborns reviewed in this study was small.

The functional parameters, fractional shortening and EF, changed minimally with age in this study, as found in the study in Ibadan[6] and in developed countries.[7],[8],[9],[10],[11] This might suggest that despite a marked increase in the size of the left ventricle during normal growth and development, the percentage of blood ejected, the percentage shortening in the diameter, and the percentage wall thickness at each beat remain constant.[9]

Although the mean values of the normal data reported in this study are in agreement with some previously published data as earlier discussed, some differences were noted. The left ventricular end-diastolic diameter and left ventricular end-systolic diameter measurements were lower than previously conducted studies.[8],[12],[13],[14] These differences can be explained with the use of higher temporal and spatial resolutions for echocardiographic scanners, which yield a more exact measurement of cardiac structures; furthermore, echocardiographic measurements were recorded by several pediatric cardiologists in some of the studies.[12],[13],[14] In this study, the measurements were taken by a single individual.

This study correlated each ultrasound measurement with the weight of the newborn, and there were no significant correlations; this had been demonstrated by Hagan et al. in California.[14] Kim et al. in South Korea, however, demonstrated a positive correlation between the right and left heart dimensions and the body surface area; there was no relationship demonstrated between aortic dimension and increase in weight postnatally.[15] The newborns reviewed in this study were delivered through cesarean section and its influence cannot be excluded as a contributor to physiologic changes at birth. Despite Daubeney et al in Southampton also showed a high correlation between the body surface area and cardiac dimensions.[16] The similarities in the correlation between this study and that done by Hagan could be because both studies were solely conducted in the newborn, while the latter two studies had a small population of newborns. Nidorf et al.[17] while studying the aortic annulus, the left atrium, and the left ventricle demonstrated that the heart and great vessels grow in unison and at a predictable rate after birth. This increase was attributed to response to skeletal growth.

Previous studies have used weight and the body surface area to plot cardiac nomograms.[2],[8],[13]

In the newborn, the use of body surface area remains controversial; this is because an increase in body weight leads to a minimal increase in body surface area at this age.[8],[12],[13],[14],[18] Hence, the various cardiac dimensions have been plotted using weight in this study. The data obtained were plotted to represent the mean ± 2 SD reference range. This would help with appropriate interpretation of the derived values for proper assessment of the newborn heart dimensions.


  Conclusion Top


Nomograms based on large numbers of healthy newborns are limited, affecting the accuracy of the evaluation of the severity of a defect. This study has shed some light on the possibility of deriving normal values of echocardiographic dimensions for this age group and derived nomogram. This could add to the already existing data on the nomograms of the newborn, especially in the blacks.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Cantinotti M, Scalese M, Molinaro S, Murzi B, Passino C. Limitations of current echocardiographic nomograms for left ventricular, valvular, and arterial dimensions in children: A critical review. J Am Soc Echocardiogr 2012;25:142-52.  Back to cited text no. 1
    
2.
Epstein ML, Goldberg SJ, Allen HD, Konecke L, Wood J. Great vessel, cardiac chamber, and wall growth patterns in normal children. Circulation 1975;51:1124-9.  Back to cited text no. 2
    
3.
Walther FJ, Siassi B, King J, Wu PY. Normal values of aortic root measurements in neonates. Pediatric cardiology 1985;6:61-3.  Back to cited text no. 3
    
4.
Sahn D; The Committee on M-mode Standardization of the American Society of Echocardiography. Recommendations regarding quantitation in M-mode echocardiography: Results of a survey of echocardiographic measurements. Circulation 1978;58:1072-83.  Back to cited text no. 4
    
5.
Badano L, Fox K, Sicari R, Zamorano JL. The EAE textbook of echocardiography: Oxford, United Kingdom. Oxford University Press; 2011.  Back to cited text no. 5
    
6.
Oladokun R, Omokhodion S. Left ventricular dimensions and functional parameters in apparently normal Nigerian children. Cardiol Trop 2002;28:65-71.  Back to cited text no. 6
    
7.
Overbeek LI, Kapusta L, Peer PG, de Korte CL, Thijssen JM, Daniels O. New reference values for echocardiographic dimensions of healthy Dutch children. Eur J Echocardiogr 2006;7:113-21.  Back to cited text no. 7
    
8.
Güzeltaş A, Eroǧlu AG. Reference values for echocardiographic measurements of healthy newborns. Cardiol Young 2012;22:152-7.  Back to cited text no. 8
    
9.
Henry WL, Ware J, Gardin JM, Hepner SI, McKay J, Weiner M. Echocardiographic measurements in normal subjects. Growth-related changes that occur between infancy and early adulthood. Circulation 1978;57:278-85.  Back to cited text no. 9
    
10.
Agata Y, Hiraishi S, Oguchi K, Misawa H, Horiguchi Y, Fujino N, et al. Changes in left ventricular output from fetal to early neonatal life. J Pediatr 1991;119:441-5.  Back to cited text no. 10
    
11.
Gutgesell HP, Paquet M, Duff DF, McNamara DG. Evaluation of left ventricular size and function by echocardiography. Results in normal children. Circulation 1977;56:457-62.  Back to cited text no. 11
    
12.
Solinger R, Elbl F, Minhas K. Echocardiography in the normal neonate. Circulation 1973;47:108-18.  Back to cited text no. 12
    
13.
Kampmann C, Wiethoff CM, Wenzel A, Stolz G, Betancor M, Wippermann CF, et al. Normal values of M mode echocardiographic measurements of more than 2000 healthy infants and children in central Europe. Heart 2000;83:667-72.  Back to cited text no. 13
    
14.
Hagan AD, Deely WJ, Sahn D, Friedman WF. Echocardiographic criteria for normal newborn infants. Circulation 1973;48:1221-6.  Back to cited text no. 14
    
15.
Kim HS, Lee JY, Sul JH, Lee SK, Chin DS. Dimensions of cardiac chambers and great vessels by cross-sectional echocardiography in infants and children. Korean Circ J 1990;20:358-68.  Back to cited text no. 15
    
16.
Daubeney PE, Blackstone EH, Weintraub RG, Slavik Z, Scanlon J, Webber SA. Relationship of the dimension of cardiac structures to body size: An echocardiographic study in normal infants and children. Cardiol Young 1999;9:402-10.  Back to cited text no. 16
    
17.
Nidorf SM, Picard MH, Triulzi MO, Thomas JD, Newell J, King ME, et al. New perspectives in the assessment of cardiac chamber dimensions during development and adulthood. J Am Coll Cardiol 1992;19:983-8.  Back to cited text no. 17
    
18.
Lourenço A, Quelhas I, Varandas L, Machado I, Reis F, Sousa F, et al. Echocardiographic evaluation of the aortic and pulmonary valve areas in the newborn infant. Normal patterns. Port J Cardiol 1996;15:225-9, 182.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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