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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 16  |  Issue : 1  |  Page : 49-53

Normogram of right ventricular echocardiographic dimensions 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 Submission10-Jun-2019
Date of Acceptance12-Jun-2019
Date of Web Publication22-Oct-2019

Correspondence Address:
Dr. 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_11_19

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  Abstract 


Introduction: The study of the right ventricle is a relatively young field, particularly in the newborn. This study assessed the right ventricular echocardiographic dimensions in a cohort of normal term neonates in Ibadan.
Materials and Methods: This was a longitudinal cohort study involving 120 term neonates with normal maternal cardio topographic (CTG) parameters, physical findings, and oxygen saturation. The right ventricular dimensions were measured at birth and then weekly till age 28 days. The measurements obtained in millimeters were as follows: the main pulmonary artery, right ventricular anterior wall thickness, right ventricular diameter in diastole, interventricular septum thickness in diastole, and interventricular septal thickness in systole. Echocardiographic assessment was done with the Sonosite Titan mobile ultrasound machine with 5.0MHz transducer; measurements were made according to the American Society of Echocardiography recommendations.
Results: A total of 120 normal term newborns were studied, of which 60 males and 60 females. The mean weight varied from 3.16 to 4.02 kg, the length varied from 48.25 to 54.38 cm, whereas the body surface area varied from 0.036/m2 to 0.037/m2. The mean values and their respective standard deviations relative to the echocardiographic measurements are presented and right ventricular normograms derived from echo parameters and weight using 95% confidence interval.
Conclusions: This study has focused on right ventricular echocardiographic dimensions in normal newborn using a longitudinal cohort of newborn evaluated using CTG and pulse oximetry monitoring, thus demonstrating true normal zero probability of recruiting asphyxiated babies. The parameters thus can be used for evaluating Nigerian newborns pending the availability of results from larger multicenter studies.

Keywords: Echocardiography, neonates, normogram, right ventricle


How to cite this article:
Ashubu O, Ayede AI, Adebayo B, Omokhodion SI. Normogram of right ventricular echocardiographic dimensions in a cohort of normal term neonates in Ibadan. Nig J Cardiol 2019;16:49-53

How to cite this URL:
Ashubu O, Ayede AI, Adebayo B, Omokhodion SI. Normogram of right ventricular echocardiographic dimensions in a cohort of normal term neonates in Ibadan. Nig J Cardiol [serial online] 2019 [cited 2019 Dec 10];16:49-53. Available from: http://www.nigjcardiol.org/text.asp?2019/16/1/49/269645




  Introduction Top


The right ventricle (RV) in the newborn has been described over time as a complex entity to evaluate due to its complex structure; making the quantitative assessment of RV size and function being described as often difficult.[1] The RV not only serves as a conduit but it also has an essential contribution to normal cardiac pump function. In the past, the importance of RV function has been underestimated; however, there has been a change in thought concerning this in recent times. There is a paucity of echocardiographic data describing RV dimensions. The study of the RV is a relatively young field.[2] This study assessed the right ventricular echocardiographic dimensions in a cohort of normal term neonates in Ibadan.


  Materials and Methods Top


Study design

The study was a longitudinal cohort type involving 120 normal term neonates identified at birth and followed up for a total of 2 months.

Study site

The study was conducted in the University College Hospital (UCH), Ibadan and Adeoyo Maternity Teaching Hospital, Ibadan. These are the two biggest referral hospitals serving Ibadan, neighboring communities and states. The babies were recruited between March and December 2015.

Ethical approval

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

Recruitment of the study participants

Case record notes of women presenting in labor at term in the two hospitals were evaluated for eligibility. They were eligible for monitoring only if they did not have medical conditions that could predispose their babies to asphyxia. Eligible women were then monitored during the second stage of labor using cardio topographic (CTG) 7 fetal/maternal monitor. Newborns that were delivered by normal vaginal delivery were further assessed by carrying out the appearance, pulse, Grimace, Activity, and Respiration (APGAR) scoring, clinical examination, and pulse oximetry. Only newborns fulfilling the following inclusion and exclusion criteria were recruited.

Inclusion criteria

The inclusion criteria were as follows:

  1. Gestational age between 37 and 42 weeks
  2. Fetal heart rate of 110–160 beats/min
  3. Fetal heart variability of between 5 and 25 beats/min
  4. APGAR score of 7–10 at 1 and 5 min
  5. Birth weight of 2.50–4.00 kg
  6. Normal general and systemic physical examination
  7. SPO2 of 90%–100%
  8. Normal echocardiographic findings
  9. Parental/caregiver consent.


Exclusion criteria

The exclusion criteria were as follows:

  1. Absent deceleration and abnormal variability on CTG monitor
  2. Congenital birth defects on physical examination
  3. Pulmonary problems
  4. Cardiac lesions detected on echocardiogram
  5. Parental/caregiver refusal to give consent.


Recruitment continued consecutively until sample size of 120 was reached.

Estimation of sample size

The sample size was calculated using estimates of neonatal left ventricular end-systolic diameter (LVESD) from previous studies and assuming zα= standard normal deviate corresponding to a two-sided level of significance of 5% = 1.96 with level of precisionof 0.25 and standard deviation (SD) of LVESD of 1.25. This resulted in a sample size of 120. Each patient completing the study, however, would have been five times (day of birth, days 7, 14, 21, and 28) thus generating a total of 600 readings for each evaluated parameter in all the babies.

Echocardiographic assessment

Echocardiographic assessment was made with the Sonosite Titan mobile ultrasound machine with 5.0 MHz transducer; measurements were made according to the American Society of Echocardiography recommendations.[3] The imaging planes as identified by the transducer location were as follows: subxiphoid, apical, and right parasternal views for appropriate evaluation of cardiac anatomy.[4] The test was carried out when the newborns were asleep or if awake were calm. An initial echocardiogram was carried out to exclude congenital heart defects before the cardiac dimensions were measured. Pulse oximetry was also carried out using neonatal maximo pulse oximeter before each evaluation. The measurements obtained in millimeters were as follows: main pulmonary artery, right ventricular anterior wall thickness, right ventricular diameter in diastole, interventricular septum thickness in diastole, and interventricular septal thickness in systole. The mean and the SD of each echocardiographic dimension were calculated. The newborns were followed up every week till day 28 of life.

The pictorial locations for the right ventricular echo dimension measurements are shown in [Figure 1].
Figure 1: Illustration showing the sites where the measurements of the diastolic diameter of the right ventricle (ventricular diastolic diameter in the figure) and the left ventricle (VEd in the figure), left ventricle systolic diameter (VEs in the figure), diastolic thickness of interventricular septum (ESIV in the figure), and of the left ventricle posterior wall thickness (EPPVE in figure) were taken

Click here to view


Statistical analysis

The correlation between the echocardiographic measurements, weight, and age was carried out using Pearson's correlation coefficient. The study of the echocardiographic variables was complemented with the construction of a nomogram at the 5th and 95th centile using 95 confidence intervals.

All statistical analyses were performed considering a level of significance of 5% (P < 0.05).


  Results Top


One hundred and twenty normal term newborns were studied of which 60 males and 60 females. The mean weight varied from 3.16 to 4.02 kg, the length varied from 48.25 to 54.38 cm, whereas the body surface area (BSA) varied from 0.036/m2 to 0.037/m2. [Table 1] presents the mean values and their respective SDs relative to age, weight, length, BSA, whereas [Table 2] presents the mean values and their respective SDs relative to the echocardiographic measurements. [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6] represents the normograms derived from the echocardiographic measurements.
Table 1: Pearson's correlation coefficient (with associated 95% confidence limits) for linear relationships between the echocardiographic measurements, age, and weight

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Table 2: Means and standard deviations of echocardiographic measurements by age group

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Figure 2: Normogram of the mean right ventricular anterior wall diameter (mm) by the mean weight (kg)

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Figure 3: Normogram of the mean right ventricular end-diastolic diameter (mm) by the mean weight (kg)

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Figure 4: Normogram of the mean interventricular septum end-diastolic diameter (mm) by the mean body weight (kg)

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Figure 5: Normogram of the mean interventricular septum end-systolic diameter (mm) by the mean body weight (kg)

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Figure 6: Normogram of the mean pulmonary artery diameter (mm) by the mean body weight (kg)

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  Discussion Top


RV physiology was identified as a priority in cardiovascular research in 2006 by the National Heart, Lung, and Blood Institute;[2] only a few studies then had addressed the prognostic importance of RV diastolic function. The difficulty in studying RV diastolic function was assumed to be the marked load dependence of RV filling indexes. RV function has been shown to be a major determinant of clinical outcome, and therefore, should be considered during clinical management and treatment.[1]

The right ventricular anterior wall end-diastolic thickness, interventricular septum end-diastolic thickness, and the interventricular septum end-systolic thickness were similar to that derived in previous studies.[5],[6],[7] Right ventricular end-diastolic diameter in this study was similar to that obtained by Güzeltaş and Eroǧlu[8] and Kampmann et al.[5] though the study groups were not exactly the same; it was smaller than that obtained by Hagan et al.[7] and Solinger et al.[6] This could be due to the fact that the former study like ours obtained the echocardiographic measurements according to the American Society of Echocardiography recommendations[3] while the latter two studies did not.

This study demonstrated a weak correlation between the body weight and the pulmonary artery, the right anterior wall thickness and the right ventricular dimension in diastole. Suleymanoglu, on the other hand, demonstrated a statistically significant positive relationship between body weight and height and right ventricular end-diastolic and end-systolic volumes.[9]

Kim et al.,[10] in Japan, demonstrated postnatal decreases in PA size as being negatively related to body weight. This study demonstrated a linear increase in the size of the pulmonary artery with a positive moderate correlation.

Studies done in the African population did not review the RV,[11] and hence, the findings in this study could not be compared with any in the study of African babies. Thus, the present study could add to the data bank of normograms for right ventricular dimensions in the newborn.


  Conclusions Top


This study has focused on right ventricular echocardiographic dimensions in normal newborn using a longitudinal cohort of newborn evaluated using CTG and pulse oximetry monitoring, thus demonstrating true normal zero probability of recruiting asphyxiated babies. The parameters thus can be used for evaluating Nigerian newborns pending the availability of results from larger multicenter studies.

Recommendations

Further studies, particularly larger multicenter studies across multiple different regions are needed with larger sample size to obtain more generalizable newborn nomograms.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Bleeker GB, Steendijk P, Holman ER, Yu CM, Breithardt OA, Kaandorp TA, et al. Assessing right ventricular function: The role of echocardiography and complementary technologies. Heart 2006;92 Suppl 1:i19-26.  Back to cited text no. 1
    
2.
Haddad F, Doyle R, Murphy DJ, Hunt SA. Right ventricular function in cardiovascular disease, part II: Pathophysiology, clinical importance, and management of right ventricular failure. Circulation 2008;117:1717-31.  Back to cited text no. 2
    
3.
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. 3
    
4.
Lai WW, Geva T, Shirali GS, Frommelt PC, Humes RA, Brook MM, et al. Guidelines and standards for performance of a pediatric echocardiogram: A report from the task force of the pediatric council of the American society of echocardiography. J Am Soc Echocardiogr 2006;19:1413-30.  Back to cited text no. 4
    
5.
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. 5
    
6.
Solinger R, Elbl F, Minhas K. Echocardiography in the normal neonate. Circulation 1973;47:108-18.  Back to cited text no. 6
    
7.
Hagan AD, Deely WJ, Sahn D, Friedman WF. Echocardiographic criteria for normal newborn infants. Circulation 1973;48:1221-6.  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.
Süleymanoǧlu S, Okutan V, Yozgat Y, Lenk MK. Determination of normal echocardiographic values for right ventricular volume in children with two-dimensional transthoracic echocardiography. Turk J Pediatr 2007;49:141-7.  Back to cited text no. 9
    
10.
Kim HS, Hong YM, Sohn S, Choi JY. Perinatal changes in size of the fetal great arteries. Korean Circ J 2009;39:414-7.  Back to cited text no. 10
    
11.
Oladokun R, Omokhodion S. Left ventricular dimensions and functional parameters in apparently normal Nigerian children. Cardiolo Trop 2002;28:65-71.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2]



 

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Introduction
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