Study of congenital heart defects among neonates in Jos, Nigeria: prevalence and spectrum

Background: There are few reports of the prevalence of CHD in the neonatal period in sub-Saharan Africa. The only available study in Nigeria was carried out before the widespread availability of echocardiography in the country. We sought to determine the prevalence and spectrum of congenital heart defects (CHD) among neonates in Jos, Nigeria. Methods: This cross-sectional study enrolled neonates less than one week of age from the two largest hospitals and their immunisation centres. Relevant information was obtained and an echocardiogram was performed on each neonate. Results: There were 3 857 neonates recruited over a two-year period; male-to-female ratio was 1.1:1. A total of 111 babies had CHD, with a prevalence of 28.8 per 1 000. Sixty-four neonates had mild CHD, with a prevalence of 16.6 per 1 000, while moderate and severe CHD were found in 27 (7.0 per 1 000) and 20 (5.2 per 1 000), respectively. Conclusion: CHD is prevalent in Nigerian neonates and there is therefore a need for advocacy to improve access to its diagnosis at birth for appropriate management. The study was conducted in two tertiary heath institutions: the Jos University Teaching Hospital (JUTH) and the Plateau State Specialist Hospital (PSSH) in Jos, north-central Nigeria. They are the two largest hospitals in the city, which has a population of about 816 000 people.11 The two hospitals together handle an average of 30 to 40 deliveries weekly. Neonates are usually discharged 24 hours after uncomplicated vaginal delivery unless they are sick and admitted for in-patient care. Sick neonates born elsewhere may also be admitted for in-patient care in these hospitals, both of which have functional immunisation units that are equally accessible to neonates born elsewhere. The delivery, postnatal and immunisation units of the two hospitals served as recruitment points for the neonates in this study. This was a cross-sectional study to determine the prevalence and spectrum of CHD among neonates in the immediate postnatal period (first week of life) over a period of two years from February 2017 to January 2019. The study population included neonates delivered or attended to within the first week of life in JUTH and PSSH and their affiliated immunisation centres. All babies aged one week or younger, delivered or provided with treatment or immunisation services in JUTH and PSSH were eligible for the study as long as their mothers or caregivers provided written informed consent. A total-population approach to sampling was employed in this study where all babies who met the inclusion criteria in the two health institutions were recruited and sampled within the study period upon consent. The neonates were recruited on weekdays before their discharge from the hospital or before routine vaccinations at the immunisation centres. Approval for the study was obtained from the Institutional and Health Research Ethics Committee of JUTH, while permission was obtained from PSSH and the affiliated immunisation centre before the study commenced. Written informed consent was also obtained from each neonate’s mother or primary caregiver. Five residents in paediatrics at JUTH served as research assistants and were trained by the lead investigator for two days on the study protocol, administration of questionnaires, the required clinical examination, and documentation of findings, including echocardiogram findings. A semi-structured proforma developed specifically for this study was used to obtain clinical and demographic information about the neonates and their parents, from mothers/caregivers. Physical examination findings of the neonates were also documented in the proforma, which was pre-tested on 34 babies to identify and address ambiguities, determine ease of administration, appropriateness of the questions, and to estimate the average duration of data collection. Demographic and clinical information about every neonate was documented by the trained research assistants. Demographic data such as maternal parity, age and educational status of parents, the neonate’s gender, postnatal age, as well as gestational age at the time of delivery, were recorded. The neonates’ birth weights (taken immediately after birth) were obtained from their delivery records. Their crown-to-sole lengths and occipitofrontal circumferences (OFC) were measured in centimetres using an infantometer and non-stretchable tape, respectively, according to standard methods.12 Three measurements of each were taken and the average (to the nearest 0.1 cm) was determined and recorded. A transthoracic Doppler echocardiogram was performed by the lead researcher, who has been trained in and routinely performs paediatric echocardiography, on all the enrolled neonates using a Vivid e® portable echo machine (GE, China, May 2016). A diagnosis of CHD was made in any newborn with single or multiple structural heart defects. The diagnosis of the various types of CHD was made based on the ICD-10 diagnostic codes.13 The CHD were classified as cyanotic or acyanotic defects, based on the presence or absence of cyanosis, and also as mild, moderate or severe lesions.5,10-13 Mild lesions included small atrial septal defects (ASD) 3–5 mm in diameter, and small ventricular septal defects (VSD) < 3 mm in diameter. Other mild lesions included pulmonary stenosis (PS) with peak gradient < 30 mmHg, and bicuspid aortic valve without aortic stenosis or incompetence. Although patent ductus arteriosus (PDA) < 1.5 mm in diameter after the first week of life was also considered a mild lesion, since the study was carried out in the first week of life, PDA < 1.5 mm in diameter was not categorised as CHD in this study. (Small ASD was differentiated from a patent foramen ovale by the absence of a flap in the latter.13) Moderate lesions were: large ASD > 5 mm in diameter, moderate-sized PDA and VSD measuring 1.5–3 mm and 3–6 mm, respectively, complex forms of VSD associated with other CHD, non-critical coarctation of the aorta, moderate pulmonary stenosis with peak gradient of 30–60 mmHg, and mild-tomoderate aortic stenosis with ≤ 50 mmHg peak gradient. Severe lesions included all cyanotic CHD, as determined by the presence of central cyanosis, which was defined as oxygen saturation < 95% in the absence of other causes,14 and acyanotic CHD such as large VSD > 6 mm, large PDA > 3 mm, atrioventricular septal defects (AVSD), severe pulmonary stenosis with peak gradient > 60 mmHg, severe aortic stenosis > 50 mmHg peak gradient, and any critical CHD such as severe duct-dependent lesions requiring urgent surgical intervention for survival. These included hypoplastic left heart syndrome (HLHS), critical coarctation of the aorta (CoA), critical aortic stenosis, tricuspid atresia without shunt defects, total anomalous pulmonary venous connection (TAPVC) and severe tetralogy of Fallot (TOF).15 Septal defects were further classified based on the location of the defect in the septum: ostium primum, ostium secundum and sinus venosus defects for ASDs and peri-membranous, inlet, outlet and muscular defects for VSDs.16 Newborns found to have CHD were referred to the Paediatric Cardiology unit in JUTH for in-patient care or out-patient follow up, depending on the infant’s clinical condition. Pre-term neonates with PDA were managed according to the hospital’s protocol.