Prevalence of Structural Heart Diseases Detected by Handheld Echocardiographic Device in School-Age Children in Iran: The SHED LIGHT Study

Background: Structural heart disease (SHD) has great impacts on healthcare systems, creating further public health concerns. Proper data are scant regarding the magnitude of the affected population by SHD. Objectives: This study aimed to determine the prevalence of SHD among children and adolescents in an Iranian population. Methods: In this population-based study, a multistage cluster-random sampling was used to choose schools from the Tehran urban area. All students were examined using a handheld Vscan device by echocardiographer, and the results were concurrently supervised and interpreted by cardiologists. All the major findings were reevaluated in hospital clinics. Results: Of 15,130 students (6–18 years, 52.2% boys) who were examined, the prevalence of individuals with congenital heart disease (CHD) and cardiomyopathy was 152 (10.046 per 1,000 persons) and 9 (0.595 per 1,000 persons), respectively. The prevalence of definite and borderline rheumatic heart disease (RHD) was 30 (2 per 1,000 persons) and 113 (7.5 per 1,000 persons), correspondingly. Non-rheumatic valvular heart disease (VHD) was also detected in 465 (30.7 per 1,000 persons) students. Of all the pathologies, only 39 (25.6%) cases with CHD and 1 (0.007%) cases with RHD had already been diagnosed. Parental consanguinity was the strongest predictor of CHD and SHD (odds ratio [OR]: 1.907, 95% CI, 1.358 to 2.680; P < 0.001 and OR, 1.855, 95% CI, 1.334 to 2.579; P < 0.001, respectively). The female sex (OR, 1.262, 95% CI, 1.013 to 1.573; P = 0.038) and fathers’ low literacy (OR, 1.872, 95% CI, 1.068 to 3.281; P = 0.029) were the strongest predictors of non-rheumatic VHD and RHD, correspondingly. Conclusions: The implementation of echocardiographic examinations for detecting SHD among young population is feasible which detected SHD prevalence in our population comparable to previous reports. Further studies are required to delineate its economic aspects for community-based screening.


Echocardiographic examinations
Echocardiographic examinations were performed using a pocket-sized ultrasound device (Vscan, GE Healthcare, Milwaukee, WI, USA). The Vscan echo machine weighs 391 g and is 13.5 × 7.4 × 2.8 cm in size. The device provides 2D grayscale and color Doppler images obtained with a 1.7-3.8 MHz phased-array transducer. It does not possess zoom, spectral Doppler, or the ability to perform velocity or time measurements.
The interpretation of valvular heart disease (VHD) was qualitatively performed. Valvular regurgitation was categorized into mild, moderate, or severe based on color-flow mapping. For the assessment of the severity of aortic insufficiency and pulmonary insufficiency, eyeball assessment of the regurgitant jet width was drawn upon. Accordingly, regurgitant jets of less than 20%, between 20% and 50%, and greater than 50% of the annulus diameter were considered mild, moderate, and severe regurgitation, respectively. Mitral regurgitation and tricuspid regurgitation were estimated based on the presence of central or lateral jets and by the eyeball assessment of the jet area to the left atrium and the right atrium, respectively. The grading of severity was similar to that in the aortic and tricuspid valves. The prolapse of the valves and valvular stenosis were interpreted as absent or present for being pathologic even for a mild lesion. Valvular leaflet motion, identified as normal or any restrictions or malcoaptation, was assessed by color turbulency. The identification of rheumatic heart disease (RHD) was based on the criteria of the World Heart Federation (WHF) [1]. However, since we used pocket-sized echocardiography with on-site interpretation, the simplified version was used for the detection of (ie, normal function vs mild, moderate, and severe dysfunction). The eyeball evaluation of the left ventricular ejection fraction was classified into 4 groups of greater than 55%, between 55% and 45%, between 45% and 35%, and less than 35% as normal, mild, moderate, and severe dysfunction, respectively. The heart chambers were evaluated qualitatively as normal, dilated, or hypoplastic/small. Large vessel abnormalities were also qualitatively reported as normal, dilated, or stenotic based on 2D images and color study. Any other congenital heart disease (CHD) or anatomic variations were reported when detected.

Electrocardiographic examinations
The electrocardiogram (ECG) was recorded by 4 technicians with more than 5 years of experience. The technicians work in a tertiary hospital and take at least 50 ECGs per working day. At the time of the examination, all ECGs were checked by cardiologists. In the event significant noises rendered an ECG uninterpretable, another ECG was recorded. The interpretation of traces was performed according to current international standards by a pediatric cardiologist with a fellowship in electrophysiology [3][4][5][6][7].
Supplementary table S1-Diagnostic criteria for screening of RHD using Vscan and standard transthoracic echocardiography

Screening criteria for Vscan
Pathologic MV regurgitation MV regurgitation jet >2 cm presents in any views which was estimated based on the scale at the border of sector and/or the eyeball assessment of jet area to the left atrium area >20% Both conditions in the absence of concomitant prolapse and congenital anomalies Pathologic AV regurgitation AV regurgitation presents in any views without prolapse and congenital anomalies Screening criteria for standard transthoracic echocardiography using WHF Pathologic MV regurgitation All of: 1) Regurgitation jet seen in 2 views; 2) with at least one view >2 cm; 3) with high velocity (>3 m/s); and 4) pan systolic jet in at least one envelope Pathologic AV regurgitation All of: 1) Regurgitation jet seen in 2 views; 2) with at least one view >1 cm;     Supplementary Fig S1. The areas of study located in the Tehran urban territory Supplementary Fig. S2 Age distribution of the studied population