Racial variations in electrocardiograms and vectorcardiograms between black and white children and their genesis

Normal ECG standards and percentile charts for infants, children and adolescents

BACKGROUND

Normal ECG standards in newborns, infants, children and adolescents have been collected and published by many authors. Only those by Davignon et al., Rijinbeek et al. and our two studies covered all ages from birth to adolescence. The standards reflecting the growth and development of the heart in infants, children and adolescents remained to be studied and explored.

METHODS

We selected from our ECG database, after discussions and consultation, 15 key ECG parameters and analyzed for their age- and sex-specific mean, standard deviation and 2nd to 98th percentiles and their percentile charts were constructed.

RESULTS

The ranges and distributions of the normal ECG standards, means and 2nd to 98th percentiles of 15 key parameters were established.

CONCLUSION

A complete set of normal ECG standards of 15 key parameters from birth to adolescents is available for clinicians and researchers.

Reference values of electrographic and cardiac ultrasound parameters in Russian healthy children and adolescents

Between 2009 and 2013, a large cross-sectional study on the health consequences of the Chernobyl nuclear accident was performed in the contaminated and uncontaminated territories of the Bryansk Oblast (Russian Federation). The objective of this work was to confirm or refute a possible association between childhood cardiac arrhythmia and a chronic exposure to caesium-137. As part of this study, a large number of electrocardiographic and cardiac ultrasound parameters were collected from 18,152 children aged 2-18 years including 12,512 healthy ones not contaminated with caesium-137. It seemed therefore relevant for us to share in a second publication these medical data based on healthy and uncontaminated children with the scientific community because of the large quantities and the limited availability of such kind of data. In the present study, relating to electrocardiographic parameters, the measurements performed fully reflect the expected evolution of the paediatric electrocardiogram between 5 and 18 years of age. Thus, the median values were generally quite close to those available in the literature. In contrast, differences in the 2nd and 98th percentiles were notable and could be explained in particular by the type of equipment used, the number of subjects included in the study and racial disparities. As for echocardiographic parameters, the evolution of the measured values in age groups is consistent with what was expected considering factors such as growth. In comparison with other scientific studies that have investigated these echocardiographic parameters, some differences by age groups have been identified. The ethnic factor truly appears to be a relevant feature to consider. In view of the results, it appeared essential to the authors to approach the methodological conditions of the scientific studies already published on the topic to be truly comparable and thus to provide a reliable answer on a topic for which real expectations in terms of medical care are required.

Cardiac remodeling and hypertension in HIV uninfected infants exposed in utero to antiretroviral therapy

BACKGROUND

We aimed to assess the postnatal pattern of cardiovascular remodeling associated with intrauterine exposure to maternal HIV and antiretroviral treatment (ART).

METHODS

Prospective cohort including 34 HIV-exposed uninfected (HEU) infants and 53 non-HIV-exposed infants evaluated from fetal life up to 6 months postnatally. A cardiovascular evaluation was performed including echocardiography, blood pressure and carotid intima media thickness (cIMT) measurement.

RESULTS

ART regimens during pregnancy included two nucleoside reverse transcriptase inhibitors (Abacavir+Lamivudine (32.4%), Emtricitabine+Tenofovir (41.2%) and Zidovudine+Lamivudine (20.6%)). At 6 months of age, HIV-exposed uninfected infants showed thicker myocardial walls (septal wall thickness mean 5.02 mm (SD 0.85) vs 3.98 mm (0.86); p<0.001) and relative systolic dysfunction with decreased mitral ring displacement (8.57 mm (2.03) vs 10.34 mm (1.84); p=0.002) and decreased tricuspid S' (9.71 cm/s (1.94) vs 11.54 cm/s (2.07); p=0.003) together with relative diastolic dysfunction showed by prolonged left isovolumic relaxation time (58.57 ms (13.79) vs 47.94 (7.39); p<0.001). Vascular assessment showed significantly higher systolic and diastolic blood pressure (102 mmHg (16.1) vs 80 mmHg (13.9); p<0.001 and 64 mmHg (14.4) vs 55 mmHg (10.2); p=0.045 respectively), with 50% of HIV-exposed children meeting criteria for hypertension vs 3.77% of the non-HIV-exposed group (p<0.001) and thicker mean cIMT in the HIV-exposed group (0.62 µm (0.09) vs 0.51 µm (0.09); p=0.015).

CONCLUSIONS

Subclinical cardiac impairment together with higher blood pressure and thicker cIMT were observed in HIV-exposed infants at 6 months of age. Half of them presented hypertension. Our findings support a possible increased cardiovascular risk in HIV uninfected infants exposed in utero to ART.

Current diagnostic ECG criteria for left ventricular hypertrophy: is it time to change paradigm in the analysis of data?

BACKGROUND

Twelve-lead ECG represents the most common diagnostic tool in clinical cardiology and allows an immediate screening of left ventricular hypertrophy (LVH), but current criteria might have poor clinical usefulness in everyday clinical practice due to lack of sensitivity.

METHODS

The current study aims to review and compare the clinical performance of known ECG criteria of LVH in a real-life setting; 2134 patients had ECG and echocardiographic exams performed during the same hospitalization. All traces were retrospectively analysed, and the amplitudes of the waves were manually measured. Transthoracic echocardiography was considered as the gold standard to assess LVH.

RESULTS

LVH had a prevalence of 58%. Considering the diagnostic performance of ECG criteria for LVH, the Cornell voltage carried the best area under the receiver operating characteristic curve (0.678), while RaVF (R wave in aVF lead) had the poorer result (0.440). The R5/R6 criterion had the best sensitivity (60%), but with the worst specificity (37.4%). The 'Q or S aVR' had the best specificity (99.9%) but lacks sensitivity (0.80%). The Peguero Lo Presti criterion had a sensitivity of 42.3% and a specificity of 75.8%. The Cornell voltage and the Cornell product had similar area under the receiver operating characteristic curve values which were found to be significantly greater compared with other criteria.

CONCLUSION

Current ECG criteria of LVH have low sensitivity despite an acceptable specificity. Among these, Cornell voltage and Cornell product criteria were equally found to have a more accurate diagnostic performance compared with other criteria. To overcome the intrinsic limitations of the current ECG LVH criteria, a new paradigm in the analysis of electrocardiographic data might be necessary.

Electrocardiograms in Healthy North American Children in the Digital Age

BACKGROUND

Interpretation of pediatric ECGs is limited by lack of accurate sex- and race-specific normal reference values obtained with modern technology for all ages. We sought to obtain contemporary digital ECG measurements in healthy children from North America, to evaluate the effects of sex and race, and to compare our results to commonly used published datasets.

METHODS

Digital ECGs (12-lead) were retrospectively collected for children ≤18 years old with normal echocardiograms at 19 centers in the Pediatric Heart Network. Patients were classified into 36 groups: 6 age, 2 sex, and 3 race (white, black, and other/mixed) categories. Standard intervals and amplitudes were measured; mean±SD and 2nd/98th percentiles were determined by age group, sex, and race. For each parameter, multivariable analysis, stratified by age, was conducted using sex and race as predictors. Parameters were compared with 2 large pediatric ECG data sets.

RESULTS

Among ECGs from 2400 children, significant differences were found by sex and race categories. The corrected QT interval in lead II was greater for girls compared with boys for age groups ≥3 years (P≤0.03) and for whites compared with blacks for age groups ≥12 years (P<0.05). The R wave amplitude in V6 was greater for boys compared with girls for age groups ≥12 years (P<0.001), for blacks compared with white or other race categories for age groups ≥3 years (P≤0.006), and greater compared with a commonly used public data set for age groups ≥12 years (P<0.0001).

CONCLUSIONS

In this large, diverse cohort of healthy children, most ECG intervals and amplitudes varied by sex and race. These differences have important implications for interpreting pediatric ECGs in the modern era when used for diagnosis or screening, including thresholds for left ventricular hypertrophy.

Study on ECG in the Adolescent

Normal ECG values in newborns, infants, and children have been collected and published. ECG in the adolescent, however, remains, to be collected and studied. The present study was designed and carried out to establish the normal ECG standards in male and female adolescents. A total of 898 school children and adolescents screened and examined as healthy were divided by age and sex into 6-9, 9-13, and 13-18 years age-groups. A 12 lead conventional ECG was recorded in 10 mm/mV and 25 mm/s, utilizing an automated Fukuda Denshi FCP-4301, MS-DOS/IBM-AT ECG machine. Lead V3R was not taken. Analog-to-digital conversion was performed by Fukuda signal acquisition module at a sampling rate of 500 Hz. The data on 69 ECG parameters were analyzed for the mean, standard deviation, 2nd to 98th percentiles, 95% confidence intervals, and sex difference. Normal values on 69 ECG parameters, sex-specific heart rate, P-QRS-T interval, duration, axis, wave amplitude, and calculated R/S amplitude ratio and ventricular activation time by age-group and sex were established. Male and female difference was noted in 49 (71.0%) parameters, of which 3 (6.1%) began in 6-9 years age-group, 30 (61.2%) began in 9-13 years age-group, and 16 (32.7%) in 13-18 years age-group. No sex difference occurred in 20 (29.0%) parameters. Normal male and female ECG standards on 69 ECG parameters in the adolescent were established. ECG sex difference began to appear the earliest at ages 6-9 years, and it occurred mostly at ages 9-13 years and 13-18 years, reflecting the anatomical and physiological consequences of puberty.

Electrocardiographic findings in a middle-aged African population in the Seychelles islands

This study describes major electrocardiogram (ECG) measurements and diagnoses in a population of African individuals; most reference data have been collected in Caucasian populations and evidence exists for interethnic differences in ECG findings. This study was conducted in the Seychelles islands (Indian Ocean) and included 709 black individuals (343 men and 366 women) aged 25 to 64 years randomly selected from the general population. Resting ECG were recorded by using a validated ECG unit equipped with a measurement and interpretation software (Cardiovit AT-6, Schiller, Switzerland). The epidemiology of 14 basic ECG measurements, 6 composite criteria for left ventricular hypertrophy and 19 specific ECG diagnoses including abnormal rhythms, conduction abnormalities, repolarization abnormalities, and myocardial infarction were examined. Substantial gender and age differences were found for several ECG parameters. Moreover, tracings recorded in African individuals of the Seychelles differed from those collected similarly in Caucasian populations in many respects. For instance, heart rate was approximately 5 beats per minute lower in the African individuals than in selected Caucasian populations, prevalence of first degree atrio-ventricular block was especially high (4.8%), and the average Sokolow-Lyon voltage was markedly higher in African individuals of the Seychelles compared with black and white Americans. The integrated interpretation software detected "old myocardial infarction" in 3.8% of men and 0% of women and "old myocardial infarction possible" in 6.1% and 3%, respectively. Cardiac infarction injury scores are also provided. In conclusion, the study provides reference values for ECG findings in a specific population of people of African descent and stresses the need to systematically consider gender, age, and ethnicity when interpreting ECG tracings in individuals.

Echocardiographically determined left ventricular mass index in normal children, adolescents and young adults

Left ventricular hypertrophy is an important diagnostic and prognostic finding in children with cardiovascular disease, but there are currently no well established criteria for its determination by M-mode echocardiography. Three hundred thirty-four subjects, aged 6 to 23 years, who were free of cardiovascular disease were studied. Left ventricular mass was calculated using echocardiographic measurements in a regression equation for left ventricular mass. Intraobserver (r = 0.96, p less than 0.01) and interobserver (r = 0.89, p less than 0.01) variability were low. To anatomically validate the echographic formula for left ventricular mass, left ventricular measurements made at autopsy were inserted into the formula. Mass was then calculated and compared with the actual mass. There was a strong correlation between the calculated and the measured left ventricular mass (r = 0.89, p less than 0.01). Left ventricular mass was not statistically related to race, but it was strongly associated with gender (p less than 0.001). It was strongly correlated with height (r = 0.82 for males, r = 0.71 for females) and body surface area (r = 0.83 for males, r = 0.74 for females). Echocardiographic criteria for left ventricular hypertrophy in children and adolescents, based on the 95th percentile, for left ventricular mass, left ventricular mass corrected for body surface area and left ventricular mass corrected for height are, respectively: 184.9 g, 103.0 g/m2 and 99.8 g/m for males and 130.2 g, 84.2 g/m2 and 81.0 g/m for females.(ABSTRACT TRUNCATED AT 250 WORDS)

QRS areas improve the electrocardiographic interpretation of right ventricular hypertrophy

Right ventricular hypertrophy (RVH) is the most frequent abnormality in children with heart disease. We have developed a computer electrocardiogram (ECG) diagnosis program to evaluate new scalar electrocardiographic criteria for the diagnosis of this condition in children. The overall performance of our program was comparable to that of a pediatric cardiologist. Computer program diagnosis was correct in 93% of 60 individuals using standard criteria and in 97% using our newly developed area criteria. The cardiologist's ECG diagnosis in the same individuals was correct in 99%. The sensitivities of our two new criteria, the R/S area ratio in lead V1 and the R wave area in lead V1, were greater than currently used criteria for the diagnosis of RVH. Computer-derived electrocardiographic measurements, such as areas, can improve the accuracy of the ECG diagnosis of RVH.

Scalar, planar, and spatial measurements of the Frank vectorcardiogram in normal infants and children

Frank-lead vectorcardiograms (VCGs) were obtained from 1222 normal infants and children. By means of the Pipberger computer system, 176 different scaler and vector measurements obtained from each VCG were correlated with height, weight, race, sex, torso length, chest circumference, and chest diameters to determine the effect of anthropometric indices on the VCG wave forms. Because 5509 tests of statistical significance were performed, correlation coefficients and tests of statistical significance are reported only with p less than 0.001. Height, weight, torso length, and chest circumference show good correlation with QT interval, but these findings are reflective of the decrease in heart rate with age. The VCG does not show consistent correlations with constitutional variables when stratified by age, sex, or race. There were six instances of VCG parameters significantly greater in black children, and four instances of VCG parameters significantly greater in white children. All racial differences, while statistically significant, are small by clinical, hand measurement standards. There were 22 VCG values in boys which exceeded those in girls and only one VCG value in girls which exceeded those in boys. In the pediatric age group, racial differences in VCG wave forms are small and clinically insignificant. The Frank-lead system adequately corrects for constitutional variables in infants and children. Adequate evaluation of pediatric VCGs requires stratification of data according to age and sex.

The normal pediatric Frank orthogonal electrocardiogram: influence of weight, height and chest circumference

The influence of body weight, height and chest circumference on the pediatric Frank vectorcardiogram (VCG) was investigated in a population of 1317 normal infants, children and adolescents. Simple linear regression analysis showed that 94, 96 and 57 VCG variables were significantly correlated with weight, height and chest circumference, respectively. These numbers were reduced to 10, 18 and 6 VCG variables after a stepwise multiple correlation analysis. The relationship between the VCG and the somatic variables was also studied in ten different age/sex subgroups. Simple regression analysis showed a residual significant correlation between the VCG and all three somatic variables in each group. The multiple correlation analysis allowed us to define a minimum set of VCG variables, from one to six, which could explain all the variation produced by the somatic variables. The coefficient of multiple correlation between VCG and weight was the highest in babies 0 to 6 months old (R = 0.73). For height, the strongest correlation was found in females two to five years old (R = 0.76). In subjects older than two years of age, the correlation between chest circumference and VCG (R = 0.30 to 0.69) was weaker than between VCG and pediatric VCG after stratification for age and sex, especially in the youngest groups.

Racial differences in electrocardiograms and vectorcardiograms between black and white adolescents

In a previous study of 244 normal children, we detected higher leftward, posterior and inferior voltages in blacks than in whites in two groups: 6- to 10-year-old children and in 11- to 14-year-old boys; no difference was found in 3-to-5-year-old children, or 11- to 14-year-old girls. The purpose of this study was to determine if such race-related voltage differences are also present in 15- to 19-year-old adolescents. Biographic data, blood pressure and hemoglobin values, electrocardiogram (ECG), Frank vectorcardiogram (VCG) and echocardiogram were obtained in 59 normal 15- to 19-year-olds (28 blacks and 31 whites); 144 measured parameters and 57 computed variables were analyzed. Many sex-related differences (p less than 0.05 to 0.001) were seen in both races. R in leads I, AVL and V6, S in V1, and sum of SV1 and RV6 in the ECG and X to left, terminal X to right and Y inferior in the VCG were higher (p less than 0.05 to 0.01) in black males than in white males. However, no such differences (p greater than 0.05) were observed between black and white females. To understand the causes of these differences, comparison of the biographic data, blood pressure, hemoglobins and echocardiograms were made. The height, weight, body surface area, chest circumference, AP diameter of the chest, diastolic and systolic blood pressure and left ventricular (LV) dimension were similar (p greater than 0.1) in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)