Electrocardiographic Diagnosis of Hypertrophic Cardiomyopathy in the Pre- and Post-Diagnostic Phases in Children and Adolescents.

BACKGROUND: The usefulness of electrocardiographic (ECG) voltage criteria for diagnosing hypertrophic cardiomyopathy (HCM) in pediatric patients is poorly defined.Methods and Results:ECGs at the 1st grade (mean [±SD] age 6.6±0.3 years) were available for 11 patients diagnosed with HCM at around the 7th grade (13.2±0.3 years). ECGs were available for another 64 patients diagnosed with HCM in the 1st (n=15), 7th (n=32), and 10th (n=17) grades. Fifty-one voltage criteria were developed by grade and sex using 62,841 ECGs from the general population. Voltage criteria were set at the 99.95th percentile (1/2,000) point based on the estimated prevalence of childhood HCM (2.9 per 100,000 [1/34,483]) to decrease false negatives. Conventional criteria were from guidelines for school-aged children in Japan. Of 11 patients before diagnosis, 2 satisfied conventional criteria in 1st grade; 5 (56%) of the remaining 9 patients fulfilled 2 voltage criteria (R wave in limb-lead I [RI]+S wave in lead V3 [SV3] and R wave in lead V3 [RV3]+SV3). Robustness analysis for sensitivity showed RV3+SV3 was superior to RI+SV3. For all patients after diagnosis, RI+SV4 was the main candidate. However, conventional criteria were more useful than voltage criteria. CONCLUSIONS: Early HCM prediction was possible using RV3+SV3 in >50% of patients in 1st grade. Voltage criteria may help diagnose prediagnostic or early HCM, and prevent tragic accidents, although further prospective studies are required.

A significance of school screening electrocardiogram in the patients with ventricular noncompaction.

Left ventricular noncompaction (LVNC) is a hereditary cardiomyopathy and is associated with high morbidity and mortality. However, the role and significance of school screening for LVNC have not been fully elucidated. In this multicenter, retrospective cohort study, a total of 105 children with LVNC were included from 2000 to 2017. At the initial presentation, 44 patients (41.9%) were diagnosed by school screening. One (1.0%) patient underwent heart transplantation and four (3.8%) patients died during the study. Electrocardiogram data showed a high prevalence of fragmented QRS (33.4%) and J wave (15.7%). Treatments were needed in eight (18.2%) patients who were detected by school screening. The multivariable proportional hazards model showed T-wave abnormality on electrocardiogram in first graders was independent risk factors for major adverse cardiac events (odds ratio 4.94, p value = 0.0007). Moreover, dilation of the left atrium on chest X-ray and low ejection fraction on echocardiogram at the initial treatment were independent risk factors for treatment (odds ratio 1.7 × 107 and 22.3, p = 0.0362 and 0.0028, respectively). This study is the first report focusing on school screening in a large pediatric cohort with LVNC. With the use of abnormalities in electrocardiogram, school screening may be a good detector of and predictor for LVNC.

Standard Values and Characteristics of Electrocardiographic Findings in Children and Adolescents.

BACKGROUND: Reference values and the characteristics of the electrocardiographic (ECG) findings using a large number of subjects are lacking for children and adolescents.Methods and Results:A total of 56,753 digitally stored ECGs of participants in a school-based ECG screening system were obtained between 2006 and 2009 in Kagoshima, Japan. Each ECG was manually reviewed by 2 pediatric cardiologists and only ECGs with sinus rhythm were included. A final total of 48,401 ECGs from 16,773 1st (6 years old, 50% girls), 18,126 7th (12 years old, 51% girls), and 13,502 10th graders (15 years old, 52% girls) were selected. ECG variables showed differences in age and sex. However, the effects of age and sex on ECG variables such as the PQ interval, QRS voltage, and STJ segment were also different. The 98th percentile values of well-known surrogate parameters for ventricular hypertrophy in the present study were much higher than the conventional criteria. CONCLUSIONS: The present study of a large number of pediatric subjects showed that the effects of age and sex on ECG parameters are different, and that criteria for ventricular hypertrophy should be newly determined by age and sex. We have developed reference data for STJ segment elevation for children and adolescents. These findings are useful for creating guidelines and recommendations for interpretation of pediatric ECG.

Environmental risk factors for sudden infant death syndrome in Japan.

While the prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, this decline has plateaued recently. Strategies are needed to resume the constant decrease of SIDS in Japan. A prospective electrocardiographic screening program for infants was performed between July 2010 and March 2011. Parents of 4319 infants were asked about environmental factors related to SIDS through questionnaires at a one-month medical checkup and one year. Parental awareness of prone position, smoke exposure, and breast feeding as environmental factors were 81.4 %, 69.0 %, and 47.8 %, respectively. The prevalence of laying infants exclusively in a supine position was 96.7 %. At the one-month medical checkup, smoking prevalence was 41.7 % in fathers and 2.1 % in mothers. Maternal smoking prevalence was significantly increased at one year after (p < 0.001). Multivariate regression analysis showed that risk factors for new or continued maternal smoking habits were maternal smoking habits at one month (p < 0.001), paternal smoking habits one year later (p < 0.001), and younger maternal age (p = 0.02). CONCLUSION: Most parents already avoid laying infants in the prone position, and parental smoking is still a SIDS risk concern in Japan. Smoking cessation programs should be further implemented for parents to decrease risks of SIDS in Japan. What is Known: • The prevalence of sudden infant death syndrome (SIDS) has decreased worldwide, however, this decline has plateaued recently. What is New: • Most infants were laid sleeping in the supine position (96.7 %) and were fed breast milk or a mix of expressed milk and formula (92.7 %), and 2.1 % of mothers smoked at the one-month medical checkup. • Maternal smoking prevalence significantly increased from the one-month medical checkup to one year later, and smoking mothers were more likely to feed infants by formula rather than breast milk. • Independent risk factors for new or continued maternal smoking habits included younger maternal age, maternal smoking habits at one month, and paternal smoking habits one year later.

Electrocardiographic screening of 1-month-old infants for identifying prolonged QT intervals.

BACKGROUND: Neonatal electrocardiographic screening is used to screen infants with prolonged QT intervals, as previously shown in whites. However, this procedure needs to be confirmed in other ethnic groups. METHODS AND RESULTS: In 8 areas in Japan, an ECG was recorded in 4285 infants at 1-month medical checkup. A prospective study showed that a provisional criterion of QTc≥470 ms was appropriate for infants. To assess the validity of the criterion, all infants with a QTc between 460 and 470 ms were followed up. Five infants had a QTc≥470 ms. Four infants were diagnosed with prolonged QT intervals from follow-up ECGs. Four infants showed no symptoms and did not have a family history of long-QT syndrome. Two infants showed progressive prolongation of QT intervals, and medication was started. Genetic testing was performed in 3 of 4 infants with prolonged QT intervals, and it revealed a KCNH2 mutation (3065 delT, L1021fs+34X) in 1 infant. One infant with a QTc≥470 ms and 2 infants with a QTc between 460 and 470 ms showed a decline in their QTc values during follow-up. The study screened another infant with Wolff-Parkinson-White syndrome who was diagnosed with noncompaction before symptoms appeared. CONCLUSIONS: Neonatal electrocardiographic screening can identify infants likely to be affected by long-QT syndrome in the Japanese population, as already shown in whites. This screening may also be useful in identifying other important cardiac diseases.

[Acute type a aortic dissection operated in childhood; report of a case].

A 12-year-old boy without any previous history and risk factors of cardiovascular disease presented to the emergency room with persisting general fatigue, bilateral shoulder pain and facial pallor. He was diagnosed as acute type A aortic dissection with cardiac tamponade by ultrasonic cardiogram (UCG) and computed tomography (CT) imaging, and the emergency surgery was indicated. He underwent hemiarch replacement because his aorta diameter was quite small but grafting as a large vascular prosthesis as possible was necessary in consideration of the growth. His postoperative course was uneventful and good, and he was discharged from our hospital in day 21 postoperatively. Acute aortic dissection in childhood is very rare but life-threatening. We should consider the particularity of children and make early diagnosis and treatment appropriately.

Clinical characteristics and genetic background of congenital long-QT syndrome diagnosed in fetal, neonatal, and infantile life: a nationwide questionnaire survey in Japan.

BACKGROUND: Data on the clinical presentation and genotype-phenotype correlation of patients with congenital long-QT syndrome (LQTS) diagnosed at perinatal through infantile period are limited. A nationwide survey was conducted to characterize how LQTS detected during those periods is different from that in childhood or adolescence. METHODS AND RESULTS: Using questionnaires, 58 cases were registered from 33 institutions. Diagnosis (or suspicion) of LQTS was made during fetal life (n=18), the neonatal period (n=31, 18 of them at 0 to 2 days of life), and beyond the neonatal period (n=9). Clinical presentation of LQTS included sinus bradycardia (n=37), ventricular tachycardia/torsades de pointes (n=27), atrioventricular block (n=23), family history of LQTS (n=21), sudden cardiac death/aborted cardiac arrest (n=14), convulsion (n=5), syncope (n=5), and others. Genetic testing was available in 41 (71%) cases, and the genotype was confirmed in 29 (71%) cases, consisting of LQT1 (n=11), LQT2 (n=11), LQT3 (n=6), and LQT8 (n=1). Ventricular tachycardia/torsades de pointes and atrioventricular block were almost exclusively observed in patients with LQT2, LQT3, and LQT8, as well as in those with no known mutation. In LQT1 patients, clues to diagnosis were mostly sinus bradycardia or family history of LQTS. Sudden cardiac death/aborted cardiac arrest (n=14) was noted in 4 cases with no known mutations as well as in 4 genotyped cases, although the remaining 6 did not undergo genotyping. Their subsequent clinical course after aborted cardiac arrest was favorable with administration of beta-blockers and mexiletine and with pacemaker implantation/implantable cardioverter-defibrillator. CONCLUSIONS: Patients with LQTS who showed life-threatening arrhythmias at perinatal periods were mostly those with LQT2, LQT3, or no known mutations. Independent of the genotype, aggressive intervention resulted in effective suppression of arrhythmias, with only 7 deaths recorded.

Is the chronotropic index applicable to children and adolescents?

BACKGROUND: The aim of the present study was to investigate whether the chronotropic index (CRI) is independent of age, sex, stage of exercise testing, functional capacity and resting heart rate in children, as it is in adult populations. METHODS AND RESULTS: A total of 129 normal children and adolescents underwent maximal treadmill exercise testing according to the Bruce protocol. Submaximal chronotropic response was assessed by the CRI at the end of stages 1, 2, 3, and 4 of Bruce treadmill exercise testing. The CRI assessed at each exercise stage was independent of sex, maximal oxygen uptake and resting heart rate. The CRI was independent of age when measured at stages 3 and 4 in boys and at stage 4 in girls, but was weakly correlated with age when measured at stages 1 and 2 in boys and at stages 1, 2 and 3 in girls. There was a significant effect of exercise intensity on the CRI: multiple comparisons revealed that, in girls, CRI assessed at stage 1 was greater than that assessed at stage 4. Also, lower exercise stages resulted in rather large variations in the measurement. CONCLUSION: The results essentially confirm the potential applicability of the CRI for children and adolescents, although care should be taken in evaluating measurements of the CRI in the early stages of exercise testing to avoid misinterpretation of the results.

Nutritional state and growth and functional maturation of the brain in extremely low birth weight infants.

OBJECTIVE: It is well-known that an undernutritional status influences central nervous system development in the fetal and early neonatal period. On the other hand, the maturational delay of the central nervous system is reflected as dysmature pattern (DMP) in the neonatal background electroencephalograph (EEG). Therefore, we hypothesized that the postnatal nutritional status influenced electrophysiologic maturation in extremely low birth weight infants (ELBWIs). METHODS: ELBWIs between 24 and 27 weeks of gestational age who were admitted to Ogaki Municipal Hospital NICU from April 1997 to December 2000 were considered eligible. From the condition of enteral feeding, infants were divided into 2 groups: 1). normal nutritional group (group N), where enteral feeding had been established (100 mL/kg/d) by 3 weeks after birth; 2). undernutritional group (group U), where enteral feeding had not been established by 3 weeks after birth or was discontinued because of clinical problems. Weekly average body weight and head circumference gains were evaluated as nutritional status. EEG records were performed every 2 to 4 weeks until postnatal 15 weeks of age. DMP was defined as the appearance of immature EEG patterns for postconceptional age. RESULTS: Twenty-one infants had serial EEG recordings; 11 infants belonged to group N and 10 infants to group U. Gestational age, birth weight, and head circumference at birth were not different between the 2 groups. The body weight of group N was significantly heavier than that of group U after 5 postnatal weeks. Similarly, the head circumference of group N was larger than that of group U after 6 weeks of postnatal age. Nine infants demonstrated DMPs. One infant belonged to group N and 8 to group U. DMPs were significantly more frequently found in group U than group N (80% vs 9%). In 6 of the 9 cases, the DMPs lasted until 38 to 40 weeks of postconceptional age. Five of the 6 infants with persistent DMPs suffered from severe undernutritional conditions. The other, who belonged to group N, was treated with corticosteroid for chronic lung disease. In 3 cases, DMPs were observed transiently and their undernutritional status was not so severe. CONCLUSIONS: Our study indicated that a postnatal undernutritional condition was associated with DMPs in ELBWIs. Undernutritional status may affect electrophysiologic maturation.

Simple exponential regression model to describe the relation between minute ventilation and oxygen uptake during incremental exercise.

The physiological significance of an exponential regression model between minute ventilation (VE) and oxygen uptake (VO2) during incremental exercise was examined. Thirty-eight subjects, including 12 patients with chronic heart failure, participated in cardiopulmonary exercise testing on a bicycle ergometer. The equation VE = a e(bVO2), where a and b are parameters, was used to describe the relation between VE and VO2 during incremental exercise. Arterialized blood gas analysis was measured before and during exercise. The correlation coefficient of the regression model was high (r = 0.97 +/- 0.02). Parameter a negatively correlated with the arterial partial pressure of carbon dioxide during exercise (r = -0.44, p < 0.01), and positively correlated with peak VO2 (r = 0.47, p < 0.01). Parameter b negatively correlated with peak VO2 (r = -0.86, p < 0.01) and positively correlated with the dead space to tidal volume ratio (r = 0.68, p < 0.01). The regression model, as well as parameters a and b, is physiologically useful in expressing metabolic response to exercise. This model, a specific solution to the differential equation dVE/dVO2 = bVE, implies that the more a subject breathes, the greater is the increment in ventilation needed to meet a further increment of metabolic demand.