Effects of cohort, genotype, variant, and maternal ß-blocker treatment on foetal heart rate predictors of inherited long QT syndrome.

AIMS: In long QT syndrome (LQTS), primary prevention improves outcome; thus, early identification is key. The most common LQTS phenotype is a foetal heart rate (FHR) < 3rd percentile for gestational age (GA) but the effects of cohort, genotype, variant, and maternal ß-blocker therapy on FHR are unknown. We assessed the influence of these factors on FHR in pregnancies with familial LQTS and developed a FHR/GA threshold for LQTS. METHODS AND RESULTS: In an international cohort of pregnancies in which one parent had LQTS, LQTS genotype, familial variant, and maternal ß-blocker effects on FHR were assessed. We developed a testing algorithm for LQTS using FHR and GA as continuous predictors. Data included 1966 FHRs at 7-42 weeks' GA from 267 pregnancies/164 LQTS families [220 LQTS type 1 (LQT1), 35 LQTS type 2 (LQT2), and 12 LQTS type 3 (LQT3)]. The FHRs were significantly lower in LQT1 and LQT2 but not LQT3 or LQTS negative. The LQT1 variants with non-nonsense and severe function loss (current density or ß-adrenergic response) had lower FHR. Maternal ß-blockers potentiated bradycardia in LQT1 and LQT2 but did not affect FHR in LQTS negative. A FHR/GA threshold predicted LQT1 and LQT2 with 74.9% accuracy, 71% sensitivity, and 81% specificity. CONCLUSION: Genotype, LQT1 variant, and maternal ß-blocker therapy affect FHR. A predictive threshold of FHR/GA significantly improves the accuracy, sensitivity, and specificity for LQT1 and LQT2, above the infant's a priori 50% probability. We speculate this model may be useful in screening for LQTS in perinatal subjects without a known LQTS family history.

Developmental trajectories at a high risk for childhood overweight/obesity.

BACKGROUND: The associations between developmental patterns (trajectories) in children and maternal factors have been widely investigated, but paternal effects on these trajectories are unclear. This study aimed to determine child and parental factors involved in developmental trajectories at high risk for causing adverse cardiovascular (CV) profiles in children. METHODS: We analyzed longitudinal anthropometric data from birth to the present and CV profiles of 1,832 healthy volunteers (51% girls) aged 3-15 years who participated in a nationwide study between July 2012 and January 2014. Six trajectory latent class growth models were developed using body mass index z- scores. Predictors for being in developmental trajectories at high risk for causing adverse CV profiles were determined by multivariate regression analysis. RESULTS: The mean±standard deviation number of anthropometric data points was 12±3 for both boys and girls. Among the six trajectories, the infantile onset and continual increase groups had significantly worse levels of many CV profiles than those in the remaining groups. Paternal overweight/obesity was an independent predictor for boys being in the infantile onset group and for girls being in the continual increase group. Additionally, maternal pre-pregnancy overweight/obesity in boys and maternal excessive gestational weight gain in girls were independent predictors for being in the infantile onset group. Having no sibling in boys and an older maternal age were independent predictors for being in the continual increase group. CONCLUSIONS: Interventions to prevent childhood obesity should include strategies that focus on fathers and mothers as well as those that focus on children with certain types of familial background.

Control of Heart Rate in Infant and Child Tachyarrhythmia With Reduced Cardiac Function Using Landiolol (HEARTFUL)　- Results of a Prospective, Multicenter, Uncontrolled Clinical Study.

BACKGROUND: The prospective Control of HEART rate in inFant and child tachyarrhythmia with reduced cardiac function Using Landiolol (HEARTFUL) study investigated the effectiveness and safety of landiolol, a short-acting ß1 selective blocker, in children.Methods and Results: Twenty-five inpatients aged ≥3 months to <15 years who developed supraventricular tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, and inappropriate sinus tachycardia) were treated with landiolol. The primary endpoint, the percent of patients with a reduction in heart rate ≥20% from the initial rate of tachycardia, or termination of tachycardia at 2 h after starting landiolol, was achieved in 12/25 patients (48.0%; 95% CI 28.4-67.6), which exceeded the predetermined threshold (38.0%). At 2 h after starting landiolol administration, heart rate had decreased by ≥20% in 45.8% (11/24) and recovery to sinus rhythm was achieved in 40.0% (6/15) of the patients. Adverse reactions (ARs) occurred in 24.0% (6/25) of patients, and the study was discontinued in 4.0% (1/25) of the patients; however, none of these ARs were considered serious. The most common AR was hypotension (20.0% [5/25] of patients). CONCLUSIONS: The HEARTFUL study has demonstrated the efficacy of landiolol, by reducing heart rate or terminating tachycardia, in pediatric patients with supraventricular tachyarrhythmias. Although serious ARs and concerns were not identified in this study, physicians should be always cautious of circulatory collapse due to hypotension.

Outcomes of hypertrophic cardiomyopathy in Japanese children: a retrospective cohort study.

There has been no multicenter study on the prognosis of pediatric hypertrophic cardiomyopathy (HCM) in Japan. Therefore, we conducted a retrospective multicenter observational study on the long-term survival rate in patients diagnosed with HCM under the age of 18 between 1990 and 2014. Twenty institutions participated. A total of 180 patients were identified. The median age at diagnosis was 5.8 years old and median duration of observation was 8.3 years. Although six patients (3%) deteriorated into the dilated phase of HCM, no patient received heart transplantation. Freedom from death at 1, 5, 10, and 20 years were 97%, 92%, 84%, and 80%, respectively. There were 26 deaths. Among them, 11 patients died suddenly, presumably due to arrhythmia, and 15 patients died of heart failure. The presence of heart failure symptoms and a greater cardiothoracic ratio were significant risk factors for heart failure-related death. There were no significant risk factors identified for arrhythmia-related death. In conclusion, the prognosis of pediatric HCM in Japan is good and similar to those reported in population-based studies in the United States and Australia. Significant risk factors for heart failure-related death were identified in pediatric patients with HCM in Japan.

Lung Ultrasound for Predicting the Respiratory Outcome in Patients with Bronchopulmonary Dysplasia.

OBJECTIVE: This study aimed to investigate the utility of lung ultrasound (LUS) with whole chest scanning for predicting respiratory outcomes in patients with bronchopulmonary dysplasia (BPD). STUDY DESIGN: We performed a prospective observational study. Preterm infants of less than 32 weeks' gestational age requiring oxygen therapy at 28 days of life were included. LUS was performed on day 28, at 36 weeks' postmenstrual age, and at the time of discharge. Each lung was divided into three regions by the anterior and posterior axillary lines and received an LUS score of 0 to 3 points; the total score was obtained by adding the six regional scores. The classification of BPD was determined based on the National Institute of Child and Human Development. The outcomes of this study were the development of moderate-to-severe BPD and the need for home oxygen therapy (HOT). RESULTS: We enrolled 87 patients; 39, 33, and 15 infants had mild, moderate, and severe BPD, respectively. The LUS score correlated with BPD severity and exhibited an improvement trend with time toward the point of discharge. LUS at 28 days of life predicted moderate-to-severe BPD with an area under the curve of 0.95 (95% confidence interval: 0.91-0.99) and HOT with an area under the curve of 0.95 (95% confidence interval: 0.81-1.0). CONCLUSION: LUS with whole chest scanning is useful for predicting respiratory outcomes in patients with BPD, as well as for understanding BPD severity or clinical improvement trends. KEY POINTS: · LUS predicts respiratory outcomes in patients with BPD.. · LUS indicates BPD severity.. · LUS can show clinical improvement with time..

Outcomes of Dilated Cardiomyopathy in Japanese Children　- A Retrospective Cohort Study.

BACKGROUND: There has been no nationwide survey on the prognosis of pediatric dilated cardiomyopathy (DCM) in Japan. Therefore, we designed this retrospective multicenter study to investigate the long-term survival rate in pediatric patients with DCM in Japan.Methods and Results:In this multicenter retrospective observational study, data were reviewed for 106 patients aged <18 years who had been diagnosed with DCM at any 1 of 18 Japanese institutions between 1990 and 2014. The median age at diagnosis was 2.0 years and the median duration of observation was 3.3 years. Most DCM patients were diagnosed because of symptoms of heart failure. On echocardiography, the median left ventricular end-diastolic dimension z score was 5.4 and fractional shortening was 0.10. Freedom from death or transplantation rates at 1, 3, 5, 10, and 20 years after diagnosis were 76%, 66%, 64%, 58%, and 43%, respectively. Freedom from death rates at 1, 5, 10, and 20 years after diagnosis were 81%, 75%, 72%, and 53%, respectively. The incidence of heart transplantation at 1, 5, 10, and 20 years after diagnosis was 6%, 15%, 20%, and 20%, respectively, suggesting that only 15% of patients in Japan underwent heart transplantation within 5 years of diagnosis. CONCLUSIONS: In Japan, the prognosis of pediatric DCM is poor and the rate of heart transplantation is low.

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.

Diagnostic value of P-waves in children with idiopathic restrictive cardiomyopathy.

Restrictive cardiomyopathy (RCM) is a rare myocardial disease with an impaired diastolic function and poor prognosis. Almost all RCM patients are reported to have abnormal P-waves due to atrial overloading. This study aimed to reveal the characteristics of the P-waves in RCM patients and to suggest the diagnostic index of RCM in children with a 12-lead electrocardiogram (ECG). We retrospectively investigated 17 ECGs of children with idiopathic RCM during the initial visit at 15 institutes in Japan between 1979 and 2013. The RCM group was divided into four groups based on the age (elementary school [ES] and junior high school [JHS] students) and inception of the diagnosis (abnormal ECG on school-heart-screening [e-RCM] and some cardiovascular symptoms [s-RCM]), the ES/e-RCM (n = 5), ES/s-RCM (n = 4), JHS/e-RCM (n = 4), and JHS/s-RCM (n = 4) groups. As an aged-match control group, school-heart-screening ECGs of 1st-grade ES students (16,770 students) and 1st-grade JHS students (18,126 students) from Kagoshima in 2016 were adopted. For a comparison between the groups, we used the effect size "Hedge's g" by calculating the mean and standard deviation of the two groups. An effect size of 0.8 (or above) had an overlap of 53% (or less). The effect sizes of the sum of the absolute values of the forward and backward amplitudes in lead V1 (P1 + P2 V1) was the largest, and the ES/e-RCM, ES/s-RCM, JHS/e-RCM, and JHS/s-RCM were 15.8, 22.1, 9.4, and 10.3, respectively. A P1 + P2 V1 > 200 µV was able to rule in all RCM patients, thus, we proposed 200 µV as the cutoff value for screening purposes. In conclusion, the P1 + P2 V1 in the school-heart-screening may be useful for detecting asymptomatic or early-stage RCM in school-age children.

Mothers with long QT syndrome are at increased risk for fetal death: findings from a multicenter international study.

BACKGROUND: Most fetal deaths are unexplained. Long QT syndrome is a genetic disorder of cardiac ion channels. Affected individuals, including fetuses, are predisposed to sudden death. We sought to determine the risk of fetal death in familial long QT syndrome, in which the mother or father carries the long QT syndrome genotype. In addition, we assessed whether risk differed if the long QT syndrome genotype was inherited from the mother or father. OBJECTIVE: This was a retrospective review of pregnancies in families with the 3 most common heterozygous pathogenic long QT syndrome genotypes in KCNQ1 (LQT1), KCNH2 (LQT2), or SCN5A (LQT3), which occur in approximately 1 in 2000 individuals. The purpose of our study was to compare pregnancy and birth outcomes in familial long QT syndrome with the normal population and between maternal and paternal carriers of the long QT syndrome genotype. We hypothesized that fetal death before (miscarriage) and after (stillbirths) 20 weeks gestation would be increased in familial long QT syndrome compared with the normal population and that the parent of origin would not affect birth outcomes. STUDY DESIGN: Our study was a multicenter observational case series of 148 pregnancies from 103 families (80 mothers, 23 fathers) with familial long QT syndrome (60 with LQT1, 29 with LQT2, 14 with LQT3) who were recruited from 11 international centers with expertise in hereditary heart rhythm diseases, pediatric and/or adult electrophysiology, and high-risk pregnancies. Clinical databases from these sites were reviewed for long QT syndrome that occurred in men or women of childbearing age (18-40 years). Pregnancy outcomes (livebirth, stillbirth, and miscarriage), birthweights, and gestational age at delivery were compared among long QT syndrome genotypes and between maternal vs paternal long QT syndrome-affected status with the use of logistic regression analysis. RESULTS: Most offspring (80%; 118/148) were liveborn at term; 66% of offspring (73/110) had long QT syndrome. Newborn infants of mothers with long QT syndrome were delivered earlier and, when the data were controlled for gestational age, weighed less than newborn infants of long QT syndrome fathers. Fetal arrhythmias were observed rarely, but stillbirths (fetal death at >20 weeks gestation) were 8 times more frequent in long QT syndrome (4% vs approximately 0.5%); miscarriages (fetal death at ≤20 weeks gestation) were 2 times that of the general population (16% vs 8%). The likelihood of fetal death was significantly greater with maternal vs paternal long QT syndrome (24.4% vs 3.4%; P=.036). Only 10% of all fetal deaths underwent postmortem long QT syndrome testing; 2 of 3 cases were positive for the family long QT syndrome genotype. CONCLUSION: This is the first report to demonstrate that mothers with long QT syndrome are at increased risk of fetal death and to uncover a previously unreported cause of stillbirth. Our results suggest that maternal effects of long QT syndrome channelopathy may cause placental or myometrial dysfunction that confers increased susceptibility to fetal death and growth restriction in newborn survivors, regardless of long QT syndrome status.

Co-Phenotype of Left Ventricular Non-Compaction Cardiomyopathy and Atypical Catecholaminergic Polymorphic Ventricular Tachycardia in Association With R169Q, a Ryanodine Receptor Type 2 Missense Mutation.

BACKGROUND: Left ventricular non-compaction (LVNC) is a cardiomyopathy characterized by prominent trabeculae and intertrabecular recesses. We present the cases of 3 girls with the sameryanodine receptor type 2(RYR2) mutation who had phenotypes of both catecholaminergic polymorphic ventricular tachycardia (CPVT) and LVNC .Methods and Results:Clinical characteristics and genetic background of the 3 patients were analyzed retrospectively. Age at onset was 5, 6, and 7 years, respectively. Clinical presentation included syncope during exercise in all 3 patients and cardiac arrest in 2 patients. LVNC diagnosis was confirmed on echocardiography according to previously defined criteria. Exercise stress testing provoked ventricular arrhythmia in two of the patients. Beta-blockers (n=3) and flecainide (n=2) were given, and an implantable cardioverter defibrillator was used in 1 patient. Genotyping identified the sameRYR2-R169Q missense mutation and no other CPVT- or LVNC-related gene mutations. Functional analysis of the mutation using HEK293 cells with single-cell Ca2+imaging and [3H]ryanodine binding analysis, indicated a gain of function: a reduced threshold for overload-induced Ca2+release from the sarcoplasmic reticulum and increased fractional Ca2+release. CONCLUSIONS: The rare association of LVNC and CPVT phenotypes withRYR2mutations is less likely to be coincidental. Screening for life-threatening arrhythmias using exercise or pharmacologic stress tests is recommended in LVNC patients to prevent sudden cardiac death in those with preserved LV function.

The impact of right bundle branch block on right ventricular size and function assessed by three-dimensional speckle-tracking echocardiography.

To determine the influence of right bundle branch block (RBBB) on right ventricular (RV) size and function, we investigated the association between complete RBBB (CRBBB) and RV volume, function, and dyssynchrony by three-dimensional echocardiography. In this retrospective, cross-sectional study, 103 consecutive patients with adequate three-dimensional echocardiographic images were divided into the CRBBB, middle-range QRS, and narrow QRS group. RV volumetric and functional data were compared between the three groups. Among the 103 patients (44.8 ± 18.7 years, 50 men), the CRBBB group comprised 26 (25%) patients and the middle-range QRS group comprised 48 (47%). The CRBBB group showed a significant contraction delay in the RV inlet free wall and outflow tract; larger RV end-diastolic and systolic volume index (RV-EDVI, RV-ESVI); and lower RV systolic function. On dividing the CRBBB patients into two (with or without mechanical dyssynchrony), those with RV dyssynchrony showed larger RV-EDVI (121 ± 45 vs. 85 ± 25 mL/m2, P = 0.019) and RV-ESVI (93 ± 42 vs. 56 ± 20 mL/m2, P = 0.009) and smaller RV ejection fraction (24 ± 11 and 34 ± 11%, P = 0.026) than those without RV dyssynchrony. RV dyssynchrony in CRBBB patients might have an adverse effect on RV volume and function. Three-dimensional speckle-tracking echocardiography could provide additional and beneficial data during assessment of RV dyssynchrony.

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.

Multivariate analysis of TU wave complex on electrocardiogram in Andersen-Tawil syndrome with KCNJ2 mutations.

BACKGROUND: The exact differences between the TU wave complex of ATS1 and that of healthy individuals remain to be investigated. We sought to characterize the TU wave complex of Andersen-Tawil syndrome type 1 (ATS1) using high frequency electrocardiogram (ECG) data. METHODS: Electrocardiograms were recorded as time series data with a 2 kHz frequency ECG amplifier in 13 patients with ATS1 (positive for KCNJ2 mutation, ATS1 group) and age-matched healthy individuals (control group). Conventional ECG parameters were measured, and principal component analysis (PCA) and independent component analysis (ICA) were applied to the TU wave complex. RESULTS: Time from T peak (Tp) to U peak (Up), time from bottom (B) to Up, and time from B to U end (BUe, U duration) (0.232 ± 0.018 vs. 0.165 ± 0.017, p < .0001), where B is the lowest point between T and U waves, were all longer in the ATS1 group than the control group. Multivariate logistic regression analysis revealed that BUe could completely differentiate the two groups. PCA ratios in the ATS1 group were significantly larger than the control group (26.5 ± 12.3 vs. 10.4 ± 6.2, p = .0005). ICA revealed 1 or 2 U-wave-specific independent components (ICs) that exclusively comprise the U wave in ATS1, whereas U waves in the control group were composed of some ICs that also comprised T waves. CONCLUSIONS: U-wave-related temporal parameters, particularly BUe, and the existence of U-wave-specific ICs, extracted in the ICA, are useful for differentiation of U waves in ATS1 from those in healthy individuals.

Promoting physical activity through walking to treat childhood obesity, mainly for mild to moderate obesity.

BACKGROUND: There are no randomized controlled trials examining the effect of walking on childhood obesity. METHODS: A randomized controlled trial was conducted between August 2014 and April 2015 in Japan. Elementary school children aged 6 to 12 years with a percentage overweight (%OW) of ≥20% were recruited. One hundred and ninety children wanted to participate in the program, and all were accepted. After viewing a video that promoted physical activity through walking, participants were randomly assigned to three groups: walking (≥10 000 steps on school holidays), limiting screen time (<90 min on weekdays and <150 min on school holidays), and a control group (no intervention). The primary outcome was a decrease in %OW after 3 months' intervention. Per protocol analysis was performed using 156 participants who fulfilled the inclusion criteria of a %OW ≥20%. RESULTS: The mean %OW was 35 ± 7% before intervention. The mean reduction in %OW after intervention in the walking (n = 59), limiting ST (n = 46), and control (n = 51) groups were -4.06 ± 4.84, -1.97 ± 4.62, and -1.81 ± 3.64 percentage points, respectively. Reduction in %OW was significantly larger in the walking group than in the control group: adjusted mean difference, -2.18 percentage points (95% confidence interval, -3.85 to -0.52), P = 0.002. The intervention in children also had favorable effects on the lifestyles of their parents. The intention-to-treat analysis of all 190 participants showed comparable results. CONCLUSION: Promoting physical activity through walking on school holidays may be an additional strategy for treating elementary school children with obesity.

Structural relation between the superior vena cava and pulmonary veins in patients with atrial fibrillation.

The superior vena cava (SVC) is a main source of non-pulmonary vein (PV) ectopies that initiate atrial fibrillation (AF). Although the critical role of structural remodeling of the left atrium (LA) in the occurrence of AF was extensively investigated by atrial voltage mapping, that of PVs and the SVC has been less explored. Study subjects comprised 47 patients undergoing catheter ablation of lone AF. During sinus rhythm, PV, SVC, and atrial voltage maps were acquired, and sleeve length of each PV and SVC was determined by an electroanatomical mapping system. The sleeves of the superior PVs were significantly longer than those of the inferior PVs (left superior PV (LSPV): 21 ± 5, left inferior PV: 14 ± 4, right superior PV (RSPV): 19 ± 5, right inferior PV: 15 ± 5, and SVC: 23 ± 10 mm, p < 0.0001). The LSPV sleeve was longer in men than in women (22 ± 6 vs. 19 ± 4 mm, p < 0.05). The sleeve length in the LSPV correlated positively with the body surface area (BSA) (p = 0.003, R = 0.42). Of note, there was a significant correlation in sleeve length between the RSPV and SVC (p < 0.0001, R = 0.64). In conclusion, not right- but left-sided PV sleeves were associated with the BSA of the patients, whereas a structural relation between the right-sided PVs and the SVC was implied based on sleeve mapping. This novel finding may provide mechanistic implications for the development of AF in future studies.

Prenatal diagnosis of congenital absence of aortic valve associated with restrictive foramen ovale: Hemodynamic features and clinical outcome.

We present the case of a fetus with absent aortic valve (AAV), mitral regurgitation (MR), and restrictive foramen ovale (FO) who survived in utero but died of severe hypoxia after birth. We reported previously two cases of "inverse circulatory shunt" in AAV with MR, that is, blood from the ascending aorta flowing into the left ventricle through aortic regurgitation, to the left atrium due to MR, to the right atrium through FO, to the right ventricle, then to the pulmonary arteries, and to the ascending aorta through the ductus. In the present case, restrictive FO prevented inverse circulatory shunt, but resulted in postnatal death.

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.

Persistent QT Prolongation in a Child with Gitelman Syndrome and SCN5A H558R Polymorphism.

Gitelman syndrome (GS) is an inherited renal tubular disorder characterized by hypokalemic metabolic alkalosis, hypomagnesemia, and low urinary calcium excretion. While it is considered a benign disease, severe ventricular arrhythmia and sudden cardiac death related to the prolongation of the QT interval have been reported in rare cases. Herein we report a 13-year-old girl with GS who presented with persistent prolongation of the QT interval, even after being treated for hypokalemia and hypomagnesemia. Genetic analysis identified SCN5A H558R polymorphism, which modulates the function of myocardial sodium channel, and SLC12A3 A588V mutation, which causes GS. The SCN5A polymorphism and GS-related electrolyte disturbance might have contributed to the persistent QT prolongation in this patient. Although no ventricular arrhythmias were recorded in this case, careful cardiac surveillance should be applied for avoiding life-threatening cardiac events.

Endothelial Dysfunction of Conduit Arteries in Patients with Repaired Coarctation of the Aorta.

Adult patients with repaired coarctation of the aorta (r-CoA) show high prevalence of late hypertension, but the exact mechanisms of this phenomenon are unknown. Endothelial dysfunction has been implicated in this paradoxical hypertension. We evaluated the endothelial function of both conduit and resistance arteries by using flow-mediated dilation (FMD) and digital peripheral artery tonometry (PAT).Seventeen patients with r-CoA and one patient with repaired interrupted aortic arch (r-CoA group) aged 22.0 ± 6.9 years (5 females) underwent FMD of the right brachial artery, PAT of the right finger, blood marker tests, ambulatory blood pressure monitoring, echocardiography, carotid ultrasonography, and brachio-ankle pulse wave velocity measurement. The median age at aortic arch reconstruction was 2.0 months (interquartile range: 15 days to 7.0 years). Results were compared with 17 age-matched healthy subjects (control group).Eight (44%) patients of the r-CoA group were hypertensive (5 received antihypertensive drugs). Patients in the r-CoA group showed significantly lower FMD (3.8 ± 1.5 versus 6.6 ± 2.5%, P < 0.001), larger intima-media thickness (0.63 ± 0.17 versus 0.47 ± 0.09 mm, P = 0.001), and higher left ventricular mass index (91.4 ± 24.6 versus 73.4 ± 17.3 g/m2, P = 0.017) than those in the control group. There were no significant differences in PAT (refractory hyperemia index, 1.86 ± 0.43 versus 1.99 ± 0.59, P = 0.48) and brachio-ankle pulse wave velocity between the two groups.Vascular dysfunction in r-CoA patients, particularly endothelial dysfunction, tends to occur more significantly in conduit arteries than in resistance arteries.