QT Variability Index is Correlated with Autonomic Nerve Activity in Healthy Children.

The QT variability index (QTVI), which measures the instability of myocardial repolarization, is usually calculated from a single electrocardiogram (ECG) recording and can be easily applied in children. It is well known that frequency analysis of heart rate variability (HRV) can detect autonomic balance, but it is not clear whether QTVI is correlated with autonomic tone. Therefore, we evaluated the association between QTVI and HRV to elucidate whether QTVI is correlated with autonomic nerve activity. Apparently, healthy 320 children aged 0-7 years who visited Fujita Health University Hospital for heart checkup examinations were included. The RR and QT intervals of 60 continuous heart beats were measured, and the QTVI was calculated using the formula of Berger et al. Frequency analysis of HRV, including the QTVI analysis region, was conducted for 2 min and the ratio of low-frequency (LF) components to high-frequency (HF) components (LF/HF) and HF/(LF + HF) ratio was calculated as indicators of autonomic nerve activity. Then, the correlations between QTVI and these parameters were assessed. QTVI showed a significant positive correlation with LF/HF ratio (r = 0.45, p < 0.001) and negative correlation with HF/(LF + HF) ratio (r = -0.429, p < 0.001). These correlations remained after adjustment for sex and age. QTVI, which is calculated from non-invasive ECG and can detect abnormal myocardial repolarization, is significantly correlated with frequency analysis of HRV parameters. QTVI reflects autonomic nerve balance in children.

Exercise-induced asthma is associated with impaired quality of life among children with asthma in Japan.

BACKGROUND: Asthma is the most common chronic diseases in school-aged children in Japan. It is important to consider health-related quality of life (QoL) among children with chronic diseases when treatment decisions are made. METHODS: A school-based survey was conducted in randomly selected public schools in Tokyo by using a KINDL questionnaire for evaluating QoL and the international study of asthma and allergy on childhood (ISAAC) questionnaire, which is designed for comparing the asthma prevalence in various countries, from May to June in 2005. We recruited approximately 10% of the total children 6-7-years-old and 13-14-years-old living in Tokyo for sampling. RESULTS: Response rate of this questionnaire was 86% (22,645 children) in the 6-7-year-old group and 64% (12,879 children) in the 13-14-year-old group. Comparing asthmatics with non-asthmatics in the same age, QoL of children with asthma was significantly impaired. The severity of QoL of children with asthma was significantly impaired. QoL of children with exercise-induced asthma (EIA) were more significantly impaired than ones without EIA and showed lower scores in the categories of physical functioning, emotional and school activities than those without EIA. Of note, QoL was more impaired in the EIA-positive group among severe asthmatics, suggesting that QoL of children with even severe asthma could be improved when EIA is appropriately controlled. CONCLUSIONS: Existence of EIA among asthmatic children most strongly impairs their QoL. We should be more cautious about the management of EIA.

Clinical features of adult patients with Eisenmenger's syndrome in Japan and Korea.

BACKGROUND: There are few articles on mortality and morbidity of adult patients with Eisenmenger's syndrome (ES) in the current era when disease targeting therapy (DTT) has been available. METHODS AND RESULTS: 198 patients (a median age 35 years, 64% female) with ES who visited the 16 participating institutes in Japan and Korea from 1998 to 2009 were enrolled. Clinical data during adulthood were collected from each institutional chart and analyzed centrally. During a median follow-up of 8 years, 30 patients died including 14 sudden deaths. 89 patients took oral medication of DTT and clinical improvement was observed in 54 of them. However, survival rate in patients taking DTT was not different from those without (87% vs 84%, p=0.55). When the clinical data in between first and last clinic visits were compared in 85 patients, the patients with NYHA >/=III increased from 24% to 48% (p<0.001), SpO2 decreased from 89% to 85% (p=0.008) and hematocrit increased from 51.4% to 52.9% (p=0.04). Non-survivors had poorer NYHA function class, lower body weight (BW), lower body mass index (BMI), and higher serum level of Cr at the first visits than survivors. CONCLUSIONS: Long term survival and clinical status of adult patients with ES remains unsatisfactory even in the current era of DTT. Poor NYHA functional class, low BW, low BMI and high serum level of Cr were related to mortality. DTT therapy improved clinical status in many patients with Eisenmenger's syndrome, but no significant impact on survival could be shown.