Correlation among the heart rate variability indices in healthy children and those with atrial septal defect.

OBJECTIVES: Most researchers use the time domain and spectral analysis in the assessment of heart rate variability (HRV), while others use either the time or frequency domain measures. In this study, we investigated the presence of correlation between the time and frequency domain indices of HRV in normal healthy children and in patients with atrial septal defect (ASD). STUDY DESIGN: A total of 60 children, 28 with ASD and 32 healthy children, were recruited. Time domain measures and frequency domain measures were analyzed from the 24-hour Holter ECG records. Correlation between time domain measures and frequency domain measures as well as correlation within the time domain measures was computed in each group. RESULTS: There was a positive correlation among all the measurements except the low- (LF) and high- (HF) frequency (LF/HF) ratio which was negatively correlated. The degree of correlation was stronger in some variables and weak in others. CONCLUSION: We have shown that time domain measures are correlated with frequency domain measures in both ASD patients and in healthy children. Some of these indices are so strongly correlated with each other that they can be used interchangeably.

Heart rate variability in patients with atrial septal defect and healthy children.

OBJECTIVE: Heart rate variability (HRV) measures are altered in various cardiac and non-cardiac situations in children. The autonomic nervous system is assumed to have a role in the pathophysiology of atrial septal defect (ASD). In this study, we evaluated the autonomic system by measuring HRV in children with ASD. METHODS: Twenty-eight patients with ASD and 32 healthy children (mean ages: 6.6±2.1 years and 6.4±2.2 years, respectively) were enrolled in the study. Twenty-four-hour ambulatory electrocardiographic recordings were obtained and the seven time-domain (SDNN, SDANN, rMSSD, SD, SDNN index, PNN50, and mean RR) and four frequency-domain (VLF, LF, HF, and LF/HF ratio) indices of HRV were analyzed. RESULTS: A significant decrease in calculated HRV variables was observed in children with ASD as compared to controls. The HRV alteration was found in both time-domain and frequency-domain parameters. CONCLUSIONS: Our results indicate that HRV is decreased in children with ASD, which implies parasympathetic withdrawal and sympathetic predominance.

Assessment of cardiac parameters in evaluation of cardiac functions in patients with thalassemia major.

The aim of the study was to evaluate cardiac function and early cardiac dysfunction of patients followed as thalassemia major. In this study, the authors compared 100 patients, diagnosed as thalassemia major with mean age 11.84 ± 4.35, with 60 healthy control subjects at the same age between 2008 and 2011. Early diagnosis of iron overload that may occur after repeated transfusions is important in this patient group. To detect early iron accumulation, the authors compared ferritin with the echo findings, the 24-hour Holter, and cardiac magnetic resonance imaging (MRI) T2* values in the patients of same age and sex, treated with chelators, without heart failure, nonsplenectomized, and do not differ in the presence of hepatitis C. Ferritin levels, left ventricular systolic functions (ejection fraction [EF], shortening fraction [SF]), left ventricular measurements, left ventricular diastolic functions, T2* image on cardiac magnetic resonance, heart rate variables in 24 hours, and Holter rhythm were evaluated to show the early failure of cardiac functions. In this study the authors confirmed that iron-related cardiac toxicity damages electrical activity earlier than myocardial contractility. Left ventricular diastolic diameter (LVDd), left ventricular mass (LVM), and LV systolic diameter (LVDs) levels were significantly higher in the patient group with ectopia. Patients with ectopia are the ones in whom LVM and LVDd are increased. In thalassemia major patients with ectopia, LF/HF ratio was markedly increased, QTc dispersion was clearly found higher in patients with ectopia rather than nonectopic patients. The standard deviation all normal RR interval series (SDNN) was found clearly lower in thalassemia major group with ectopia than control group because it is assumed that increase in cardiac sympathetic neuronal activity is related to exposure to chronic diastolic and systolic failure.

QT dispersion and cardiac involvement in patients with juvenile idiopathic arthritis.

Juvenile idiopathic arthritis (JIA) is the commonest cause of chronic inflammatory arthritis in childhood. Cardiac involvement as pericarditis, myocarditis and valvular disease is known to occur in patients with JIA (JIA), as it does in adults with rheumatoid arthritis. There are, however, few descriptions concerning systolic and diastolic functions of the left ventricle (LV) in children with JIA. QT dispersion (QTd) is simple noninvasive arrhythmogenic marker that can be used to assess homogeneity of cardiac repolarization and which has not been studied in JIA patients before. A recent study found that rheumatoid arthritis patients had an abnormally longer QTd and corrected QT (cQTd) dispersion, markers for ventricular arrhythmogenicity. This study assessed QTd and cQTd and their relation with systolic and diastolic function of the LV in a group of children with JIA. We performed electrocardiography and Doppler echocardiography on patients and controls. Maximum QT (QTmax), minimum QT (QTmin), QTd, corrected QT, maximum corrected QT (cQTmax), minimum corrected QT (cQTmin) and cQTd intervals were measured from standard 12-lead electrocardiography. No statistically significant differences were found between the groups in QTd and cQTd. Among the diastolic parameters, increased late flow velocity, decreased early flow velocity and prolonged isovolumic relaxation time reflected an abnormal relaxation form of diastolic dysfunction. During 12 months of follow-up, no ventricular arrhythmias were documented in either group.

P wave dispersion in juvenile idiopathic arthritis patients with diastolic dysfunction.

OBJECTIVE: Cardiac involvement as pericarditis, myocarditis and valvular disease is common in juvenile idiopathic arthritis (JIA). However, there are few studies concerning systolic and diastolic functions of the left ventricle in children with JIA. P wave dispersion is a sign for the prediction of atrial fibrillation. A recent study found that rheumatoid arthritis patients had an abnormally high P wave duration and P wave dispersion, markers for supraventricular arrhythmogenicity. In this study, we aimed to evaluate P wave dispersion and its relation with diastolic dysfunction of the left ventricle in patients with JIA. METHODS: We performed electrocardiography and Doppler echocardiography on patients and controls. Maximum and minimum P wave duration were obtained from electrocardiographic measurements. P wave dispersion defined as the difference between maximum and minimum P wave duration was also calculated. FINDINGS: No statistically significant differences were found between the patients and controls in minimum, maximum P wave duration and P wave dispersion. Among the diastolic parameters in patients group, increased late flow velocity, decreased early flow velocity and prolonged isovolumic relaxation time reflected diastolic dysfunction. CONCLUSION: During 12 months of follow-up, no supraventricular arrhythmias were documented in JIA with diastolic dysfunction. JIA with diastolic dysfunction has normal atrial conduction parameters and therefore seemingly do not have an increased risk of atrial fibrillation.

QT dispersion and cardiac involvement in children with Familial Mediterranean fever.

Familial Mediterranean fever is a hereditary disease characterised by recurrent and self-terminated attacks of fever and polyserositis. An earlier study found that adult patients of Familial Mediterranean fever had an abnormally longer QT dispersion and corrected QT dispersion, markers for ventricular arrhythmogenicity. QT dispersion is a simple non-invasive arrhythmogenic marker that can be used to assess homogeneity of cardiac repolarisation; however, it has not been studied in children with Familial Mediterranean fever before. The aim of this study was to assess QT dispersion and corrected QT dispersion, and their relationship with systolic and diastolic function of the left ventricle in a group of children with Familial Mediterranean fever. We performed electrocardiography and Doppler echocardiography on patients and controls. Maximum QT, minimum QT, QT dispersion, corrected QT, maximum corrected QT, minimum corrected QT, and corrected QT dispersion intervals were measured from standard 12-lead electrocardiography. No statistically significant differences were found between the groups in QT dispersion, corrected QT dispersion, and systolic-diastolic function of the left ventricle parameters. During the 12 months of follow-up, no ventricular arrhythmias were documented in either group.