Hyperuricemia in an infant with Taussig-Bing anomaly and interruption of the aortic arch

Comparison of tissue Doppler imaging with MRI t2* and 24-hour rhythm holter heart rate variability for diagnosing early cardiac impairment in thalassemia major patients

OBJECTIVES

Cardiology follow up is important in thalassemia major patients. The object of this study is to define parameters which can be used in the early detection of cardiac impairment.

MATERIAL AND METHODS

Forty seven beta thalassemia major patients (mean age 16.3 ± 4.47 years; 22 boys, 25 girls) whose left ventricular systolic functions were normal and a healthy control group of fifty age and gender matched children were included in the study. M-mode echocardiographic measurements, systolic and diastolic functions with PW and tissue Doppler and heart rate variabilities (HRVs) were compared between the two groups. The patients were also grouped according to MRT2*, ferritin and left ventricular diastolic diameters (LVDds) to compare the echocardiographic and Holter parameters among them.

RESULTS

None of the children in the study group had symptomatic congestive heart failure. PW Doppler late diastolic forward flow in pulmonary artery was higher in the thalassemia group when compared with the control group (P = 0.01) indicating decreased compliance of the right ventricle. While the systolic and diastolic functions were normal, all the HRV parameters in the thalassemia group were significantly lower than the control group (P = 0.005).

CONCLUSIONS

Significant decrease in HRV and increase in PW late diastolic forward flow in pulmonary artery in the absence of systolic or diastolic dysfunction, points out that these parameters can be useful in detection of early cardiac impairment.

Signal-averaged electrocardiogram may be a beneficial prognostic procedure in the postoperative follow-up tetralogy of fallot patients to determine the risk of ventricular arrhythmias

Early detection of arrhythmias after congenital heart disease surgery is important because it can help decrease morbidity and mortality. Standard electrocardiograms (ECGs) contain frequencies between 0.05 and 100 Hz, but higher frequencies are also present. Using high-resolution technology, the highest amplitudes of these high-frequency components within the QRS complex can be recorded and analyzed. We studied the relationship between ventricular late potentials, ventricular arrhythmias and right ventricular systolic pressure in 22 patients who underwent tetralogy of Fallot repair (mean follow-up, 40.1 +/- 33.5 months). Holter ECG monitoring and signal-averaged electrocardiograms (SAECGs) were performed. SAECG parameters studied included the duration of the filtered QRS, the duration of terminal QRS below 40 muV, and the root mean square amplitude of the terminal 40 msec. Cardiac catheterization was performed on 19 patients. Eighteen healthy volunteers were studied as a control. Ventricular arrhythmias were found in 13 patients; right ventricular systolic hypertension was found in 1 patient. No significant residual ventricular septal defects were detected. Eight patients had ventricular late potentials. Right ventricular systolic pressure did not differ significantly between patients with or without late potentials. There were significant differences between patients with ventricular arrhythmias and healthy volunteers; filtered QRS duration was significantly longer in patients with ventricular arrhythmias. SAECG may be beneficial in determining ventricular arrhythmia risk in tetralogy of Fallot patients postoperatively.

Signal-averaged electrocardiography in normal newborn infants

Signal-averaged electrocardiograms (SAECGs) were recorded with bipolar orthogonal and standard 12-lead settings in 29 term healthy newborn infants. SAECGs performed with the two lead configurations were similar in quality and quantity. For the duration of the QRS complex (QRSD), the upper limit of normality for newborn infants can be set to 100 ms. It is similar in individual bipolar orthogonal and individual standard 12-lead recordings as well as in filtered QRSD in the vectorcardiograms (the vector magnitude, VM, and the sum of extremity leads). In individual leads of bipolar orthogonal and standard 12-lead recordings, root-mean-square voltage of the terminal 40 ms of the QRS complex (RMS40) is widely scattered and unsuitable as discriminant variable. For VM and the sum of the extremity leads, the same reference values for RMS40 and duration of low-amplitude signal can be used as applied in adults. Individual lead recordings provide complementary information in addition to vectorcardiograms. There are practical advantages using standard 12-lead compared to conventional bipolar orthogonal configurations. The widespread use of standard 12-lead ECG in routine medical practice makes its utility advantageous also in performing signal-averaged electrocardiography.

Evaluation of dysrhythmia in children with muscular dystrophy

Myocardial involvement and dysrhythmia are common findings with muscular dystrophy and are among the leading causes of death. The authors evaluated rhythm and conduction abnormalities in children with muscular dystrophy by electrocardiography, signal-averaged electrocardiography, and Holter monitoring. Twenty-nine patients (mean age, 8 years) and 29 healthy control subjects were included in the study. Sixty-two percent of patients had electrocardiographic abnormalities defined as deep Q waves in V6, tall R waves in V1, and QRS axis deviation. The cardiomyopathy index was significantly greater in the patient group whereas QT and QTc dispersion values showed no significant difference. Holter monitoring revealed premature atrial and ventricular contractions more frequently than normal. However all were classified as Lown I and II. Mean heart rate was significantly higher in the patient group. The electrocardiograms of 41% of the patients showed late potentials. No relationship with these changes and cardiac function was observed. During the study, one patient died whose cardiomyopathy index was longer and had late potentials detected with signal-averaged electrocardiography. In conclusion, standard electrocardiography, cardiomyopathy index, signal-averaged electrocardiography, and Holter monitoring are valuable and reliable monitoring methods in children with muscular dystrophy.

Signal-averaged electrocardiography in healthy children: influence of age, body size, and gender

Our objective was to determine influence of age, body size, and gender on SAECG signals and to establish normal range for standard SAECG parameters in the pediatric population. Five hundred thirty healthy children and adolescents (290 males, 240 females) aged 6.0-17.3 years were studied with high resolution ECG. Patients were divided into five age groups, and each age group was divided in two subgroups according to gender. Parameters studied were filtered QRS duration, root mean square (RMS) voltage of the last 40 ms and of the last 30 ms of the filtered QRS complex, and duration of the terminal waveform of the filtered QRS < 40 microV of amplitude (LAS). After validation of the distribution of the various variables, means, standard deviations, and 95% confidence intervals were determined for each SAECG parameter at 25- to 250-Hz filtering and at 40- to 250-Hz filtering for the ten subgroups. There was a significant age and body surface area (BSA)-associated increase in filtered QRS duration in boys and girls, and a decrease in RMS voltage of the end of the QRS complex in girls. In addition, girls had a significantly shorter QRS and longer LAS durations than boys. These differences of signal-averaged signals between genders were not related to age or body size differences since analysis of covariance with age at evaluation or BSA as covariates showed the same trend. Three children (0.6%) had a SAECG out of normal range for age for the four parameters studied either at 25- or 40-Hz high pass filter. Due to the large sample studied, our results provide a basis for interpretation of SAECG in children. Normal ranges for the various variables were determined, and it appeared that adjustments for age, body size, and gender are mandatory when studying SAECG in children.

Abnormal serum uric acid levels in children

Measurement of the serum uric acid level, most commonly considered in adult patients, is frequently obtained inadvertently for pediatric patients because it is a standard component of many multichannel chemistry profiles offered by clinical laboratories. Most standard references for normal uric acid values do not take into account the impact of the metabolic changes in children at different ages on the uric acid level. A substantial number of childhood conditions may produce perturbations in the serum uric acid level. Knowledge of normal serum uric acid levels and of the conditions affecting those levels in children enables a more focused pursuit of underlying abnormalities.

Normal values for the childhood signal-averaged ECG

To obtain normative data for the childhood signal-averaged ECG (SAECG), we obtained SAECGs in 155 volunteers, aged 5-15 years, using Frank leads and a Fourier transform filter. Unfiltered QRS duration (QRSDU) and filtered QRS duration (QRSDF) were significantly longer in males, and the root mean square of the terminal 40 ms (RMS40) was significantly higher in females. There were no gender differences in the duration of high frequency low amplitude signals < 40 microV (DHFLA). All SAECG variables were significantly related to body surface area (BSA). Regression models were established for SAECG variables. For males, the predicted mean + 1.96 standard deviations (SD) for QRSDF (97.5th centile) ranged from 114 ms at BSA 0.70 m2 to 123 ms at 1.90 m2. For females, the predicted mean + 1.96 SD for QRSDF ranged from 110 ms at BSA 0.70 m2 to 119 ms at 1.90 m2. For males and females, the predicted mean + 1.96 SD for DHFLA ranged from 34 ms at 0.70 m2 to 38 ms at 1.90 m2. For males, the predicted mean - 1.96 SD (2.5th centile) for RMS40 (based on natural logarithm model) ranged from 30 microV at 0.70 m2 to 15 microV at 1.90 m2. For females, the predicted mean -1.96 SD for RMS40 ranged from 42 microV at 0.70 m2 to 20 microV at 1.90 m2. In children 5-15 years of age, both gender and BSA need to be taken into account when interpreting the SAECG.