OBJECTIVE: Vitamin B12 is involved in the production of adrenaline from noradrenaline. It is the cofactor involved in catecholamine degradation and plays a role in myelin synthesis. The current study aimed to investigate the association between vitamin B12 levels and postural orthostatic tachycardia syndrome (POTS) during adolescence when accelerated myelin synthesis increases the vitamin B12 need. METHODS: One hundred twenty-five patients (mean age 11.1 ± 2.3 years; 60% female) reporting short-term loss of consciousness and diagnosed with vasovagal syncope based on anamnesis with a normal distribution and 50 control subjects (mean age 10.94 ± 2.5 years, 62% female) were included in this study. Serum vitamin B12, folic acid, and ferritin levels were measured prospectively in addition to other tests. We defined vitamin B12 deficiency as a serum level <300 pg/mL.1–4 RESULTS: Vitamin B12 levels were significantly lower in the patient group compared with the control group (47.2% vs 18%, P < .001). In the patient group, children with the POTS pattern had significantly lower vitamin B12 levels compared with children without the POTS response (P = .03). CONCLUSIONS: Vitamin B12 deficiency in patients with POTS may lead to sympathetic nervous system baroreceptor dysfunction.

Obesity is associated with a number of risk factors, such as hyperlipidemia, hyperinsulinemia, hypertension, and early atherosclerosis. Evidence indicates that atherosclerosis begins in childhood and progresses over decades. In this work, we examined the relationship between cardiovascular risk factors and ultrasonographic signs of subclinical atherosclerosis in 77 obese children and adolescents compared to 40 non-obese healthy peers. Carotis intima media thickness (cIMT), carotid artery compliance (CAC), brachial artery flow-mediated dilatation (FMD), and established cardiovascular risk factors were studied. In the obese patients, cIMT was significantly increased (0.57 mm vs 0.45 mm, p < 0.001) whereas CAC (1.84% vs 3.29%, p < 0.001) and FMD (9.67 % vs 14.81%, p < 0.001) were significantly decreased. In multiple linear regression analysis, a relation was observed between cIMT, CAC, brachial FMD on one hand, and body mass index (BMI) on the other. Among the lipid anomalies, only hypertriglyceridemia was found to be positively correlated with cIMT. Additionally, we found a significant association between waist circumference (WC) and FMD. These findings indicate that obesity in children is associated with arterial wall alterations and endothelial dysfunction. In hyperlipidemic situations, only hypertriglyceridemia was found to be positively correlated with cIMT. This finding has consistently indicated TG to be a risk factor for the development of atherosclerosis. To our knowledge this is the first study to determine the relation between FMD and WC, which is used as a parameter of obesity in childhood.

Neurocardiac syncope (NS) is a common cause of syncope in children. The mechanism, though related to abnormalities in autonomic function, has not been fully elucidated, particularly in pediatric patients. This study assessed the heart-rate variability (HRV) response to head-upright tilt-table test (HUT) in children with NS and normal volunteers. Spectral and time-domain analysis of HRV was used to assess changes in autonomic function in 27 children (9 male, mean age 12.3 +/- 1.6 years) with a history of at least one episode of syncope and positive passive HUT and 27 age-matched normal volunteers with negative passive HUT before and during postural tilt and to attempt to relate such changes to specific types of hemodynamic response to tilt. Frequency-domain measurements of the high-(HF) and low-(LF) frequency bands and the ratio LF/HF were derived from Holter recordings and computed by fast Fourier analysis for 5-min intervals. Time-domain measurements of the SDNN, SDNNI, SDANN, RMSSD, and triangular index were derived from 24-h Holter recordings. There were no significant differences between clinical characteristics, time-domain, and basal frequency domain parameters of the groups. Mean values of LF and LF/HF ratio was increased and HF was decreased significantly in response to tilt in both patient and control groups. Mean values of LF and LF/HF ratio were higher and HF was lower compared to controls immediately after tilt. LF and LF/HF ratio showed a statistically significant decrease and a significant increase in HF during syncope in patients. The three subgroups of patients had similar patterns of changes in autonomic activity. The results of this study show that although the basal autonomic function was similar to that of the control group, patients with NS have a different pattern of response to the HUT. In our study, patients with NS demonstrated an exaggerated response to the HUT. This exaggerated response may be the factor that activates the pathological reflexes of NS. The pathological mechanism leading to NS appears to be independent of the specific type of hemodynamic response to HUT.

This study investigated the predictors of chronic valvular disease in children with rheumatic carditis. The short- to mid-term follow-up records of 88 patients (mean age, 10.68 ± 2.5 years) with chronic rheumatic heart disease were reviewed. The mean follow-up period was 2.95 ± 1.4 years. Valvular involvement completely improved for 24 of the patients (27%) during the follow-up period. The multivariate logistic regression analysis found initial left ventricular dilation to be a significant independent risk factor associated with the persistence of either valvular involvement or mitral regurgitation. Furthermore, persistence of mitral regurgitation was found to be strongly correlated with cardiac murmur at admission. No significant correlation was detected between age, gender, severity of valvular involvements at initial evaluation, and chronic valvular disease. The majority of patients with rheumatic carditis had normal left ventricular systolic function. However, a significant proportion of patients had left ventricular dilation, reported in the medical literature to be associated with the severity of valve involvement. This study found no relation between initial severity of valve involvements and chronic valvular disease. For this reason, increased left ventricular end-diastolic diameter may be secondary to myocardial involvement independent of valvular regurgitation. The findings in this study also suggest that subclinic carditis had a better outcome than clinically evident carditis.

The children with repaired TOF had impaired ventricular and pulmonary functions. Hence, right ventricular MPI along with FEV1, FVC and 6MWT distance may be useful in the follow-up of children with repaired TOF.