Cardiac involvement is a common and serious problem in multisystem inflammatory syndrome in children (MIS-C). Echocardiographic evaluation of systolic and diastolic function by traditional, tissue Doppler and three-dimensional (3D) echocardiography was performed in consecutive 50 MIS-C patients during hospitalization and age-matched 40 healthy controls. On the day of worst left ventricular (LV) systolic function (echo-1), all left and right ventricular systolic function parameters were significantly lower ( p < 0.001), E/A ratio was significantly lower, and averaged E/e′ ratio was significantly higher (median 1.5 vs. 1.8, p < 0.05; 8.9 vs. 6.3, p < 0.001 respectively) in patients compared to control. Patients were divided into 2 groups according to 3D LV ejection fraction (LVEF) on the echo-1: Group 1; LVEF < 55%, 26 patients, and group 2; LVEF ≥ 55%, 24 patients. E/e′ ratio was significantly higher in group 1 than group 2 and control at discharge (median 7.4 vs. 6.9, p = 0.005; 7.4 vs. 6.3, p < 0.001 respectively). Coronary ectasia was detected in 2 patients (z score: 2.53, 2.6 in the right coronary artery), and resolved at discharge. Compared with group 2, group 1 had significantly higher troponin-I (median 658 vs. 65 ng/L; p < 0.001), NT-pro BNP (median 14,233 vs. 1824 ng/L; p = 0.001), procalcitonin (median 10.9 vs. 2.1 µg/L; p = 0.009), ferritin (median 1234 vs. 308 µg/L; p = 0.003). The most common findings were ventricular systolic dysfunction recovering during hospitalization, and persisting LV diastolic dysfunction in the reduced LVEF group at discharge. Coronary artery involvement was rare in the acute phase of the disease. Also, in MIS-C patients, the correlation between LV systolic dysfunction and markers of inflammation and cardiac biomarkers should be considered. Supplementary Information The online version contains supplementary material available at 10.1007/s00246-021-02738-3.

Infantile malignant osteopetrosis (IMO; OMIM 259700) is a rare inherited bone disease characterized by reduced or dysregulated activity of osteoclasts, resulting in generalized osteosclerosis. The disease usually presents within the first few months of life with anemia, hepatosplenomegaly, frontal bossing, nystagmus, blindness, deafness, and bone fractures. Children with IMO are at risk of developing hypocalcemia, with attendant tetanic seizures. We report the case of a baby boy who presented with neonatal hypocalcemia. Skeletal radiographs demonstrated sclerotic bones and a dense base of the skull with typical "space alien" face confirming the diagnosis of IMO. Pancytopenia developed at 2 months of age. Visual evoked potential showed severe bilateral optic nerve damage. Genetic mutation study revealed a new mutation in exon 13 of the TCIRG1 gene. Neonatal hypocalcemia can occur as result of IMO, which is easily missed out by clinicians. This causes delay in establishing the diagnosis and starting necessary treatment. Therefore, osteopetrosis should be kept in mind as a rare cause of neonatal hypocalcemia.

Coronavirus disease of 2019 (COVID-19) is a cause of significant morbidity and mortality worldwide. Although COVID-19 clinical manifestations are mainly respiratory, major cardiac complications are being reported. The mechanism of cardiac injury and arrhythmias is unclear. Also, drugs currently used to treat the COVID-19 may prolong the QT interval and may have a proarrhythmic propensity. The study aims to investigate the effects of COVID-19 infection with asymptomatic and mild symptoms on trans-myocardial repolarization parameters in children without treatment. A total of 105 COVID-19 patients were compared with 40 healthy children. The patient and control group data were compared by calculating the QT interval, corrected QT (QTc), QT dispersion (QTd), QTc dispersion (QTcd), Tp-e, Tp-e dispersion, Tp-e/QT ratio, and Tp-e/QTc ratio on the 12-lead surface electrocardiogram. The mean age was determined as 11.2 ± 0.3 years in the patient group, and 10.8 ± 2.1 years in the control group. In the COVID-19 group, QTd, QTcd, Tp-e, Tp-e dispersion, Tp-e/QT ratio and Tp-e/ QTc ratio were statistically higher than the control group. The ventricular repolarization was impaired even in asymptomatic children with COVID-19 infection. These results suggest the need to further assess the long terms risks of prolonged QT dispersion in the setting of COVID-19 infection.

BACKGROUND Vitamin D is involved in cardiac contractility and myocardial calcium hemostasis, and vitamin D deficiencies are known to cause various cardiovascular disorders and have been linked with sudden cardiac death. AIMS The aim of the study was to evaluate repolarization distribution, represented by QT interval, corrected QT interval (QTc), QT dispersion, Tpeak -to -Tend (Tp -e) interval, Tp -e/QTc ratio, JT interval, JT dispersion, and Tp -e/JTpeak ratio in children with vitamin D deficiency. Moreover, we aimed to determine the relationship between ventricular repolarization anomalies and vitamin D deficiency. METHODS The study included 50 adolescent patients with vitamin D deficiency (vitamin D <20 ng/ml), 50 adolescent patients with vitamin D insufficiency, and 50 age -matched controls (vitamin D level >30 ng/ml). QTc duration, QT dispersion, JTpeak duration, JT dispersion, Tp -e, Tp -e/JTpeak ratio, and Tp -e/ QTc ratio were recorded on electrocardiogram. RESULTS Patients with vitamin D deficiency or insufficiency had longer Tp -e interval (P <0.001), while Tp -e/QTc and Tp -e/JTpeak ratios were found to be increased in the same group of patients (P = 0.005 and P <0.001, respectively). QT dispersion and JT dispersion were higher in the deficient group when compared with the other groups (P = 0.045 and P = 0.02, respectively). CONCLUSIONS The present study, conducted in a pediatric population, is the first in the current literature to assess the relationship between ventricular repolarization anomalies and vitamin D deficiency.

The prolongation in the PR interval on the electrocardiogram is one of the minor criteria of Jones. Abnormal increases in the PR interval lead to hemodynamic impairments caused by atrioventricular asynchrony and is called pseudo-pacemaker or pacemaker-like syndrome in the literature. A 13-yearold boy who had polyarthralgia for six weeks was referred to the emergency room because of syncope while exerting effort. In the electrocardiography, the P wave was regularly seen at the onset of the T wave immediately after the QRS wave with extremely prolonged PR interval and mild tachycardia. Also, 24 hours rhythm Holter recording showed atrioventricular dissociation. The echocardiography revealed findings of severe carditis. Diagnosis of acute rheumatic fever accompanying pacemaker-like syndrome was made. Although the recommendation for marked first-degree atrioventricular block that causes hemodynamic impairment is pacemaker implantation, a significant improvement in the PR prolongation was observed in the short term with anti-inflammatory treatment because the impairment of conduction in the patient was due to inflammation. The pacemaker-like syndrome in a child is being reported for the first time in the literature.