ENDOMYOCARDIAL BIOPSY FROM THE RIGHT CARDIAC CHAMBERS IN PERDIATRIC PATIENT WITH CARDIAC ARRHYTHMIAS

To assess the results of endomyocardial biopsy (EMB) in pediatric patients with different cardiac arrhythmias, 19 patients were examined. When selecting appropriate candidates for EMB., guidelines and indications to EMB by AHA/ACC/ESC were followed. Cardiac arrhythmias were ventricular ones in 14 cases, 3 patients had atrial tachycardia, in one patient, the sick sinus syndrome was documented (tachy-brady syndrome: sinus bradycardia with paroxysmal atrial fibrillation), and in one more patient, paroxysmal atrial fibrillation. Indications to EMB were long-term persistent progressing cardiac arrhythmia, cardiac dilatation with or without a decreased ejection fraction, and resistance to antiarrhythmic therapy. In 16 cases (84.2%), EMB was carried out during the radiofrequency ablation (RFA) of ectopic foci and, in 2 cases (10.5%), during the cardioverter-defibrillator (ICD) implantation. In 1 case (5.3%), EMB was an independent procedure in the patient with the sick sinus syndrome, tachy-brady type. EMB was performed using a bioptome manufactured by Cordis, 5-8 tissue samples were collected from the right ventricle apex and inter-ventricular septum. The light and polarization microscopy of biopsy samples was performed; the standard protocol of endomyocardial biopsy was followed. Eighty-six tissue samples were collected in 19 patients. No adverse events during any case of the EMB procedure were documented. According to the EMB data, the diagnosis of myocarditis was confirmed in 9 pediatric patients; in 5 cases, it was active myocarditis, in 2 subjects, borderline myocarditis; chronic and recovered myocarditis was found in 1 pediatric patient apiece. In 2 patients of the study group, signs of myocarditis were associated with those of arrhythmogenic cardiomyopathy/right ventricular dysplasia (AC/RVD). The viral genome was confirmed in cardiomyocytes in 4 children: parvovirus B19 in 2 patients, enterovirus and Epstein-Barr virus, in 1 patient apiece. In 3 patients (15.8%), morphological alterations were considered signs of primary cardiomyopathy. In 6 patients (31.5%), no pathological changes were found in the biopsy samples. In one case (5.3%), no morphological assessment was made due to technical issues. Thus, according to the data of EMB performed in the authors’ hospital in children with progressing cardiac arrhythmias, myocarditis was revealed in 47.4% of cases. It cannot be ignored indeed that such a high ratio of patients with the confirmed substrate of arrhythmia is caused by the thorough selection of candidates for the procedure and the initially high probability of myocarditis, predominantly its latent type, as a cause of malignant cardiac arrhythmia.

endomyocardial biopsy, myocarditis, arrhythmogenic cardiomyopathy/right ventricular dysplasia, dilated cardiomyopathy, magnetic resonance imaging, immunohistochemistry assessment

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