A MYH7 variant in a five-generation-family with hypertrophic cardiomyopathy.

Background: Hypertrophic cardiomyopathy (HCM) is a genetic condition with a prevalence of 1:500-1:3 000. Variants in genes encoding sarcomeric proteins are mainly responsible for the disease. MYH7 gene encoding a myosin heavy chain beta, together with MYPBC3 gene are the two most commonly affected genes. The clinical presentation of this disease varies widely between individuals. This study aims to report a variant of MYH7 responsible for HCM in a five-generation family with a history of cardiac problems. Methods: The diagnosis was established according to the European Society of Cardiology HCM criteria based on two-dimensional Doppler echocardiography or cardiovascular magnetic resonance. Genetic analysis was performed using next-generation-sequencing and Sanger method. Results: The medical history of the presented family began with a prenatal diagnosis of HCM in the first child of a family with previously healthy parents. Five generations of the family had a long history of sudden cardiac death and cardiac problems. A NM_000257.4:c.2342T>A (p.Leu781Gln) variant was detected in the MYH7 gene. It was heterozygous in the proband and in all affected individuals in a large family. The variant was present in 10 affected members of the family, and was absent in 7 members. The clinical course of the disease was severe in several members of the family: three family members died of sudden cardiac death, one patient required heart transplantation, three underwent septal myectomy, and three required implantable cardioverter defibrillator (ICD) implantation. Conclusion: Herein, we report a MYH7 variant responsible for HCM. Familial HCM is inherited primarily in autosomal dominant mode, which is in accordance with our study. However, the presented family showed a broad clinical spectrum of HCM. Out of 10 family members with positive genetic testing 8 had severe presentation of the disease and 2 had a mild phenotype. This suggests that the severity of the disease may depend on other factors, most likely genetic.

Eradication of cervical canal colonization associated with prophylactic cervical cerclage: the look further study.

OBJECTIVES: The perioperative management of the cervical cerclage procedure is not unified. In general population controlling microbiome cervical status does not affect obstetric outcomes, but it might be beneficial in patients with cervical insufficiency. The aim of our study was to present the obstetric, neonatal and pediatric outcomes of patients undergoing the cervical cerclage placement procedure in our obstetric department using a regimen of care that includes control of the microbiological status of the cervix and elimination of the pathogens detected. MATERIAL AND METHODS: Thirty-five patients undergoing cervical cerclage in the 2nd Department of Obstetrics and Gynecology, Medical University of Warsaw, were included in the study. The procedure was performed only after receiving a negative culture from the cervical canal. RESULTS: Thirty-one (88.6%) patients delivered after the 34th and twenty-eight (80.0%) after the 37th week of gestation. The colonization of the genital tract was present in 31% of patients prior to the procedure, in 42% of patients - during the subsequent pregnancy course and in 48% of patients - before delivery. A total of 85% of patients who had miscarriage or delivered prematurely had abnormal cervical cultures. In patients with normal cervical cultures, and 91.7% of women delivered at term. No abnormalities in children's development were found. CONCLUSIONS: Controlling microbiological status of the cervical canal results in better or similar outcomes to those reported by other authors in terms of obstetric and neonatal outcomes. Active eradication of the reproductive tract colonization potentially increases the effectiveness of the cervical cerclage placement.

Biomarkers of the Complement System Activation (C3a, C5a, sC5b-9) in Serum of Patients before and after Liver Transplantation.

The liver has a huge impact on the functioning of our body and the preservation of homeostasis. It is exposed to many serious diseases, which may lead to the chronic failure of this organ, which is becoming a global health problem today. Currently, the final form of treatment in patients with end-stage (acute and chronic) organ failure is transplantation. The proper function of transplanted organs depends on many cellular processes and immune and individual factors. An enormous role in the process of acceptance or rejection of a transplanted organ is attributed to, among others, the activation of the complement system. The aim of this study was the evaluation of the concentration of selected biomarkers' complement system activation (C3a, C5a, and sC5b-9 (terminal complement complex)) in the serum of patients before and after liver transplantation (24 h, two weeks). The study was conducted on a group of 100 patients undergoing liver transplantation. There were no complications during surgery and no transplant rejection in any of the patients. All patients were discharged home 2-3 weeks after the surgery. The levels of all analyzed components of the complement system were measured using the ELISA method. Additionally, the correlations of the basic laboratory parameters-C-reactive protein (CRP), hemoglobin (Hb), total bilirubin, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGTP), and albumin-with the parameters of the complement system (C3a, C5a, and sC5b-9) were determined. In our study, changes in the concentrations of all examined complement system components before and after liver transplantation were observed, with the lowest values before liver transplantation and the highest concentration two weeks after. The direct increase in components of the complement system (C3a, C5a, and sC5b-9) 24 h after transplantation likely affects liver damage after ischemia-reperfusion injury (IRI), while their increase two weeks after transplantation may contribute to transplant tolerance. Increasingly, attention is being paid to the role of C3a and CRP as biomarkers of damage and failure of various organs. From the point of view of liver transplantation, the most interesting correlation in our own research was found exactly between CRP and C3a, 24 h after the transplantation. This study shows that changes in complement activation biomarkers and the correlation with CRP in blood could be a prognostic signature of liver allograft survival or rejection.

Diastolic function evaluation in children with ventricular arrhythmia.

Premature ventricular contractions (PVC) are frequently seen in children. We evaluated left ventricular diastolic function in PVC children with normal left ventricular systolic function to detect whether diastolic function disturbances affect physical performance. The study group consisted of 36 PVC children, and the control group comprised 33 healthy volunteers. Echocardiographic diastolic function parameters such as left atrial volume index (LAVI), left atrial strains (AC-R, AC-CT, AC-CD), E wave, E deceleration time (Edt), E/E' ratio, and isovolumic relaxation time (IVRT) were measured. In the cardiopulmonary exercise test (CPET), oxygen uptake (VO2 max) was registered. Evaluation of diastolic function parameters revealed statically significant differences between the patients and controls regarding Edt (176.58 ± 54.8 ms vs. 136.94 ± 27.8 ms, p < 0.01), E/E' (12.6 ± 3.0 vs. 6.7 ± 1.0, p < 0.01), and IVRT (96.6 ± 19.09 ms. vs. 72.86 ± 13.67 ms, p < 0.01). Left atrial function was impaired in the study group compared to controls: LAVI (25.3 ± 8.2 ml/m2 vs. 19.2 ± 7.5 ml/m2, p < 0.01), AC-CT (34.8 ± 8.6% vs. 44.8 ± 11.8%, p < 0.01), and AC-R-(6.0 ± 4.9% vs. -11.5 ± 3.5%, p < 0.01), respectively. VO2 max in the study group reached 33.1 ± 6.2 ml/min/kg. A statistically significant, moderate, negative correlation between VO2 max and E/E' (r = -0.33, p = 0.02) was found. Left ventricular diastolic function is impaired and deteriorates with the arrhythmia burden increase in PVC children. Ventricular arrhythmia in young individuals may be related to the filling pressure elevation and drive to exercise capacity deterioration.

Cardiopulmonary capacity is reduced in children with ventricular arrhythmia.

BACKGROUND: Premature ventricular contractions (PVCs) are frequently seen in children and are considered benign. A substantial group of adolescents with PVCs complain about a broad range of clinical symptoms, including low exertion tolerance. OBJECTIVE: The purpose of this study was to evaluate prospectively whether ventricular arrhythmia affects physical performance in adolescents with normal left ventricular function, using a cardiopulmonary exercise test (CPET) and evaluating the electrocardiographic (ECG) characteristics of patients with PVCs with regard to exercise capacity. METHODS: The study group consisted of 49 children with PVCs and normal left ventricular function. The control group consisted of 36 healthy volunteers. Standard ECG, 24-hour Holter ECG, and CPET were performed. PVCs were analyzed for QRS duration, bundle branch block pattern, QRS axis, and coupling interval (CInt). For CPET, heart rate (HR), oxygen uptake (VO2max), predicted VO2max, and VO2max expressed as a percentage of the predicted value (%VO2) were measured. RESULTS: In 37 patients (76%), arrhythmia subsided during exercise. Patients achieved lower VO2max (32.9 ± 6.3 mL/min/kg) than controls (40.4 ± 6.7 mL/min/kg; P <.01). %VO2 was 71.0 ± 13.7 in patients and 79.3 ± 12.2 in controls (P <.01). Exercise HR at which PVCs subsided correlated with VO2max (r = 0.3; P = .07). Patients with persisting arrhythmia performed worse than those in whom arrhythmia subsided during exercise (VO2max, P <.01; %VO2,P <.01). No correlation between QRS and CInt parameters and VO2max was observed. CONCLUSION: Patients with PVCs have lower aerobic capacity than their healthy peers. Further worsening of exercise capacity is present when PVCs are preserved during effort.

Circadian Blood Pressure Profile in Pediatric Patients with Primary Hypertension.

Our study aimed to evaluate factors affecting circadian BP profile and its association with hypertension-mediated organ damage (HMOD) in pediatric patients with primary hypertension (PH). The study included 112 children (14.7 ± 2.1 age, 79 boys, 33 girls) with untreated PH. Non-dipping was defined as a nocturnal drop in systolic or diastolic BP (SBP, DBP) < 10%, and a nocturnal drop >20% was defined as extreme dipping. The nocturnal SBP drop was 10.9 ± 5.9 (%), and the DBP drop was 16.2 ± 8.5 (%). Non-dipping was found in 50 (44.6%) children and extreme dipping in 29 (25.9%) patients. The nocturnal SBP decrease correlated with BMI Z-score (r = −0.242, p = 0.010) and left ventricular mass index (LVMI) (r = −0.395, p = 0.006); diastolic DBP decrease correlated with augmentation index (AIx75HR) (r = 0.367, p = 0.003). Patients with a disturbed blood pressure profile had the highest LVMI (p = 0.049), while extreme dippers had the highest augmentation index (AIx75HR) (p = 0.027). Elevated systolic and diastolic BP dipping were risk factors for positive AIx75HR (OR 1.122 95CI (1.009−1.249) and OR 1.095 95CI (1.017−1.177). We concluded that disturbed circadian BP profile was common in children with PH and should not be considered a marker of secondary hypertension. A disturbed circadian BP profile may be associated with higher body weight. In pediatric patients with PH, non-dipping is associated with increased left ventricular mass, and extreme dipping may be a risk factor for increased arterial stiffness.

Electrocardiograms in school-aged healthy Polish children - an observational study.

BACKGROUND: Electrocardiographic (ECG) examination has long been used to assess cardiovascular function in clinical practice. Age-related ECG changes are observed as the cardiovascular system matures from the neonatal period to adolescence. AIM: This study aimed to evaluate effects of sex and age on ECG parameters in healthy schoolchildren. METHODS: The study included 336 healthy participants aged 5-12 years from the Masovian voivodeship. Children were divided into age groups of 5-8 and 9-12 years. Values for heart rate (HR), time intervals and amplitudes of P and QRS waves, and QRS axis for pediatric ECGs were estimated. RESULTS: Significant differences between boys and girls aged 5-8 years old were discovered for such parameters as PR interval, R-wave, S-wave, and the R/S ratio. Age-related decline in HR, Q-wave in V5 and V6, R-wave in V1-V4, and increase in QRS duration were noted. Girls presented a higher HR and shorter QRS than boys. HR, QRS axis, P wave amplitude in lead II, and amplitude of R and S in the precordial leads were different in our population than those previously reported. CONCLUSIONS: Pediatric ECG tracings were estimated for the first time for healthy Polish schoolchildren. Sex-related differences in selected ECG parameters in the younger age group were noticed. Several parameters differed from those previously reported in other ethnic populations. These findings are clinically significant and suggest that diagnostic criteria for pediatric ECG should be revised to establish if they are justifiable for the entire population.

A Scoping Review of Galectin-3 as a Biomarker of Cardiovascular Diseases in Pediatric Populations.

Galectin-3 as a cardiac biomarker has proven to be a significant prognostic tool in adults. However, it has not yet been established in the pediatric population as a biomarker in daily clinical practice. The aim of the study was to summarize the current knowledge on galectin-3 as a biomarker in children with cardiac conditions by reviewing the literature. Bibliographic databases such as PubMed, Web of Science and Embase were searched, and consequently twelve articles met the inclusion criteria. Supplemental handsearching of references delivered one additional source. These prospective studies concerning galectin-3 as a cardiac biomarker present analyses performed in cohorts composed of healthy children and children with cardiovascular diseases. The results, despite being based on small cohort studies, inform that galectin-3 could serve as a potential biomarker in cardiovascular risk stratification in children with heart failure, arrhythmia, Kawasaki disease or in patients undergoing cardiac surgery. The evidence for the usefulness of galectin-3 in the assessment of such pathologies as idiopathic dilated cardiomyopathy, coarctation of the aorta, functionally univentricular heart or tetralogy of Fallot were not completely confirmed. Galectin-3 seems to be a promising biomarker; however, there is a need for further research to establish its use in daily clinical practice.

Success rate and safety of catheter ablation in preexcitation syndrome: A comparison between adult and pediatric patients.

BACKGROUND: In contrast to adults, in whom cardiac rhythm disorders are mainly conditioned by coronary artery disease, in children, arrhythmias are most often associated with inherited heart disorders. Catheter ablation (CA) has an important role in the management of cardiac arrhythmias, in adults and children. The aim of the study was to assess and compare the efficacy and safety of CA in children and adults with preexcitation syndrome. METHODS: The study population comprised 43 adults and 43 children diagnosed with a Wolff-Parkinson-White syndrome (WPW). The mean age of the study population was 41 ± 15 years for adults and 14 ± 2.5 years for children. In all patients, an electrophysiological study and CA were performed. Analysis with respect to the procedure duration, fluoroscopy exposure time, location of accessory pathways (AP), immediate success rate and complications were performed. RESULTS: Electrophysiological study revealed the most frequent presence of left-sided AP (56% in children and 70% in adults). The mean procedure duration was 96 ± 36 min and 106 ± 51 min in children and adults, respectively (p = NS). The mean fluoroscopy duration was 8.5 ± 4.3 min and 5.9 ± 5.8 min in children and adults, respectively p < 0.05. The CA procedure was successful in 40 out of 43 (93%) adults and in 36 out of 43 (83.7%) children (p = NS). In 2 (4%) children minor complications occurred. CONCLUSIONS: Ablation in children and adults are equally effective with respect to short-term clinical observation.

Assessment of the physical performance in children with asymptomatic pre-excitation.

AIMS: Pre-excitation syndrome can lead to recurrent supraventricular tachycardias (SVTs) and carries a risk of sudden cardiac death (SCD). However, an underestimated consequence of antegrade conduction through an accessory pathway is fusion of intrinsic and accessory conduction that causes asynchronous activation and myocardial contraction that could be a cause for cardiac dysfunction and dilation. It is not known to what extent pre-excitation affects myocardial and physical performance in those patients. The aim of the study was to assess to what degree ventricular pre-excitation affects physical performance in children, using cardio-pulmonary exercise testing (CPET). METHODS AND RESULTS: The study group consisted of 30 asymptomatic children, aged 8-17 years, with pre-excitation and no history or documentation of SVT compared to 31 healthy controls matched according to sex and age. All patients underwent routine cardiology assessment and then CPET. Echocardiography showed there were no differences in the left ventricular size and function between the study and control group. During the CPET both, patients and controls achieved maximal effort. Patients in the study group showed significantly lower values of VO2max and anaerobic threshold when compared to controls. The most affected subgroup was patients with persistent pre-excitation throughout the exercise. CONCLUSIONS: Physical performance is affected in children with pre-excitation. This effect is stronger in patients with persistent delta wave observed throughout the exercise.

NT-proBNP as a Potential Marker of Cardiovascular Damage in Children with Chronic Kidney Disease.

Assessing cardiovascular disease (CVD) in children with chronic kidney disease (CKD) is difficult. Great expectations have been associated with biomarkers, including the N-terminal pro-brain natriuretic peptide (NT-proBNP). This study aimed to determine the correlation between NT-proBNP and cardiovascular complications in children with CKD. Serum NT-proBNP, arterial stiffness, common carotid artery intima-media thickness (cIMT), echocardiographic (ECHO) parameters (including tissue Doppler imaging), and biochemical and clinical data were analyzed in 38 pediatric patients with CKD (21 boys, 12.2 ± 4.2 years). Mean NT-proBNP in CKD patients was 1068.1 ± 4630 pg/mL. NT-proBNP above the norm (125 pg/mL) was found in 16 (42.1%) subjects. NT-proBNP correlated with glomerular filtration rate (GFR) (r = -0.423, p = 0.008), and was significantly higher in CKD G5 (glomerular filtration rate grade) patients compared to CKD G2, G3, and G4 children (p = 0.010, p = 0.004, and p = 0.018, respectively). Moreover, NT-proBNP correlated positively with augmentation index (AP/PP: r = 0.451, p = 0.018, P2/P: r = 0.460, p = 0.016), cIMT (r = 0.504, p = 0.020), and E/E' in ECHO (r = 0.400, p = 0.032). In multivariate analysis, logNT-proBNP was the only significant predictor of cIMT Z-score (beta = 0.402, 95CI (0.082-0.721), p = 0.014) and P2/P1 (beta = 0.130, 95CI (0.082-0.721), p = 0.014). Conclusions: NT-proBNP may serve as a possible marker of thickening of the carotid artery wall in pediatric patients with CKD. The final role of NT-proBNP as a biomarker of arterial damage, left ventricular hypertrophy, or cardiac diastolic dysfunction in CKD children needs confirmation in prospective studies.

Intracardiac atrial overdrive pacing as an alternative to extracorporeal membrane oxygenation in the treatment of cardiogenic shock due to drug refractory and incessant persistent junctional reciprocating tachycardia in a 7-month-old infant.

In the case of prolonged, undiagnosed persistent junctional reciprocating tachycardia in infants, compensatory mechanisms are exhausted leading to heart failure. However, when cardioverted to sinus rhythm patients often deteriorate due to cardiac output dependency on the higher rates. Extracorporeal membrane oxygenation (ECMO) is often used to stabilize their hemodynamic status. A 7-month-old female infant was admitted in cardiogenic shock due to drug refractory supraventricular tachycardia (SVT). Pharmacological cardioversion to sinus rhythm with heart rate (HR) of 90 bpm was achieved but resulted in hemodynamic deterioration and early recurrence of arrhythmia. Right atrial overdrive pacing (ODP) wire was introduced through femoral vein and allowed to override the tachycardia with 2:1 A:V block and HR of 160 bpm. ODP was continued for 24 h allowing to wean off the inotropic support. We postulate that ODP can be a safe and less invasive alternative to ECMO in stabilizing infants with cardiogenic shock due to intractable SVTs.

Evaluation of Galectin-3 Plasma Concentration in Adolescents with Ventricular Arrhythmia.

Galectin-3 (G3) is a biomarker known as an inflammatory state exponent. The aim of this paper was to analyze the G3 in adolescents with ventricular arrhythmia (VES) in order to evaluate its impact on myocardial tissue preservation. The study group (SG) consisted of 25 VES adolescents. The control group (CG) was 21 healthy children. G3 was assessed in the SG and CG. In the SG electrocardiography, Holter monitoring, echocardiography and CMR were performed. The G3 in SG was 13.45 ± 11.4 ng/mL and in CG 7.2 ± 2.0 ng/mL, p < 0.001. Moderate positive correlation between the G3 and z-score of the left ventricular diameter (r = 0.47, p = 0.041) and moderate negative correlation between the G3 and the left ventricular ejection fraction in cardiac magnetic resonance (CMR EF) (-0.49, p = 0.032) were found. According to the multiple linear regression analysis, CMR EF and VES were independent predictors for G3 elevation. Conclusion: Galectin-3 plasma concentration is elevated and correlates with the chosen left ventricular dysfunction parameters in adolescents suffering from ventricular arrhythmia. Further investigation is necessary to establish if elevated G3 is a useful biomarker for screening young individuals with ventricular arrhythmia who are at risk of structural cardiovascular pathology.

Adrenocorticotropin/cortisol ratio - a marker of psoriasis severity.

INTRODUCTION: The hypothalamic-pituitary-adrenal (HPA) axis plays a crucial role in systemic homeostasis and hormonal regulation of metabolic and immune functions. A similar HPA axis analog exists in the skin, where it regulates inflammation, cell proliferation and differentiation. Data regarding central HPA axis dysregulation in psoriasis are interesting but so far inconclusive. AIM: In the study we attempted to determine whether central HPA axis serum components correlate with psoriasis severity. MATERIAL AND METHODS: Forty-two patients (10 women and 32 men) hospitalized at the Department of Dermatology participated in the study. None of our patients received any systemic treatment. Venous blood samples were collected at 6.00 AM. The relationship between quantitative variables and psoriasis severity based on the Psoriasis Area and Severity Index (PASI) was assessed with proc logistic in SAS 9.4. RESULTS: The effect of adrenocorticotropin/cortisol ratio on the PASI group was OR 3.621 (95% confidence limits 1.217-10.775) for a 0.1 change in ratio (p = 0.02), meaning ACTH/cortisol ratio positively correlates with psoriasis severity. The effect of ACTH and cortisol on the PASI group was not statistically significant, with p-values of 0.30 and 0.23 respectively. Other inflammatory markers such as high-sensitivity C-reactive protein, neutrophils level, LDL, and total cholesterol did not show a significant correlation with PASI score. CONCLUSIONS: Our results support the role of HPA axis dysfunction in the complex pathogenesis of psoriasis, showing a positive correlation between morning ACTH/cortisol ratio and disease severity. ACTH/cortisol ratio can be regarded as a new biochemical marker of psoriasis severity worth further studies.

Management of Young Athletes with Asymptomatic Preexcitation-A Review of the Literature.

INTRODUCTION: The management of young athletes with asymptomatic preexcitation remains a challenge, regardless of the progress we have made in understanding the basis of condition and developing catheter ablation procedures. The risk of sudden death, however small, yet definite, being the first symptom is determining our approach. The aim of the study was to establish the current state of knowledge regarding the management of young athletes diagnosed with asymptomatic preexcitation, by conducting a literature review. MATERIAL AND METHODS: A comprehensive literature review was completed in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search was limited to English language publications using the following search terms: "asymptomatic" or "incidental" and "pre-excitation" or "Wolff-Parkinson-White" or "delta wave" and "athlete" or "sport". The search was supplemented by hand review of the bibliographies of previous relevant systematic reviews. RESULTS: The search resulted in 85 of abstracts, and the manual search of the bibliographies resulted in 24 additional papers. After careful analysis 10 publications were included in the review. In all but one of the presented papers, the authors used non-invasive methods and then either trans-esophageal or invasive EPS as a way to risk stratify asymptomatic patients. Evidence of rapid conduction through the accessory pathway was considered high risk and prompted sport disqualification. In the analysed reports there were combined: 142 episodes of the life-threatening events (LTE)/sudden death (SCD), of which 56 were reported to occur at rest, 61 during activity and no data were available for 25. CONCLUSIONS: athletic activity may impose an increased risk of life-threatening arrhythmias in patients with asymptomatic preexcitation; hence, a separate approach could be considered, especially in patients willing to engage in high-intensity, endurance and competitive sports.

Serum Klotho is correlated to cardiovascular complications of chronic kidney disease in children.

AIM: Aim of the study was to investigate soluble Klotho (sKl), fibroblast growth factor 23 (FGF23) concentrations, and their correlations with cardiovascular complications in children with CKD. MATERIALS AND METHODS: 38 children with CKD stages 2 - 5 were compared to 38 healthy controls in terms of: plasma FGF23, serum sKl, peripheral and central blood pressure, arterial stiffness (pulse wave velocity - (PWV)), carotid intima media thickness (cIMT), left ventricular mass index (LVMI), and diastolic function. Correlations between FGF23, sKl, and cardiovascular parameters were investigated. RESULTS: The CKD group was characterized by higher FGF23, lower sKl concentrations, higher peripheral and central blood pressure, arterial stiffness, cIMT, left ventricular mass index, and decreased E/A ratio compared to the control group. In CKD children, sKl correlated negatively with diastolic blood pressure (DBP), mean arterial pressure (MAP), central systolic, diastolic, and mean blood pressure, PWV, and LVMI. In multivariate analysis, higher sKl was a significant predictor of lower peripheral and central DBP and lower LVMI and E/A, whereas higher FGF23 was a predictor of higher of LVMI. CONCLUSION: (1) In children with CKD, decreased sKl might be a marker of elevated central blood pressure. (2) Both sKl decrease and FGF23 increase could possibly contribute to left ventricular hypertrophy in this group of patients.

Initial experience of catheter ablation for cardiac arrhythmias in children and adolescents at a newly built ablation centre.

BACKGROUND: Catheter ablation (CA) therapy is the first-choice treatment in adults with heart rhythm disturbances. Arrhythmias in adults are mainly conditioned by coronary artery disease. Aetiology of arrhythmias in children is mostly associated with inherited heart disorders. According to the current guidelines, CA is widely used in children, indicating the need to make it more achievable in the paediatric population. AIM: To assess the efficacy and safety of CA in children with different types of arrhythmias on the initial learning curve at a newly built Ablation Centre in the Independent Paediatric Hospital of the Medical University of Warsaw, Poland. METHODS: The study population comprised 32 children with supraventricular tachycardias, asymptomatic pre-excitation syndrome, or ventricular ectopic beats undergoing CA. The mean age of the study population was 14.1 ± 2.4 years. In all patients, electrophysiological study (EPS) and CA were performed. Analysis with respect to procedure duration, fluoroscopy exposure duration, location of accessory pathways (AP), success rate, recurrences, and complications was performed. RESULTS: The mean procedure duration was 105.4 ± 41.4 min (range 40-175 min). The mean fluoroscopy duration was 8:34 ± 5:01 min (range 1:28-21:01). The mean exposure to ionising radiation was 4.7 ± 3.2 mcG/kg. EPS revealed significantly more frequent presence of AP in the left side (57.1%). The radiofrequency ablation procedure was successful in 26 of 32 (81.3%) children, and cryoablation was successful in two of four patients. In two (6.3%) children minor complications occurred. CONCLUSIONS: Catheter ablation may be effectively performed without major complications in the initial phase of the learning curve if a reasonable approach with a gradual increase of the procedural complexity is taken.