Catheter ablation (CA) of supraventricular tachycardias (SVTs) is conventionally performed with the aid of X-ray fluoroscopy. Usage of a three-dimensional (3D) electro-anatomical mapping (EAM) system and intracardiac echocardiography (ICE) enables zero-fluoroscopy ablation, eliminating the harmful effects of radiation. We retrospectively analyzed the feasibility, effectiveness and safety of zero-fluoroscopy radiofrequency and cryoablation of various types of SVTs in pediatric patients. Overall, in 171 consecutive patients (12.5 ± 3.9 years), 175 SVTs were diagnosed and 201 procedures were performed. The procedural success rate was 98% (193/197), or more precisely, 100% (86/86) for AVNRT, 95.8% (91/95) for AVRT, 94.1% (16/17) for AT and 100% (2/2) for AFL. No complications were recorded. Follow-up was complete in 100% (171/171) of patients. During the mean follow-up period of 488.4 ± 409.5 days, 98.2% of patients were arrhythmia-free with long-term success rates of 98.7% (78/79), 97.5% (78/80), 100% (13/13) and 100% (2/2) for AVNRT, AVRT, AT and AFL, respectively. Zero-fluoroscopy CA of various types of SVTs in the pediatric population is a feasible, effective and safe treatment option.

Background/Objectives: The microtubule-associated scaffold protein 1 (MTUS1) gene affects the microtubule stability and cell polarity in the heart and could thus lead to the development of left ventricular noncompaction (LVNC). Pathological gene variants in MTUS1 are associated with pathological phenotypes in both cell cultures and animal models. However, the literature lacks human studies on the specific effects of the MTUS1 gene in heart disease, particularly in congenital LVNC. Methods: We present a case of a male infant, diagnosed with LVNC, who passed away at the age of 8 months due to end-stage heart failure. In the investigation process of the etiology of LVNC, whole-genome sequencing using next-generation sequencing was performed in the patient and his first-degree family members. Results: Genetic analysis identified two heterozygous variants in the MTUS1 gene (NM_001363059.2:c.87C>G and NM_001363059.2:c.2449+421_2288-425del) in the presented patient. The first variant introduced an early stop codon, while the second caused the deletion of an entire exon, both of which significantly altered the protein structure. The older brother of the patient, at the age of 5 years, was a carrier of both variants; however, he was asymptomatic and without signs of heart disease on cardiac ultrasonography. Conclusions: Although, in theory, defects in the MTUS1 gene may contribute to the development of LVNC, our observations indicate that MTUS1 variants alone are not sufficient to cause LVNC or lead to any significant developmental disorder. Additional factors, whether genetic or environmental, are likely necessary for the clinical manifestation of LVNC.

Partial anomalous pulmonary venous return (PAPVR) with dual drainage is a very rare congenital heart anomaly. We report the case of a 6-year-old boy with PAPVR in whom both upper pulmonary veins (PVs) drain anomalously into the systemic venous circulation, while maintaining preserved intrapulmonary collateral venous connections with the remaining pulmonary veins draining into the left atrium. Careful balloon occlusion testing of the anomalous PVs was performed, simultaneously with measurements of pulmonary pressures and control angiography, proving the absence of venous congestion in the upper lung fields during the pulmonary venous phase. Transcatheter occlusion using vascular plugs was safely and successfully performed.

Partial anomalous pulmonary venous return (PAPVR) with dual drainage is a very rare congenital heart anomaly. We report the case of a 6-year-old boy with PAPVR in whom the both upper pulmonary veins (PVs) drain anomalously into the systemic venous circulation, while having preserved intrapulmonary collateral venous connection with remaining pulmonary veins draining into the left atrium. Careful balloon occlusion testing of the anomalous PVs was performed, simultaneously with measurements of pulmonary pressures and control angiography proving the absence of venous congestion in the upper lung fields during the pulmonary venous phase. Transcatheter occlusion using vascular plugs was safely and successfully performed.