Pediatric hypertrophic cardiomyopathy caused by a novel TNNI3 variant.

TNNI3 is a gene that causes hypertrophic cardiomyopathy (HCM). A 14-year-old girl who was diagnosed with nonobstructive HCM presented with cardiopulmonary arrest due to ventricular fibrillation. Genetic testing revealed a novel de novo heterozygous missense variant in TNNI3, NM_000363.5:c.583A>T (p.Ile195Phe), which was determined to be the pathogenic variant. The patient exhibited progressive myocardial fibrosis, left ventricular remodeling, and life-threatening arrhythmias. Genetic testing within families is useful for risk stratification in pediatric HCM patients.

Second Micra leadless pacemaker implantation by using intracardiac echocardiography.

The strategy after battery depletion was not established in Micra leadless pacemaker system (Micra). There are still some concerns in the 2nd Micra implantation, such as the mechanical interaction between both devices. The position of the 2nd Micra should be placed apart from the 1st Micra. We present a case of 1st Micra battery depletion who successfully underwent the 2nd Micra implantation under the intracardiac echo guidance. In our case, intracardiac echo was a very effective tool for confirming the location of Micra implantation.