Cor Vasa 2025, 67(1):67-72 | DOI: 10.33678/cor.2024.108

(Rare rhythm disorder in patients with hypertrophic obstructive cardiomyopathy during endocardial radiofrequency ablation of septal hypertrophy)

Katarína Doležalová, Zdeněk Stárek, Tomáš Honek, Filip Souček, Martin Pešl, Jan Krejčí

I. interní kardioangiologická klinika, Lékařská fakulta Masarykovy univerzity a Fakultní nemocnice u sv. Anny v Brně, Brno, Česká republika

Hypertrophic obstructive cardiomyopathy (HOCMP) is characterized by abnormal thickening or enlargement of the left ventricular myocardium mass of non-dilated left ventricle not explained solely by loading conditions and presence of obstruction in outflow tract of left ventricle. Surgical septal myectomy was the first choice method of invasive treatment of septal hypertrophy in the past which was replaced by alcohol septal ablation in the nineties of the 20th century and nowadays it is still worldwide used, safe, and effective method in reduction of septal hypertrophy. Nowadays there is a new method of non-pharmacological treatment of septal hypertrophy which is endocardial radiofrequency ablation of septal hypertrophy (ERASH). Main goal of our case report is to describe first experiences with ERASH method in our department. A forty- -three-year-old patient with diagnosed HOCMP and severe left ventricle outflow tract gradient (LVOTG) despite maximal pharmacological treatment who underwent alcohol septal ablation (ASA) in 2019, only with transient effect on LVOTG, and the new onset of right bundle branch block (RBBB). In 2021, there was still high LVOTG present on echocardiography - 127 mmHg and progressive symptomatology. The patient agreed to undergo ERASH. Hypertrophic part of septum and conduction system have been mapped and marked to avoid destruction. Radiofrequency ablation was started in the middle part of septal hypertrophy in safe distance from conduction system, however, during ablation there was a sudden onset of atrioventri- cular block of third degree, forwarded with alternating bifascicular block RBBB and left anterior or posterior hemiblock, with restitution to AV block of the second degree 3 : 2. Ablation was terminated at this point because of risk of harming conduction system. Immediate measurements straight after procedure were LVOTG 3.1 mmHg at rest and 84.4 mmHg after ventricle extrasystole. In next hours there was a restitution of conduction system to AVB of the first degree with preexisting RBBB. Nowadays the patient is without any conduction disorders of higher degree and low LVOTG still lasts. The patients after alcohol septal ablation with preexisting RBBB seem to be inappropriate candidates for ERASH procedure due to high risk of conduction disorders of higher degree as was seen in our case report.

Keywords: Endocardial radiofrequency ablation of septal hypertrophy, Left ventricle outflow tract gradient, NYHA classification, Periprocedural AV block,

Received: November 21, 2023; Revised: November 18, 2024; Accepted: December 25, 2024; Prepublished online: June 2, 2012; Published: March 1, 2025  Show citation