Idiopathic Premature Ventricular Complexes Originating From Right Ventricular False Tendons.

Background and aims: Ablation for premature ventricular complexes (PVCs) originating from the right ventricular inflow tract (RVIT) is challenging. Few studies have identified the correlation between right ventricular false tendons (RVFTs) and RVIT PVCs. This study aimed to verify RVFTs as arrhythmogenic and electro-anatomical substrates for PVCs, and propose an enlightening mapping and ablation protocol to improve operative efficacy.

Methods: We retrospectively analyzed 63 patients with PVCs originating from the RVIT and six were found to possess arrhythmogenic RVFTs. RVFTs were identified via the intracardiac echocardiography (ICE) imaging as fibrous or fibro-muscular bands traversing the right ventricle cavity with no connection to valvular cusps. ICE was used to reconstruct the geometry of the right ventricle, and verify the successful ablation target. Moreover, morphological and histological studies of RVFTs from swine hearts were performed to reveal potential arrhythmogenic mechanisms.

Results: All RVFTs were found in the free wall of the right ventricle, with a similar connection from the subvalvular myocardium to the free wall, but with different spatial orientations, shapes, lengths, and thicknesses. Reconstruction of three-dimensional geometry with ICE was of immense benefit in terms of the location of the target spot and successful ablation. Despite variable morphology, the successful target site was consistently located at the subvalvular end of the RVFTs. Morphological and histological analysis of RVFTs from a swine heart demonstrated a component of cardiac muscles and fibrous tissues that may account for triggering activity, such as outflow tract PVCs.

Conclusion: RVFTs may serve as arrhythmogenic and electro-anatomical substrates for RVIT PVCs. The "culprit" RVFTs can be identified and reconstructed in the three-dimensional system through ICE examinations, which may improve operative efficacy.