First in situ 3D visualization of the human cardiac conduction system and its transformation associated with heart contour and inclination

Tomokazu Kawashima,Fumi Sato

doi:10.1038/s41598-021-88109-7

Abstract

Current advanced imaging modalities with applied tracing and processing techniques provide excellent visualization of almost all human internal structures in situ; however, the actual 3D internal arrangement of the human cardiac conduction system (CCS) is still unknown. This study is the first to document the successful 3D visualization of the CCS from the sinus node to the bundle branches within the human body, based on our specialized physical micro-dissection and its CT imaging. The 3D CCS transformation by cardiac inclination changes from the standing to the lying position is also provided. Both actual dissection and its CT image-based simulation identified that when the cardiac inclination changed from standing to lying, the sinus node shifted from the dorso-superior to the right outer position and the atrioventricular conduction axis changed from a vertical to a leftward horizontal position. In situ localization of the human CCS provides accurate anatomical localization with morphometric data, and it indicates the useful correlation between heart inclination and CCS rotation axes for predicting the variable and invisible human CCS in the living body. Advances in future imaging modalities and methodology are essential for further accurate in situ 3D CCS visualization.

Highlights

Current advanced imaging modalities with applied tracing and processing techniques provide excellent visualization of almost all human internal structures in situ; the actual 3D internal arrangement of the human cardiac conduction system (CCS) is still unknown
Our 3D images clearly showed that the bundle branches do not bifurcate simultaneously from the branching bundle of His (BBH); instead, the BBH completely branched off the left bundle branch (LBB) like a thin drape and formed the right bundle branch (RBB) (Fig. 1g–i)
Our analysis identified two misunderstandings about the anatomical CCS localization: (1) The BBH runs along the inferoanterior border of the membranous septum, unlike the previous concept that it runs along the lower edge

Summary

Introduction

Current advanced imaging modalities with applied tracing and processing techniques provide excellent visualization of almost all human internal structures in situ; the actual 3D internal arrangement of the human cardiac conduction system (CCS) is still unknown. In situ CCS mapping can provide accurate anatomical information, improve the understanding of the normal and abnormal conduction mechanisms, and help in evolving better strategies for improving pacing and ablation outcomes. The left bundle branch was shown as the left chamber view, and the other AV conduction axis as the right chamber view In this context, imaging the CCS from any direction is difficult because of a limited 2D photographic presentation depending on the dissection.

Methods

Results

Conclusion