Summary
A bioRxiv preprint presents a continuous three-dimensional structural map of a whole adult human heart at 8.01-micron isotropic voxel size. The dataset brings myocardial structure, electrical conduction tissue, blood vessels, lymphatic collectors and autonomic nerves into one spatial framework.
Researchers have produced a continuous three-dimensional structural reference of a whole adult human heart at an isotropic voxel size of 8.01 micrometres. The bioRxiv preprint, posted on September 16, 2026, uses hierarchical phase-contrast tomography to show how the heart’s muscle, electrical conduction tissue, blood vessels, lymphatic collectors and autonomic nerves are arranged within the intact organ.
Unlike conventional approaches that physically section tissue or use staining to highlight structures, the reported imaging workflow generated the reference without sectioning or staining. The resulting publicly accessible dataset is intended to support cardiac anatomy, computational modelling and future molecular atlases.
How the BigHeart map was built
The study used hierarchical phase-contrast tomography, an imaging approach that reconstructs internal structure from changes in the phase of transmitted X-rays. The 8.01-micrometre isotropic voxel size means that the reconstructed volume uses equal dimensions in all three directions, allowing structures to be examined in a consistent three-dimensional coordinate system.
That continuity is important for a complex organ in which several systems occupy the same physical space. A conventional two-dimensional section can show local anatomy, but it can make it difficult to follow a pathway across the organ or relate structures separated by depth. BigHeart instead provides a common spatial reference for tracing those relationships through the whole heart.
The researchers also performed quantitative orientation analysis of the myocardium, the muscular tissue that contracts to pump blood. They identified regional differences in the organisation of myocardial cell aggregates, adding measurements of tissue orientation to the structural reconstruction rather than relying only on visual inspection.
What the map reveals
The reconstruction traced the atrioventricular conduction axis into a distinct subendocardial Purkinje network that interfaces with the working myocardium. The atrioventricular conduction pathway carries electrical activation from the upper chambers towards the ventricles, while Purkinje fibres help distribute that activation through ventricular muscle. Mapping these structures alongside the surrounding myocardium provides a spatial basis for studying how electrical excitation is coordinated with contraction.
Integrated segmentation also showed that coronary vessels, lymphatic collectors and autonomic nerves occupy shared corridors in the epicardium, the outer layer of the heart. This places systems involved in blood supply, fluid drainage and nervous regulation within the same three-dimensional anatomical framework.
The study’s immediate contribution is therefore a reference map rather than a treatment or diagnostic result. By combining several cardiac systems in one dataset, BigHeart could help researchers construct more anatomically grounded computational models and connect later molecular measurements to precise locations in the organ. The authors also describe the dataset as a foundation for future molecular atlases, which could add information about cell types or molecular markers to the structural map.
The report is a bioRxiv preprint presenting an anatomical imaging study. Its findings describe the organisation of the imaged adult human heart; applying the observed patterns broadly across hearts, or translating the reference into clinical tools, will require further research.