High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling

Abstract

Cardiac arrhythmias and conduction disturbances are accompanied by structural remodelling of the specialised cardiomyocytes known collectively as the cardiac conduction system. Here, using contrast enhanced micro-computed tomography, we present, in attitudinally appropriate fashion, the first 3-dimensional representations of the cardiac conduction system within the intact human heart. We show that cardiomyocyte orientation can be extracted from these datasets at spatial resolutions approaching the single cell. These data show that commonly accepted anatomical representations are oversimplified. We have incorporated the high-resolution anatomical data into mathematical simulations of cardiac electrical depolarisation. The data presented should have multidisciplinary impact. Since the rate of depolarisation is dictated by cardiac microstructure, and the precise orientation of the cardiomyocytes, our data should improve the fidelity of mathematical models. By showing the precise 3-dimensional relationships between the cardiac conduction system and surrounding structures, we provide new insights relevant to valvar replacement surgery and ablation therapies. We also offer a practical method for investigation of remodelling in disease, and thus, virtual pathology and archiving. Such data presented as 3D images or 3D printed models, will inform discussions between medical teams and their patients, and aid the education of medical and surgical trainees.

Relationship between the membranous septum and the virtual basal ring of the aortic root in candidates for transcatheter implantation of the aortic valve

“…The so‐called height of the membranous septum has been proposed as a potential independent predictor for periprocedural disturbances in conduction (Hamdan et al ; Maeno et al ). This hypothesis is almost certainly valid, since the shorter the membranous septum, the greater is the likelihood that the atrioventricular conduction axis will be at risk of damage during the procedures (Massing and James, ; Anderson et al ; Kawashima and Sato, ; Stephenson et al ). As we have now demonstrated, however, the location of the membranous septum itself shows significant variation relative to the plane of the virtual basal ring.…”

A rule‐based method to model myocardial fiber orientation in cardiac biventricular geometries with outflow tracts

“…However, determination of the 3D architecture of myofibers has been a challenge for anatomists among centuries. Only in the last 30 years, because of recent advances in microscopy and medical imaging, fully detailed descriptions have been obtained . Imaging techniques, such as diffusion tensor magnetic resonance imaging (DT‐MRI), micro‐CT, or X‐ray phase‐contrast imaging, make possible to acquire information about myofiber distribution.…”

“…Only in the last 30 years, because of recent advances in microscopy and medical imaging, fully detailed descriptions have been obtained. [10][11][12][13][14][15] Imaging techniques, such as diffusion tensor magnetic resonance imaging (DT-MRI), micro-CT, or X-ray phase-contrast imaging, make possible to acquire information about myofiber distribution. Unfortunately, most of these imaging techniques can only be applied on ex-vivo specimens since they need long acquisition and reconstruction times to collect accurate myofiber information.…”

Imaging of subendocardial adipose tissue and fiber orientation distributions in the human left atrium using optical coherence tomography

“…16 24 Micro CT has also been used to extract myofiber orientation from human atria at a resolution of 49 μm 3 , 25 and from the whole heart with 73 µm 3 resolution. 26 As demonstrated in these studies, high-resolution MRI and CT can provide detailed information throughout the entire cardiac chamber, particularly on fiber orientation and fibrosis. Compared to these imaging modalities, OCT offers an adjunctive imaging approach with increased resolution and the potential for real-time, in vivo imaging directly from the ablation catheter.…”

“…Contrast‐enhancement MRI has imaged fibrosis and fiber orientation within whole human atria with 180 × 180 × 360 μm 3 resolution . Micro CT has also been used to extract myofiber orientation from human atria at a resolution of 49 μm 3 , and from the whole heart with 73 µm 3 resolution . As demonstrated in these studies, high‐resolution MRI and CT can provide detailed information throughout the entire cardiac chamber, particularly on fiber orientation and fibrosis.…”