SYM-01: Bioengineering the Heart

STRUCTURAL CHARACTERISTIC OF HUMAN ATRIA AND ITS IMPLICATION IN ATRIAL FIBRILLATION

Jichao Zhao, Yufeng Wang, Alan Tang

The University of Auckland, New Zealand

Atrial fibrillation (AF) is characterized by rapid or irregular electrical activity in the upper chambers of the heart. AF is the most common cardiac arrhythmias. Recent studies suggest that the anatomical structure of human atria plays a key role in initializing and sustaining AF, of which atrial wall thickness variation is an important factor neglected in the past.  Recently it is believed to influence AF activation patterns due to the source-sink mismatch. Furthermore, it may be an important indicator in determining the precise ablation region and predicting ablation outcomes. Estimating the 3D wall thickness across two atrial chambers in human hearts is a challenging task due to the inherited complex and thin atrial wall atrial geometries.  
In this study, we have developed a novel Laplace approach to estimate the 3D wall thickness of the biatrial chambers. For atrial chamber geometry, we adopt the most established human atrial anatomical model imaged using MRI with a resolution of 0.33 mm3 of the Visible Female dataset (59 year old), as well as two Gadolinium-enhanced MRI dataset of in-vivo patients with AF with 1.25x1.25x2.5mm3 using 3T whole body scan from the Utah University. To estimate the 3D wall, first of all, atrial chambers will be closed. Then a region growing approach will be used to detect epicardial and endocardial surfaces, respectively. Finally, by solving the system of Laplace equation twice, we can obtain a robust 3D wall thickness solution for the two atrial chambers.
Our results indicate dramatic wall thickness variation in both chambers, especially in right atrium. This study suggests that the proposed Laplace solver is efficient and robust to estimate wall thickness throughout the atrial chambers by comparing with other approaches including center-surface, shortest distance and normal based approaches. The other structural characteristics of human atria is also reported in this study.

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