2.1. Anatomical model

The atrial model was constructed based on a healthy adult male heart specimen obtained from Zhujiang Hospital, Southern Medical University, Guangzhou, China. The Chinese Law on Heart Research using a heart specimen has been strictly followed. The specimen was scanned using spiral computerized tomography (Philips/Brilliance 64, the Netherlands) with a resolution of 512 pixels×512 pixels and the spatial resolution was 0.3574 mm×0.3574 mm×0.3300 mm (Fig. ​(Fig.1).1). Details of the model can be found in our previous study (Deng et al., 2012a, 2012b; Gong et al., 2015).

Illustration of the atrium and torso model

(a) Anterior view of atrium; (b) Posterior view of atrium. The cyan color indicates atrial muscles, and the yellow color indicates the conduction system. (c) Conduction system; (d) Merge of the atrium into the body. LPM: left atrium pectinate muscle; BB: Bachmann bundle; VRPV: vicinity of the right pulmonary veins; SAN: sinus node; RPM: right atrium pectinate muscle; CT: crista terminalis; FO: fossa ovalis; CS: coronary sinus (Note: for interpretation of the references to color in this figure legend, the reader is referred to the web version of this article)

The conduction system in the constructed model consisted of a sinus node (SAN), crista terminalis (CT), pectinate muscle (PM), and inter atrial impulse propagation routes. The inter atrial conduction pathways included BB, VRPV, FO, and CS. The atrial fiber orientation was contained to simulate the anisotropy. The atrial cell in this study was based on the model developed by Courtemanche et al. (1998). During the activation propagation, each myocardial unit has specific electrophysiological parameters associated with the action potential (AP) of the cell unit and conduction velocity.