## 2 Materials and Methods
### Construction of Rabbit Ventricular Model with MI  
Considering the relatively high computational cost of a precise human ventricular model and the similarity in cardiac electrophysiology between rabbit and human hearts, as noted in previous studies [16; 17], we utilized a geometric model of rabbit ventricles as described in [18; 19]. This model, developed by the University of Oxford, was employed to conduct MI-related cardiac electrophysiological simulations. Briefly, the model was constructed from high-resolution magnetic resonance imaging of a rabbit's ventricle and meshed using finite element analysis, consisting of 431,990 elements and 82,619 nodes. The myocardial fiber structure was assembled, and the His-Purkinje system was manually generated using the fractal tree algorithm (Figure 2a) [20]. The ORd model was used to simulate the electrophysiological properties of the ventricular geometry [21]. The electrophysiological characteristics of the endocardi, mid-myocardi, and epicardium,  
Figure 1: Flow diagram of the overall research methodology. The blue area in the myocardial ischemia model denotes the ischemic region.  
each with equal thickness, were modified based on previous research [22] to achieve heterogeneity in cardiomyocyte electrophysiological activities. This was accomplished by decreasing the conductivities of the transit outward potassium current (I\({}_{\text{to,S}}\)) and the slow delayed rectifier potassium current (I\({}_{\text{Ks}}\)) to 25% of normal values for the endocardi and mid-myocardi, respectively, while the parameters for the epicardium remained unchanged [22]. The cardiac conduction of the His-Purkinje system in the ventricular model functioned via the DiFrancesco-Noble model.  
MI caused by left anterior descending branch occlusion was considered in this study, as shown in Figure 2b. The ventricular model, specifically the cardiac tissue, was segmented into three parts, namely the Ischemic Central Zone (ICZ), Border Zone (BZ), and Normal Zone (NZ). The MI domain was represented by a sphere encompassing the ICZ and BZ, with radii of 6000 \(\upmu\)m and 3000 \(\upmu\)m for the MI domain and the ICZ, respectively. The cardiac conduction in the ventricular model was described by the bidomain equation [23]. For the NZ, the intracellular conductivity was set at 0.174 S/m in the longitudinal direction and 0.019 S/m in the transverse direction, with extracellular conductivities of 0.62 S/m and 0.24 S/m, respectively. For the ICZ, the cellular conductivities were reduced by 50% to simulate cellular uncoupling. Additionally, the fast sodium current, L-type calcium current, slowly activated delayed rectifier potassium current, and rapidly activated delayed rectifier potassium current were reduced by 62%, 69%, 80%, and 70%, respectively [24]. The extracellular potassium ion concentration was increased to 12 mM [25]. The ATPase-sensitive potassium current was reduced by 20% [26]. These modifications collectively reproduce the effects of acidosis, hyperkalemia, and hypoxia under MI. The BZ consisted of twenty equidistant spherical shells, with the electrophysiological characteristics of each shell varying equivalently to simulate a gradient transition from the ICZ to the NZ.