Time-Frequency Analysis of Conductive Intracardiac Communication Using a Bidirectional Electromechanical Coupling Biventricular-Pacemakers Model

Conductive Intracardiac Communication (CIC) provides a low-power data transmission approach for cardiac resynchronization therapy (CRT). However, quantitative characterization of CIC channel dynamics remains challenging because physiologically informed models that capture cardiac deformation and anatomical variability remain limited. This work establishes a closed-loop bidirectionally coupled electromechanical model in a multiphysics finite-element framework for a biventricular leadless pacemaker (BiV-LP) system. The model integrates electrophysiological activation (Aliev-Panfilov), nonlinear myocardial mechanics (Holzapfel-Gasser-Ogden), and an electro-quasi-static electromagnetic formulation to simulate CIC transmission over 100 kHz-100 MHz in a thoracic computational domain. Model plausibility was evaluated against electrophysiological and deformation data. Simulations show that CIC channel gain increases with frequency and exhibits periodic modulation over the cardiac cycle, with the largest peak-to-peak fluctuation in the MHz range. Gain variation is phase-locked to ventricular mechanics, with reduced fluctuation near end-systole and increased variation near end-diastole. Implantation location significantly influences channel stability: the right ventricular apex presents the largest fluctuation, whereas septal and outflow-tract sites exhibit improved robustness. Correlation analysis indicates that septal and outflow-tract modulation is primarily governed by local myocardial deformation, while apical variation is more sensitive to global ventricular geometry. Ex-vivo pump-driven ventricular deformation experiments support the deformation-induced CIC modulation mechanism. Static measurements confirm stable myocardial conductive coupling, and sandwich-controlled dynamic measurements demonstrate repeatable gain modulation consistent with simulation trends. These results clarify how cardiac motion and implantation position shape CIC channel dynamics and provide a physics-consistent framework for analyzing implantation-dependent CIC behavior under dynamic physiological conditions.