Figure 1.

Schematic diagram illustrating study design, timeline and interventions. Chronic heart failure (CHF) model was induced by surgical ligation of the left coronary artery in rats. Sham rats underwent the same surgery without left coronary ligation. Implantation of the ECG telemeter and labeling of atrioventricular ganglion (AVG) neurons were performed on the day following 2, 7, or 13 weeks after left coronary ligation (CHF groups) or same surgery (Sham groups). One week after implantation of the ECG telemeter, ECG signals were continuously acquired for 24 h in conscious rats. Terminal experiments including measurement of inducibility of ventricular arrhythmia, measurement of vagal control of ventricular function, hemodynamic and morphological measurements, and patch-clamp recording for N-type Ca²⁺ currents were performed at 3, 8, and 14 weeks after left coronary ligation (CHF groups) or sham surgery (Sham groups), respectively.