New manifestations of electrophysiological remodeling of heart during experimental model of atrial fibrillation in cirrhotic rat isolated heart

Introduction: The present study is aimed to evaluate electrophysiological remodeling of atrioventricular (AV) node and ventricular conduction during experimental atrial fibrillation (AF) model in isolated heart of cirrhotic rats. Methods: Cirrhosis-induced electrophysiological remodeling was evaluated in 24 isolated retrogradely perfused rat hearts in 2 groups (control and cirrhotic). Cirrhosis was induced after 6 weeks of common bile duct ligation in rats. Extracellular filed potential was recorded from upper atrium and right ventricle. The conduction time, refractoriness and frequency-dependent properties of AV node were characterized by specific stimulation protocols. Experimental AF was simulated by high-rate atrial pacing with random coupling intervals (range 75–125 ms). Results: Nodal conduction time and ventricular responsiveness were significantly increased in the cirrhotic rats compared to the control (95.8 ± 4.2 ms vs. 78.8 ± 3.3 ms) (P< 0.05). Nodal protective function during AF was potentiated with increased R-R interval, concealed beats, ventricular refractoriness and zone of concealment in the cirrhotic group. Cirrhosis evoked rate–dependent ventricular conduction time shortening with different patterns during arrhythmia. Conclusion: Cirrhosis-induced electrophysiological remodeling was shown by increased AV nodal conduction and shortened ventricular conduction. This electrophysiological remodeling may be considered as a new manifestation of cirrhotic cardiomyopathy in the heart, which can change ventricular rhythm during arrhythmia.