Effects of Chronic Renal Insufficiency Combined with Atrial Fibrillation on Left Atrial Endothelial Function in a Beagle Model

The co-occurrence of atrial fibrillation (AF) and renal insufficiency (RI) represents a clinically complex phenomenon with high prevalence. This study investigated the impact of chronic moderate RI combined with AF on left atrial endothelial function in beagles. Chronic RI was induced by transcatheter embolization of the main branch of the left renal artery using gelatin sponge granules, with animals maintained for 3 months to allow chronic renal parenchymal damage to develop. AF was subsequently induced by continuous rapid atrial pacing (basic cycle length, 60 ms; voltage, 4 times the diastolic pacing threshold; 180 min). Histological changes were assessed using hematoxylin and eosin staining. Parameters associated with endothelial function, coagulation, fibrinolysis, inflammation, and renin-angiotensin-aldosterone system (RAAS) activity in plasma and heart tissues were examined using enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, and western blotting. The results demonstrated successful establishment of a chronic kidney damage model with moderate RI, confirmed by significantly elevated plasma creatinine, urea nitrogen, and reduced creatinine clearance. Left atrial endothelial function was significantly impaired in beagles with combined RI and AF, accompanied by enhanced procoagulant effects and decreased fibrinolysis. Inflammatory markers were elevated following the RI procedure or AF induction and were further enhanced in the combined RI+AF group. Additionally, RAAS activity, evidenced by increased renin and aldosterone levels, was elevated following RI and further augmented upon combination with AF. In summary, this study successfully established an in vivo animal model of chronic moderate RI combined with AF in beagles, demonstrating that this combination significantly disturbed left atrial endothelial function and increased thrombotic risk.