ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the nerve remodeling induced by 48 hours right atrial pacing in a canine model.</p><p><b>METHODS</b>Rapid right atrial pacing (600 beats/min) was performed in 6 mongrel dogs of either sex for 48 hours to induce sustained atrial fibrillation (AF). Six dogs without pacing served as controls. Cardiac nerves were immunocytochemically stained using anti-growth-associated protein 43 (GAP43) and anti-choline acetyltransferase (CHAT) antibodies to compare nerve sprouting and pneumogastric nerve remodeling between the 2 groups.</p><p><b>RESULTS</b>In dogs with AF, the GAP43-positive and CHAT-positive nerve densities in the left atrium, left auricular appendage, right atrium and right auricular appendage were significantly higher than in control animals (all P < 0.05). Moreover, nerve density was significantly higher in the right atrium than in the left atrium in dogs with AF. Microscopic examinations revealed an inhomogeneous distribution of cardiac nerves.</p><p><b>CONCLUSION</b>Significant nerve sprouting and pneumogastric nerve remodeling were evidenced in the right and left atrium in a canine model of sustained AF induced by 48 hours right atrial pacing.</p>