Rapid atrial pacing in a sheep model of AF caused a rapid increase in angiotensin II (from 17 to 40 pg/mL at 1 week) and a progressive increase in atrial natriuretic peptide.
Does rapid atrial pacing alter the secretion patterns of AT II and ANP in a sheep model of AF?
In a sheep model of AF, rapid atrial pacing causes early elevation of AT II and progressive elevation of ANP, which correlates with AF inducibility and atrial stretch.
INTRODUCTION: It is well established that rapid atrial rates, as in atrial fibrillation (AF), cause atrial electrical and structural remodeling leading to the maintenance of AF. The role of neurohumoral changes in this pathophysiologic vicious circle remains unclear. METHODS AND RESULTS: We followed the concentrations of angiotensin II (AT II) and atrial natriuretic peptide (ANP) in a sheep model of AF. The sheep were atrially paced at 600 beats/min for 15 weeks. Electrophysiologic study was performed at regular intervals, and venous blood samples were taken. There was a slow increase in the vulnerability for AF. The cumulative incidence of sustained AF was 80% after 15 weeks of pacing. This increased vulnerability for AF was accompanied by atrial electrical remodeling and an increase in atrial pressure. AT II increased rapidly and stayed elevated: 17+/-4 pg/mL at baseline, and 40+/-11 and 39+/-7 pg/mL after 1 and 12 weeks of pacing, respectively. ANP rose more progressively: 35+/-7 pg/mL at baseline, and 72+/-17, 95+/-10, and 106+/-23 pg/mL after 1, 3, and 12 weeks, respectively. ANP levels correlated with atrial pressure and inducibility of AF. There was no relation between these parameters and AT II levels. CONCLUSION: AT II and ANP increased significantly in this animal model of AF. Elevation of AT II occurs early and seems to be dependent on rapid atrial rate rather than the presence of AF. ANP increased more progressively. It paralleled the inducibility of AF and atrial stretch. Both neurohumoral pathways may form a potential therapeutic target for treatment of patients with AF.
Willems et al. (Sat,) conducted a other in Atrial fibrillation. Rapid atrial pacing vs. Baseline was evaluated on Concentrations of angiotensin II (AT II) and atrial natriuretic peptide (ANP) and vulnerability for AF. Rapid atrial pacing in a sheep model of AF caused a rapid increase in angiotensin II (from 17 to 40 pg/mL at 1 week) and a progressive increase in atrial natriuretic peptide.