Heart rate variability in rats with aldosterone-induced chronic heart failure

The renin-angiotensin-aldosterone system contributes to the pathophysiology of chronic heart failure. In this study, chronic heart failure is gradually induced in uninephrectomized rats (n = 4) by aldosterone infusion (0.75 mug/h) and high Na and low Mg diet for four weeks followed up by high Na and low Mg diet alone for an additional six weeks. A control rat (n = 1) is untreated and unoperated. Electrocardiograms were recorded continuously during the entire experiment. Time and frequency domain heart rate variability (HRV) parameters are computed to study the long-term trends of heart rate and HRV. The results show that aldosterone infusion decreases heart rate and circadian variability in the treatment rats. After stopping aldosterone infusion, heart rate increases with less circadian variability. ANOVA indicates change of heart rate (p < 0.001) during and after aldosterone infusion periods (within each treatment rat).