Persistent alterations in heart rate variability, baroreflex sensitivity, and anxiety-like behaviors during development of heart failure in the rat

1 Department of Pharmacology and 2 The Cardiovascular Institute, Loyola University Chicago, Stritch School of Medicine, Maywood, Illinois Submitted 27 November 2007 ; accepted in final form 29 April 2008 Depressed heart rate variability and mood are associated with increased mortality in patients with congestive heart failure (CHF). Here autonomic indexes were assessed 3 and 7 wk after left coronary artery ligation in telemetered rats, after which anxiety-like behaviors were assessed in an elevated plus maze. Low frequency (LF) and high frequency (HF) heart rate variability were reduced in CHF rats 3 wk after infarction (LF, 1.60 ± 0.52 vs. 6.97 ± 0.79 ms 2 ; and HF, 1.53 ± 0.39 vs. 6.20 ± 1.01 ms 2 ; P < 0.01). The number of sequences of interbeat intervals that correlated with arterial pressure was decreased in CHF rats at 3 and 7 wk ( week 3 , 26.60 ± 10.85 vs. 59.75 ± 11.4 sequences, P < 0.05; and week 7 , 20.80 ± 8.97 vs. 65.38 ± 5.89 sequences, P < 0.01). Sequence gain was attenuated in CHF rats by 7 wk (1.34 ± 0.06 vs. 2.70 ± 0.29 ms/mmHg, P < 0.01). Coherence between interbeat interval and mean arterial blood pressure variability in the LF domain was reduced in CHF rats at 3 (0.12 ± 0.03 vs. 0.26 ± 0.05 k 2 , P < 0.05) and 7 (0.16 ± 0.02 vs. 0.31 ± 0.05 k 2 , P < 0.05) wk. CHF rats invariably entered the open arm of the elevated plus maze first and spent more time in the open arms (36.0 ± 15% vs. 4.6 ± 1.9%, P < 0.05). CHF rats also showed a tendency to jump head first off the apparatus, whereas controls did not. Together the data indicate that severe autonomic dysfunction is accompanied by escape-seeking behaviors in rats with verified CHF. telemetry; blood pressure; elevated plus maze; myocardial infarction; congestive heart failure Address for reprint requests and other correspondence: K. Scrogin, Dept. of Pharmacology, Loyola Univ. Stritch School of Medicine, 2160 S. First Ave., Maywood, IL 60153 (e-mail: kscrogi{at}lumc.edu )