Basic Science and Experimental Studies
Circadian Body Temperature Variability is an Indicator of Poor Prognosis in Cardiomyopathic Hamsters

https://doi.org/10.1016/j.cardfail.2009.11.004Get rights and content

Abstract

Background

Low body temperature is an independent predictor of poor prognosis in patients with congestive heart failure. The cardiomyopathic hamster develops progressive biventricular dysfunction, resulting in heart failure death at 9 months to 1 year of life. Our goal was to use cardiomyopathic hamsters to examine the relationship between body temperature and heart failure decompensation and death.

Methods and Results

To this end, we implanted temperature and activity transducers with telemetry into the peritoneal space of 46 male Bio-TO-2 Syrian cardiomyopathic hamsters. Multiple techniques, including computing mean temperature, frequency domain analysis, and nonlinear analysis, were used to determine the most useful method for predicting poor prognosis. Data from 44 hamsters were included in our final analysis. We detected a decline in core body temperature in 98% of the hamsters 8 ± 4 days before death (P < .001). We examined the dominant frequency of temperature variation (ie, the circadian rhythm) by using cosinor analysis, which revealed a significant decrease in the amplitude of the body temperature circadian rhythm 8 weeks before death (0.28°C; 95% CI, 0.26-0.31) compared to baseline (0.36°C; 95% CI, 0.34-0.39; P = .005). The decline in the circadian temperature variation preceded all other evidence of decompensation.

Conclusions

We conclude that a decrease in the amplitude of the body temperature circadian rhythm precedes fatal decompensation in cardiomyopathic hamsters. Continuous temperature monitoring may be useful in predicting preclinical decompensation in patients with heart failure and in identifying opportunities for therapeutic intervention.

Section snippets

Animals

This study was approved and conducted according to the guidelines of the University of Texas Health Science Center Animal Welfare Committee. Each hamster was housed separately in an airtight plastic cage. The cages were placed in a modified cage rack (Alternative Designs, Inc, Siloam Springs, AR) that was equipped with a blower to provide air circulation and a hydration system to provide fresh water. We continuously monitored the temperatures in empty cages attached to the rack to ensure that

Results

Data from 44 hamsters were included in our final analysis. The average survival time of the hamsters was 365 ± 41 days (from birth to death). Plots of the Kaplan-Meier estimates of conditional probability of survival to a given age in the experimental and control groups of hamsters are shown in Fig. 1. The hamsters weighed an average of 108.9 ± 9.5 g at baseline (after transmitter implantation) and 132.8 ± 21.3 g at death.

Discussion

In addition to the consistent temperature decline seen 8 ± 4 days before death in the majority of cardiomyopathic hamsters, we observed that the amplitude of the body temperature circadian rhythm was significantly lower 8 weeks before death than at baseline.

Heart failure is a complex clinical syndrome characterized by physiologic compensatory efforts that become pathologic, centering on sympathetic neurohormonal activation. Sympathetic reflex dominance is associated with a loss of reflex

Conclusions

We observed that declining body temperature variability predicted decompensation or death in cardiomyopathic hamsters. By using frequency domain analysis, we saw a loss in temperature variability before changes in body weight or physical activity occurred, suggesting that this analysis may be a useful means of identifying opportunities for therapeutic intervention. More studies are necessary to determine whether the interventions known to influence outcomes in heart failure can affect animals

Acknowledgments

We would like to thank Hilary Marks, PhD, for editorial assistance in the preparation of this manuscript.

References (33)

  • D.K. Amin et al.

    Comparative hemodynamic effects of intravenous dobutamine and MDL-17,043, a new cardioactive drug, in severe congestive heart failure

    Am Heart J

    (1985)
  • F.G. Shellock et al.

    Prevalence of brown adipose tissue in chronic congestive heart failure secondary to coronary heart disease

    Am J Cardiol

    (1985)
  • M.E. Young et al.

    Potential role for peripheral circadian clock dyssynchrony in the pathogenesis of cardiovascular dysfunction

    Sleep Med

    (2007)
  • E. Bajusz et al.

    Spontaneous, herditary myocardial degeneration and congestive heart failure in a strain of Syrian hamsters

    Ann N Y Acad Sci

    (1969)
  • F. Homburger et al.

    New hereditary disease of Syrian hamsters: primary, generalized polymyopathy and cardiac necrosis

    Arch Intern Med

    (1962)
  • W. Nelson et al.

    Methods for cosinor-rhythmometry

    Chronobiologia

    (1979)
  • Cited by (0)

    The authors have no conflicts of interest.

    The Texas Training and Technology for Trauma and Terrorism (T5) Program, supported by the US Army's Telemedicine & Advanced Technology Research Center (TATRC), sponsored portions of this research.

    View full text