Assessment of the time constant of relaxation: Insights from simulations and hemodynamic measurements

S. De Mey*, J. D. Thomas, N. L. Greenberg, P. M. Vandervoort, P. R. Verdonck

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The objective of this study was to use high-fidelity animal data and numerical simulations to gain more insight into the reliability of the estimated relaxation constant derived from left ventricular pressure decays, assuming a monoexponential model with either a fixed zero or free moving pressure asymptote. Comparison of the experimental data with the results of the simulations demonstrated a trade off between the fixed zero and the free moving asymptote approach. The latter method more closely fits the pressure curves and has the advantage of producing an extra coefficient with potential diagnostic information. On the other hand, this method suffers from larger standard errors on the estimated coefficients. The method with fixed zero asymptote produces values of the time constant of isovolumetric relaxation (τ) within a narrow confidence interval. However, if the pressure curve is actually decaying to a nonzero pressure asymptote, this method results in an inferior fit of the pressure curve and a biased estimation of τ.

Original languageEnglish (US)
Pages (from-to)H2936-H2943
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number6 49-6
StatePublished - 2001


  • Hemodynamics
  • Left ventricular relaxation constant
  • Simulation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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