Load dependence of isovolumic relaxation in intact heart: Facts or artifacts

S. Perlini, F. Soffiantino, C. Farilla, P. Solda, A. Calciati, M. Paro, G. Finardi, L. Bernardi

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In order to study the dependence of left ventricular isovolumic relaxation on preload, afterload, and contractility the effects of infusions of dextran, phenylephrine, and dobutamine were assessed in 10 closed chest anaesthetised dogs. Left ventricular and aortic pressures and left ventricular transverse diameters were measured by micromanometers and a tracking sonomicrometer. Isovolumic relaxation time constant was computed by two different single exponential models: the first (time constant Tw) assumed the horizontal asymptote as equal to zero, whereas the second (time constant Tl) assumed a variable asymptote (Pb). To compare the two models, deviations between observed and predicted left ventricular pressures during isovolumic relaxation were computed for both (average squared difference ARSSQw and ARSSQl respectively). Dextran infusion, although increasing preload indexes, did not affect Tl (from 35.1 (2.6) to 38.5 (2.2)ms, NS) (mean (SEM)), but increased Tw (from 28.4 (1.4) to 43.8 (2.1) ms, p

Original languageEnglish
Pages (from-to)47-54
Number of pages8
JournalCardiovascular Research
Issue number1
Publication statusPublished - 1988

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Physiology (medical)
  • Physiology


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