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[Preload and ventricular lusitropism; logistic and monoexponential function fittings].

Authors
  • Mizuno, Ju
  • Hanaoka, Kazuo
  • Suga, Hiroyuki
Type
Published Article
Journal
Masui. The Japanese journal of anesthesiology
Publication Date
Aug 01, 2006
Volume
55
Issue
8
Pages
956–962
Identifiers
PMID: 16910474
Source
Medline
License
Unknown

Abstract

A logistic function has been found to fit the isovolumic left ventricular (LV) relaxation pressure curve and the isometric relaxation force curve of the papillary muscle much more precisely than the conventional monoexponential function. Therefore, the logistic time constant (tauL) has been proposed as a better index of the rate of cardiac relaxation or lusitropism than the conventional monoexponential time constant (tauE). Many investigators have reported that tauE changes with preloading. We analysed and compared the effect of LV volume (LVV) loading on both logistic and monoexponential fittings and their time constants of the isovolumic LV relaxation pressure curve in the excised, cross-circulated canine hearts. We found that the logistic fitting was superior to the monoexponential fitting at any LVV. LVV loading did not affect tauL at all but affected tauE slightly. The logistic fitting more reliably characterises the lusitropism than the monoexponential fitting, and tauL, serving as a more reliable ventricular lusitropism index, is independent of changes in LVV loading or the Frank-Starling effect.

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