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Figure 3 Relations between relaxation load sensitivity and contractility. (A) TD-Pes slope versus Ees. The data define a hyperbolic relation, with apparent increasing load dependence of tau at low contractility. (B) The same relation derived using TF. (C) A similar relation employing resting dP/dtmax as the index of contractile function, rather than Ees. This shows that the dependence did not require a specific contractility analysis parameter. (D) The same relation determined using TL. These results are markedly different from those in panels A–C, with virtually no change in the load-sensitivity despite varying Ees. (E) The same analysis employing T1/2, again showing how a simple change in the assessment method of relaxation markedly altered the appearance of enhanced load-dependence in depressed hearts. (F) A similar analysis, in which the SSD for ME versus logistic models is substitute for a tau-Pes slope ordinate. The plot is similar to panels A–C, showing that the major cause for apparent hyperbolic dependence in the latter is due to the enhanced deviation from a ME-relaxation decay with declining Ees. Ees = end-systolic elastance; ME = monoexponential; SSD = sum of the squares.
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