Abstract
Left ventricular systolic stiffness was measured by rapidly changing ventricular volume (within 7 ms) of isovolumically contracting isolated rabbit hearts. Instantaneous pressure-volume relations were found to be linear with slopes that depended upon the moment during contraction at which the volume change was induced. These slopes were proportional to the total pressure developed in the ventricle just prior to the volume change. The same was found when the time course of pressure was influenced by changing the Ca++ content of the perfusate. An influence, however, also could be detected when end-diastolic volume was changed. At the same pre-release pressure a greater volume caused a decrease of active stiffness. The results indicate the possiblity of an active component in ventricular systolic stiffness.
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Abbreviations
- Nr.:
-
number of experiment
- H.W.:
-
heart weight (g)
- EDP:
-
enddiastolic pressure (mm Hg)
- \(\frac{{{\text{Ca}}^{{\text{ + + }}} :}}{{\Delta P/\Delta {\text{V:}}}}\) :
-
Ca++-content of the perfusate (mEq/l) mean value of stiffness in systole in the part of pressure curve which was explored (mm Hg/ml)
- N :
-
number of different times during systole at which QVR were applied
- P max :
-
maximal pressure of the undisturbed pressure curve (mm Hg)
- ΔV0 :
-
inverted slope of the stiffness-pressure relations (ml)
- SEM:
-
standard error of the mean in ΔV0
- \(\frac{{\Delta P}}{{\Delta V}}\left( {{\text{P}}_{\text{2}} = 0} \right)\) :
-
intercept on ΔP/ΔV axis of the stiffness pressure relation (mm Hg/ml)
- SEE:
-
standard error of the estimate in\(\frac{{\Delta P}}{{\Delta V}}\left( {{\text{P}}_{\text{2}} = 0} \right)\)
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Schiereck, P., Boom, H.B.K. Left ventricular active stiffness: dependency on time and inotropic state. Pflugers Arch. 374, 135–143 (1978). https://doi.org/10.1007/BF00581294
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DOI: https://doi.org/10.1007/BF00581294