Load Dependence of Relaxation

Brutsaert, Dirk L.; Sys, Stanislas U.

doi:10.1007/978-1-4615-6832-2_10

Cited by 4 publications

(1 citation statement)

References 21 publications

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“…contraction load is reduced, crossbridge cycling proceeds faster, possibly, because of reduced affinity of troponin-C for calcium. 44 Isometric relaxation of a contraction with low muscle load, therefore, starts earlier than isometric relaxation of a contraction with high muscle load. When muscle load is sufficiently lowered so that end-systolic muscle length drops below 0.94 lmax, isometric relaxation will start at a time when calcium removal is still incomplete.…”

Section: Effects Of Combined Aortic Valvuloplasty-arterialmentioning

confidence: 99%

Wide-range load shift of combined aortic valvuloplasty-arterial vasodilation slows isovolumic relaxation of the hypertrophied left ventricle.

Paulus¹,

Heyndrickx²,

Buyl³

et al. 1990

Circulation

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To assess the effects of left ventricular (LV) load on isovolumic relaxation rate of the hypertrophied LV, wide range LV load shifts were imposed by the sequential use of balloon aortic valvuloplasty (BAV) Phase-plane plots (LV dP/dt vs. LVP) of the LV pressure (P) signal during isovolumic relaxation were constructed for the four different loading states by matching corresponding LVP and LV dP/dt points. For a given LVP value, the corresponding LV dP/dt values on the phase plane plots were comparable before BAV, during NIT before BAV, and after BAV. The corresponding LV dP/dt value was higher during NIT after BAV, implying a slower relaxation rate at the same LVP after sequential BAV-NIT. A shift in the control of isovolumic LV relaxation kinetics from myofilamentary detachment to myoplasmic calcium removal, which proceeds slower in hypertrophied myocardium, could explain the observed slowing of LV isovolumic relaxation after drastic LV unloading of sequential BAV-NIT. (Circulation 1990;81:886-898) T N he effects of left ventricular (LV) load on the slows isovolumic LV pressure decline.1-4 In normal time course of isovolumic LV pressure decay control subjects or in patients with aortic stenosis, remain controversial. In animal experiments, similar interventions fail to change the time constant a rise of LV load by volume loading, infusion of of isovolumic LV pressure decay.5,6 vasopressors, or mechanical occlusion of the aortaThe effects of LV load on the onset and time course of LV pressure decline are important because From the Cardiovascular Center, Aalst, Belgium. they reveal whether relaxation kinetics are controlled

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Section: Effects Of Combined Aortic Valvuloplasty-arterialmentioning

confidence: 99%