599Preload reduction in healthy humans elicits a reduction in LV diastolic relaxation and filling, while apical rotation and untwist increases

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Purpose: The influence of changes in preload on LV function is controversial. We wanted to investigate the effect of reduced preload on LV filling, relaxation, rotation and untwist in healthy individuals.Methods: 11 healthy men, 23± 2 years of age, were examined at rest and lower body negative pressure (LBNP) -20 mmHg and -40 mmHg. Stroke volume was measured 1-2 cm above the aortic valve with pulsed Doppler from the suprasternal position. The LV diastolic filling was assessed by transmitral early E velocity, flow propagation velocity (Vp) by color M-mode Doppler and LV relaxation by a mean value of early diastolic pulsed Doppler tissue velocity from septal and lateral mitral annulus, E`. Finally, LV end-systolic rotation and untwist ((rotation at end-systole minus rotation at MVO)/rotation at end-systole)), at basal and apical short axis levels were measured by 2D speckle tracking imaging.Results: See table 1.Conclusions: Preload reduction elicits a reduction in LV relaxation and early dastolic filling. Similar to an increase in apical systolic twist, there was an increase in apical untwist during IVRT, which might be of physiological importance to minimize the impairment in LV diastolic filling during preload reduction.

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