title: Increased LV apical untwist during preload reduction in healthy humans: an echocardiographic speckle tracking study during lower body negative pressure.
abstract: We sought to investigate the effect of reduced preload on left ventricle (LV) untwist and early diastolic filling in healthy individuals. Twelve healthy men, 22 (22, 23) years of age, were examined at rest and during applied lower body negative pressure (LBNP) of -20 mmHg and -40 mmHg, respectively. Regional untwist and untwist rate during IVRT were calculated at LV basal, papillary, subpapillary, and apical short axis levels by two dimensional speckle tracking echocardiography. Left ventricle early diastolic filling was assessed by transmitral E-wave (E) peak velocity by pulsed Doppler and flow propagation velocity (Vp) by color M-mode Doppler and early diastolic pulsed Doppler tissue velocities (E') from septal and lateral mitral annulus. From rest to LBNP -40 mmHg, the LV untwist and untwist rate at subpapillary level increased from 2.3 (1.4, 3.5) to 4.5 (3.1, 7.6) degrees and from -36 (-51, -25) to -69 (-127, -42) °/s (P < 0.001, P = 0.003), respectively, while apical untwist and untwist rate increased from 3.9 (2.3, 4.3) to 7.6 (6.4, 10.5) degrees and from -51 (-69, -40) to -118 (-170, -84) °/s (P < 0.001, P < 0.001), respectively. Since untwist and untwist rate at the basal level were unchanged, this created markedly larger base to apical untwist and untwist rate gradients from rest to LBNP -40 mmHg. E, Vp, and E' were reduced by 34, 32, and 39%, respectively. LV untwist and untwist rate during IVRT were increased at apical levels, which might be a physiological mechanism to minimize the impairment in LV early diastolic filling during preload reduction.
authors: Department of Cardiology B, Institute of Clinical Medicine, Oslo University Hospital, Oslo, Norway anders.hodt@medisin.uio.no.
authors: Anders
authors: A
authors: Hodt
authors: Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway Faculty of Medicine, University of Oslo, Oslo, Norway.
authors: Jonny
authors: J
authors: Hisdal
authors: Department of Cardiology, Hyogo Cancer Center, Akashi, Japan.
authors: Marie
authors: M
authors: Stugaard
authors: Section of Vascular Investigations, Oslo University Hospital, Oslo, Norway Faculty of Medicine, University of Oslo, Oslo, Norway.
authors: Einar
authors: E
authors: Stranden
authors: Department of Cardiology B, Institute of Clinical Medicine, Oslo University Hospital, Oslo, Norway.
authors: Dan
authors: D
authors: Atar
authors: Department of Cardiology, Akershus University Hospital, Oslo, Norway.
authors: Kjetil
authors: K
authors: Steine
keywords: Diastole; echocardiography; myocardial deformation; preload reduction; speckle tracking imaging