Key result
Lower body negative pressure of -40 mmHg increased apical untwist from 3.9 to 7.6 degrees and untwist rate from -51 to -118 °/s compared to rest (P<0.001).
Why the study?
Does preload reduction via lower body negative pressure affect left ventricle untwist and early diastolic filling in healthy individuals?
Does preload reduction via lower body negative pressure affect left ventricle untwist and early diastolic filling in healthy individuals?
Absolute Event Rate: 7.6% vs 3.9%
p-value: p=<0.001
Preload reduction increases LV apical untwist and untwist rate, which may serve as a physiological mechanism to minimize impairment in early diastolic filling.
Preload reduction may augment apical untwist to preserve early diastolic filling; leaves open applicability in disease states.
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.
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Hodt et al. (2015) studied Healthy (n=12). Lower body negative pressure (LBNP) vs. Rest was evaluated on Apical untwist (degrees) (p=<0.001). Lower body negative pressure of -40 mmHg increased apical untwist from 3.9 to 7.6 degrees and untwist rate from -51 to -118 °/s compared to rest (P<0.001).
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