BACKGROUND: In normal left ventricles (LV), counterclockwise rotation (CCR) and net twist angle (NTA) have shown important roles during ejection. We investigated the effect of reduced preload by lower body negative pressure (LBNP) on CCR and NTA. METHODS AND RESULTS: Twelve healthy men were examined at rest, LBNP -20 and -40 mmHg. By two-dimensional speckle-tracking imaging, we measured rotation at four short-axis levels: basal, papillary, sub-papillary and apical. LV NTA was calculated as apex-to-base difference in rotation. Additionally, regional end-diastolic (EDA) and end-systolic area (ESA) were measured and regional area fraction (RAF) calculated [(EDA-ESA)/EDA] × 100). From rest to LBNP -40 mmHg, rotation at basal and papillary levels was unchanged. At sub-papillary level, rotation increased from 3·2 ± 3·6 to 5·8 ± 4·7° (P<0·05), while apical rotation increased from 9·3 ± 3·4 to 12·8 ± 4·7° (P<0·05). Correspondingly, LV NTA increased for each load reduction by 1·6 ± 1·8° (P<0·05) and 4·2 ± 2·3° (P<0·05). RAF increased at sub-papillary and apical levels from 57·6 ± 3·7 to 64·7 ± 8·8% and from 63·4 ± 8·8 to 74·8 ± 10·1%, respectively (P<0·05). From rest to LBNP -40 mmHg, changes in rotation and RAF correlated significantly at sub-papillary and apical levels (r = 0·94, P<0·01, and r = 0·63, P<0·05, respectively). CONCLUSIONS: Preload reduction in normal LV elicits increased systolic CCR and regional area fraction at sub-papillary and apical levels as well as net twist angle. These findings might be of physiological importance to minimize reduction in stroke volume and maintain arterial blood pressure.
BACKGROUND: In normal left ventricles (LV), counterclockwise rotation (CCR) and net twist angle (NTA) have shown important roles during ejection. We investigated the effect of reduced preload by lower body negative pressure (LBNP) on CCR and NTA. METHODS AND RESULTS: Twelve healthy men were examined at rest, LBNP -20 and -40 mmHg. By two-dimensional speckle-tracking imaging, we measured rotation at four short-axis levels: basal, papillary, sub-papillary and apical. LV NTA was calculated as apex-to-base difference in rotation. Additionally, regional end-diastolic (EDA) and end-systolic area (ESA) were measured and regional area fraction (RAF) calculated [(EDA-ESA)/EDA] × 100). From rest to LBNP -40 mmHg, rotation at basal and papillary levels was unchanged. At sub-papillary level, rotation increased from 3·2 ± 3·6 to 5·8 ± 4·7° (P<0·05), while apical rotation increased from 9·3 ± 3·4 to 12·8 ± 4·7° (P<0·05). Correspondingly, LV NTA increased for each load reduction by 1·6 ± 1·8° (P<0·05) and 4·2 ± 2·3° (P<0·05). RAF increased at sub-papillary and apical levels from 57·6 ± 3·7 to 64·7 ± 8·8% and from 63·4 ± 8·8 to 74·8 ± 10·1%, respectively (P<0·05). From rest to LBNP -40 mmHg, changes in rotation and RAF correlated significantly at sub-papillary and apical levels (r = 0·94, P<0·01, and r = 0·63, P<0·05, respectively). CONCLUSIONS: Preload reduction in normal LV elicits increased systolic CCR and regional area fraction at sub-papillary and apical levels as well as net twist angle. These findings might be of physiological importance to minimize reduction in stroke volume and maintain arterial blood pressure.
Authors: Alexandra M Williams; Rob E Shave; James M Coulson; Harriet White; Bryn Rosser-Stanford; Neil D Eves Journal: Am J Physiol Heart Circ Physiol Date: 2018-06-01 Impact factor: 4.733
Authors: Mike Stembridge; Philip N Ainslie; Michael G Hughes; Eric J Stöhr; James D Cotter; Amanda Q X Nio; Rob Shave Journal: J Appl Physiol (1985) Date: 2014-05-29
Authors: Mike Stembridge; Philip N Ainslie; Michael G Hughes; Eric J Stöhr; James D Cotter; Michael M Tymko; Trevor A Day; Akke Bakker; Rob Shave Journal: J Appl Physiol (1985) Date: 2015-03-06