Females have greater left ventricular twist mechanics than males during acute reductions to preload

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Author
Williams, Alexandra
Shave, Rob
Stembridge, Mike
Eves, Neil
Date
2016-07-01Acceptance date
2016-05-09
Date Deposited
2016-06-08
Type
Article
acceptedVersion
Publisher
American Physiological Society
ISSN
0363-6135
1522-1539 (ESSN)
Metadata
Show full item recordAbstract
Background—Compared to males, females have smaller left ventricular (LV) dimensions and volumes, higher ejection fractions (EF), and higher LV longitudinal and circumferential strain. LV twist mechanics determine ventricular function, and are preload-dependent. Therefore, the sex differences in LV structure and myocardial function may result in different mechanics when preload is altered. This study investigated sex differences in LV mechanics during acute challenges to preload.
Methods and Results—Using conventional and speckle-tracking echocardiography, LV structure and function were assessed in 20 males (24 ± 6.2 yr) and 20 females (23 ± 3.1 yr) at baseline and during progressive levels of lower body negative pressure (LBNP). Fourteen participants (8 males, 6 females) were also assessed following a rapid infusion of saline. LV end-diastolic volume, end-systolic volume, stroke volume (SV) and EF were reduced in both groups during LBNP (p<0.001). While males had greater absolute volumes (p<0.001) there were no sex differences in allometrically scaled volumes at any stage. Sex differences were not detected at baseline in basal rotation, apical rotation, or twist. Apical rotation and twist increased in both groups (p<0.001) with LBNP. At -60 mmHg, females had greater apical rotation (p=0.009), twist (p=0.008) and torsion (p=0.002), and faster untwisting velocity (p=0.02) than males. There were no differences in mechanics following saline infusion.
Conclusions— Females have larger LV twist and a faster untwisting velocity than males during large reductions to preload, supporting that females have a greater reliance on LV twist mechanics to maintain SV during severe reductions to preload.
Journal/conference proceeding
American Journal of Physiology - Heart and Circulatory Physiology
Citation
Williams, A. M., Shave, R., Stembridge, M. & Eves, N. (2016) 'Females have greater left ventricular twist mechanics than males during acute reductions to preload', American Journal of Physiology - Heart and Circulatory Physiology, 311 (1), pp. 76-84
Description
This article was published in American Journal of Physiology - Heart and Circulatory Physiology on 13 May 2016 (online), available at http://dx.doi.org/10.1152/ajpheart.00057.2016
Sponsorship
This study was funded by the Natural Sciences and Engineering Research Council of Canada. A.M.W. is supported by the Natural Sciences and Engineering Research Council of Canada. N.D.E. is supported by the Michael Smith Foundation for Health Research
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