Left Ventricular Ejection Time Measured by Echocardiography Differentiates Neurobehavioral Resilience and Vulnerability to Sleep Loss and Stress

Abstract

There are substantial individual differences (resilience and vulnerability) in performance resulting from sleep loss and psychosocial stress, but predictive potential biomarkers remain elusive. Similarly, marked changes in the cardiovascular system from sleep loss and stress include an increased risk for cardiovascular disease. It remains unknown whether key hemodynamic markers, including left ventricular ejection time (LVET), stroke volume (SV), heart rate (HR), cardiac index (CI), blood pressure (BP), and systemic vascular resistance index (SVRI), differ in resilient vs. vulnerable individuals and predict differential performance resilience with sleep loss and stress. We investigated for the first time whether the combination of total sleep deprivation (TSD) and psychological stress affected a comprehensive set of hemodynamic measures in healthy adults, and whether these measures differentiated neurobehavioral performance in resilient and vulnerable individuals. Thirty-two healthy adults (ages 27–53; 14 females) participated in a 5-day experiment in the Human Exploration Research Analog (HERA), a high-fidelity National Aeronautics and Space Administration (NASA) space analog isolation facility, consisting of two baseline nights, 39 h TSD, and two recovery nights. A modified Trier Social Stress Test induced psychological stress during TSD. Cardiovascular measure collection [SV, HR, CI, LVET, BP, and SVRI] and neurobehavioral performance testing (including a behavioral attention task and a rating of subjective sleepiness) occurred at six and 11 timepoints, respectively. Individuals with longer pre-study LVET (determined by a median split on pre-study LVET) tended to have poorer performance during TSD and stress. Resilient and vulnerable groups (determined by a median split on average TSD performance) showed significantly different profiles of SV, HR, CI, and LVET. Importantly, LVET at pre-study, but not other hemodynamic measures, reliably differentiated neurobehavioral performance during TSD and stress, and therefore may be a biomarker. Future studies should investigate whether the non-invasive marker, LVET, determines risk for adverse health outcomes.

Impact of bimonthly repeated total sleep deprivation and recovery sleep on cardiovascular indices

“…By contrast, our prior study found that one night of TSD significantly increased LVET, SBP, and DBP but did not produce any significant alterations in CI or SVRI (Yamazaki, Rosendahl-Garcia, et al, 2022). Differences between the current study and our prior study (Yamazaki, Rosendahl-Garcia, et al, 2022) may be due to that study's shorter duration, single exposure to TSD, or different environmental study conditions, among other factors. Our results were consistent with some prior studies from other groups (Kato et al, 2000;Sunbul et al, 2014;Zhong et al, 2005), but not others (Cernych et al, 2021;Kato et al, 2000;Krause et al, 2023;Kuetting et al, 2019;Mikulski et al, 2006;Papacocea et al, 2019;Sauvet et al, 2010;Sunbul et al, 2014;Zhong et al, 2005).…”

“…The average value of three consecutive readings, taken one minute apart, was used for analyses. SVRI was calculated by assuming that central venous pressure was zero and by using the following equations (Klabunde, 2012; Norsk et al., 2015; Yamazaki, Rosendahl‐Garcia, et al., 2022):$$$$ \mathrm{Mean}\ \mathrm{arterial}\ \mathrm{pressure}=\left(\mathrm{SBP}+{2}^{\ast}\mathrm{DBP}\right)/3 $$$$$$$$ \mathrm{SVRI}=\mathrm{mean}\ \mathrm{arterial}\ \mathrm{pressure}/\mathrm{CI} $$$$…”

“…In addition, CV measures were collected pre-study, which occurred a few days before the beginning of the 4-month or 8-month studies. SV, CI, SVRI, SBP, LVET, HR, DBP, and MAP were collected under highly controlled and fasted conditions at all time points including pre-study, with collections completed between 0700 and 1200 h. Notably, all CV measures were within the ranges reported for healthy adults (Cattermole et al, 2017;Klabunde, 2012;Shaffer & Ginsberg, 2017;Yamazaki, Rosendahl-Garcia, et al, 2022).…”

“…The LVOT was imaged from the parasternal long-axis view while the participants were semi-supine in a left lateral decubitus posture T A B L E 1 Actigraphic sleep data before and during the 5-day experiments at month 2 and at month 4. (Yamazaki, Rosendahl-Garcia, et al, 2022). Three to four, two-second cine-loops of dynamic motion of the LVOT were digitally saved.…”

“…Continuous wave Doppler signals were taken from the ascending aorta at the suprasternal notch in a seated posture (Yamazaki, Rosendahl-Garcia, et al, 2022). Three five-second cineloop sweeps of continuous wave Doppler data were collected and digitally stored as proprietary raw data (Yamazaki, Rosendahl-Garcia, et al, 2022). A professional sonographer (K.M.R-G) conducted formal analyses of the echocardiography data.…”