Endothelial Shear Stress And Blood Flow Patterns In Stroke Survivors During Submaximal Exercise

PURPOSE: Endothelial dysfunction, characterized by a decrease in nitric oxide bioavailability in vascular endothelial cells, is the first pathophysiological step for atherosclerosis, which causes 90% of cardiovascular diseases. Endothelial shear stress (ESS) is a crucial physiological stimulus to enhance endothelial function and maintain endothelial homeostasis. However, little is known about the capacity of stroke survivors to generate ESS during exercise. To the best of our knowledge, the exercise-induced blood flow patterns, including endothelial shear stress and turbulence, have yet to be determined in stroke survivors. The current study aimed to explore exercise induced differences in ESS and blood flow patterns across three different intensities between stroke survivors and a young apparently healthy population. METHODS: 31 participants (20 young and 11 stroke survivors) completed two sessions: 1) cardiopulmonary exercise test on a cycle ergometer to determine submaximal exercise intensities based on the lactate threshold and 2) blood flow patterns in the carotid artery were measured via ultrasound imaging and Doppler on a cycle ergometer during a 5 min workload steady-state exercise test at low (La of 0-2 mmol/L), moderate (La 2-4 mmol/L), and high intensity (La levels >4 mmol/L). RESULTS: There was a significant difference in the young apparently healthy population ESS in high intensity (66.3 ± 19.7 dynes/cm2) vs baseline (42.5 ± 10.5 dynes/cm2) (p < .0001) and baseline vs moderate (59.2 ± 14.3 dynes/cm2) (p < 0.005) and Reynolds (Re) number (AU) showed turbulent flow for all intensities. Stroke survivor’s ESS only demonstrated a significant difference between baseline (18.9 ± 5.06 dynes/cm2) and high intensity (41.4 ± 10.3 dynes/cm2) (p < 0.01) and Re number (AU) demonstrated a turbulent flow for all intensities. Within comparisons demonstrated significant differences between young and stroke survivors during baseline (p = 0.003) and high intensity (p = 0.0007). CONCLUSIONS: Stroke survivors produced turbulent flow and low levels of ESS in all intensities. Future studies should focus on the chronic effect of endurance exercise on ESS and stroke survivors. Supported by: Research reported in this abstract was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number SC2GM140952