Passive leg movement‐induced hyperaemia with a spinal cord lesion: evidence of preserved vascular function

Abstract

A spinal cord injury (SCI) clearly results in greater cardiovascular risk, however, accompanying changes in peripheral vascular structure below the lesion, mean the real impact of a SCI on vascular function is unclear. Therefore, utilizing passive leg movement-induced (PLM) hyperemia, an index of nitric oxide (NO)-dependent vascular function, and the central hemodynamic response to this intervention, we studied 8 individuals with a SCI, and 8 age-matched controls (CTRL). Specifically, we assessed heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), leg blood flow (LBF), and thigh composition. In CTRL, passive movement, transiently decreased MAP, and increased HR and CO from baseline by 2.5±1 mmHg, 7±2 bpm, and 0.5±0.1 l/min respectively. In SCI, HR and CO responses were unidentifiable. LBF increased to a greater extent in CTRL (515±41 Δml/min) compared to SCI, (126±25 Δml/min) (p<0.05). There was a strong relationship between ΔLBF and thigh muscle volume (r = 0.95). After normalizing ΔLBF for this strong relationship (ΔLBF/muscle volume), there was evidence of preserved vascular function in SCI (CTRL: 120±9; SCI 104±11 ml/min/l). A comparison of ΔLBF in the passively moved and stationary leg, to partition the contribution of the blood flow response, implied that 35% of the hyperemia resulted from cardioacceleration in the CTRL, whereas all the hyperemia appeared peripheral in origin in the SCI. Thus, utilizing PLM-induced hyperemia as marker of vascular function, it is evident that peripheral vascular impairment is not an obligatory accompaniment to a SCI.

Aerobic training status does not attenuate prolonged sitting-induced lower limb vascular dysfunction

“…Taken together, these results may highlight the potential impact of varying interindividual thigh volume and muscle mass on the PLM-induced hyperemic response. Thigh muscle mass has been noted as a potential confounding factor owing to the likely role of vascular density in the PLM-induced hyperemic response (Gifford and Richardson 2017;Venturelli et al 2014), and previous studies have normalized PLMinduced hyperemia to thigh volume to better evaluate leg vascular function (Groot et al 2013). The current study used this approach and although normalization of the PLM responses to thigh volume resulted in greater differences between the 2 groups ( Fig.…”

The effect of passive lower limb training on heart rate asymmetry

“…However, this conclusion must be drawn cautiously in the future work due to a considerable part of the weak coefficients, which indicted that HRA and HRV were correlated but had distinct metrics in assessing intricate and nonlinear autonomic system. Another reason for the weak correlation might due to the hemodynamic responses to passive training, i.e., passive training led to heart rate increase and an enhancement in cardiac output [23][24][25].…”

Impact of Nitric Oxide Bioavailability on the Progressive Cerebral and Peripheral Circulatory Impairments During Aging and Alzheimer's Disease

“…where blood flow is in milliliters per minute. To perform muscle and brain volume effect-corrections, mostly related to the lower limb muscle and brain atrophy, FA and ICA blood flow were normalized to leg muscle volume (thigh + lower leg volume) and total brain tissue volume (cortical, subcortical GM and WM volumes, including the brainstem and cerebellum), respectively (Liu et al, 2014 ; Venturelli et al, 2014 ). All scanning and blinded analyses were performed by experienced and skilled sonographers.…”

“…Therefore, we have adopted this noninvasive and reliable method to determine endothelial NO bioavailability. Moreover, the PLM protocol has been successfully adopted to determine systemic vascular function in healthy young (Mcdaniel et al, 2010a ), elderly (Mcdaniel et al, 2010b ), patients with spinal cord injury (Venturelli et al, 2014 ), and heart failure (Ives et al, 2016 ). During this evaluation, the subjects rested in the upright-seated position for 20 min before the start of data collection and remained in this position throughout this part of the study.…”

“…Relative changes (Δpeak) from rest of femoral blood flow was determined for each subject. To perform muscle volume effect-correction related to the skeletal muscle atrophy, Δpeak blood flow was normalized by thigh muscle volume (Venturelli et al, 2014 ).…”