ECSS Paris 2023: CP-PN18
INTRODUCTION: Cardiovascular disease (CVD) is one of the major causes of death in the industrialized countries[1]. CVD results from the interaction of multiple genetic, behavioral, metabolic, environmental and socio-economic risk factors, including age-related alterations in the elastic properties and integrity of arterial walls[2]. Nitric oxide (NO) plays a pivotal role in the cardiovascular system and reduced NO bioavailability has been linked to increased susceptibility to atherosclerotic lesion progression, hypertension, hypercholesterolemia, thrombosis and stroke, suggesting microvasculature can contribute to the whole CVD process[3]. The objective of this study was to examine the microvasculature integrity of older individuals with different CVD risk, whilst also investigating the modulating effects of cardiorespiratory fitness and physical activity. METHODS: Twenty-two healthy old adults (age:74±5yrs; 9 females) were recruited. CVD risk was assessed based on the American Heart Association Life’s Essential 8 algorithm[4]. Blood samples and blood pressure (BP) were collected in resting condition. Habitual physical activity was monitored by accelerometry for 7 days. An incremental cycling test up to exhaustion was performed to measure peak oxygen uptake (VO2peak). Microvasculature integrity was assessed by doppler-ultrasound on femoral artery during passive-leg movement (PLM) and by near-infrared spectroscopy (NIRS) on the vastus lateralis muscle during vascular occlusion test (VOT). Hyperemic response from PLM was quantified analyzing blood flow parameters as area under curve (AUC) and changes from baseline to maximal hyperemia (ΔPeak). The 10s change in tissue saturation index during the reperfusion rate from prolonged ischemia (Slope2) was used as index of microvasculature responsiveness. RESULTS: Among all subjects 25% were smokers, 72% did not meet the recommendation to eat five fruits and vegetables per day, and 40.8% had a high level of sedentary behavior. Blood-related parameters and BP confirmed differences in CVD risk among the old individuals. VO2peak ranged from 15.4 to 45.3ml/min/kg. Average AUC and ΔPeak values were 175±95ml and 436±115ml/min, respectively. Slope2 ranged from 0.98 to 2.75%/s. PLM and VOT parameters were directly correlated with CVD risk (r=0.45 and r=0.42, respectively; all p<0.05) and VO2peak (r=0.59 and r=0.47 respectively; all p<0.05). Adjusted for VO2peak and sedentary time, CVD risk still correlated to indexes of microvasculature responsiveness. CONCLUSION: In addition to clinical parameters classically used to estimate CVD risk, microvascular dysfunction assessed by passive-leg movement and NIRS correlates to higher CVD risk. Individual aerobic fitness correlated to indexes of microvasculature responsiveness, suggesting that during aging an active lifestyle can reduce CVD risk also through changes in small vessels. REFERENCES [1] Nassem, Mol Aspects Med 2004 [2] Yusuf, Lancet 2020 [3] Napoli, Arch Farm Res 2009 [4] Lloyd-Jones, J Am Coll Cardiol 2022
Read CV Letizia GiustiECSS Paris 2023: CP-PN18
INTRODUCTION: Physical exercise increases shear stress in the vasculature leading to better vasodilator and constrictor responsiveness, reducing arterial stiffness and oxidative stress. Acute hemodynamic adaptations to exercise lead to changes in both endothelial and vascular smooth muscle cell functions. Regular exercise training improves nitric oxide (NO) availability. We propose a method for evaluating the muscular tissue’s vessel stiffness, endothelial and vasomotor function, based on the oscillations of the hemodynamic parameters measured by fast Time Domain (TD) near infrared spectroscopy (NIRS). METHODS: A fast TD NIRS [1] acquisition on a healthy subject was performed employing a device previously developed at the Department of Physics, at Politecnico di Milano [2]. The tibialis anterior muscle was chosen due to its thin adipose tissue thickness (ATT), which allows to analyze data using the solution of the photon diffusion equation for homogeneous media. A subject was set down with the ankle fixed onto a holder and connected to a load cell for measuring the traction force exerted. He performed a 400 s long dorsiflexion, which was preceded and followed by 400 s of baseline and recovery, respectively. The protocol was chosen based on numerical simulations previously performed. The acquisition lasted 1200 seconds with an acquisition rate of 20 Hz and a 4 cm interfiber distance. The time course of the exerted force from the dynamometer was obtained to control the exercise execution. Absolute values for the time courses of oxy- (O2Hb) and deoxy- (HHb) hemoglobin concentrations were obtained. A blood volume pulse (BVP) sensor located on the same muscle and a respiration band (RESP) were also employed to record physiological signals. After a 3rd order polynomial detrending, the power spectral density (PSD) was calculated for all the parameters. The mean power in six frequency bands related to peculiar physiological origin was derived [3]: Endothelial (VI), NO-related Endothelial (V), Neurogenic (IV), Myogenic (III), Respiratory (II) and Cardiac (I) activity. RESULTS: During rest, most of the PSD power for the TD NIRS parameters is contained in the endothelial bands, in particular in band VI for HHb and band VI and V for O2Hb. The PSD of BVP is similar to the one of O2Hb and HHb, while a strong contribution to band II is found for RESP, as expected. During the contraction and the recovery, it is possible to notice clear differences in the power measured in bands VI, V and III for both hemoglobin, while in band II and I the changes are negligible. CONCLUSION: In this pilot study we have verified the possibility to employ fast TD NIRS to underline skeletal muscle vascular functions during contraction and recovery, for what concern the endothelial and myogenic activity. We are acquiring more subjects (up to 20) to perform statistical analysis. Reference: [1] Torricelli et al., Neuroimage 85, 2014. [2] Re et al., Sensors 23, 2023. [3] Kvernmo et al., Microvascular Research 56, 1998.
Read CV Rebecca ReECSS Paris 2023: CP-PN18
INTRODUCTION: 4.4 million people are living with diabetes in the UK, which can be associated with serious health complications including 184 lower-limb amputations per week. This typically stems from the development of diabetic foot, resulting in a loss of a vascularisation from damage to nerves and blood vessels. Diabetic foot is associated with a 25% chance of developing a diabetic foot ulcer within their lifetime for people with diabetes, with a 40% risk of reoccurrence within 1-year and long-term impacts on healthcare services. Therefore, this study aimed to apply a 4-week ischaemic preconditioning (IPC) intervention to assess the health of the foot in people with diabetes. IPC involves the application of repeated cycles of alternating occlusion and reperfusion, typically prior to exercise, which may improve the microcirculation and endothelial function. METHODS: With institutional ethical approval, 14 participants volunteered (8 males, 6 females; 9 type 1 diabetes, 5 type 2 diabetes; age: 39.9 ± 24.1 years; height: 171.4 ± 6.5 cm; body mass: 80.6 ± 15.1 kg). Participants visited for a pre- and post-testing session involving an incremental step test performing 30 repetitions of isotonic plantar flexion and dorsiflexion at an increasing resistance on the isokinetic dynamometer. Participants were randomly assigned to one of two groups: IPC or SHAM. The training sessions involved 2 sessions per week for 4-weeks with three occlusion cycles of 5-minutes at an individualised arterial occlusion pressure (Mean ± SD: 190 ± 30 mmHg) for the IPC groups and 20 mmHg for the SHAM group. The health of the foot was assessed during every session using near-infrared spectroscopy to assess the oxygen saturation (SO2), oxygenated (O2Hb) and deoxygenated haemoglobin (HHb) in the abductor hallucis muscle. RESULTS: There was a significant effect of time on SO2max (F(1,12) = 13.261, p = 0.003), with post-hoc analysis showing a significant increase in SO2max from 67.84 ± 6.19% to 72.86 ± 6.74% in the IPC group at post-testing (F(1,6) = 11.539, p = 0.015). There were no significant differences in peak oxygen uptake (p = 0.085), O2Hbmax (p = 0.513), HHbmax (p = 0.348) or maximum torque (p = 0.077). The average O2Hb showed a significant interaction effect between time and group at each workload increment (p < .05). CONCLUSION: The aim of this intervention was to assess whether 4-weeks of IPC resulted in any improvement in NIRS-derived variables as an indicator of the health of the foot in people with diabetes. The results showed a significant increase in SO2max evidencing an improvement in the oxygenation of the foot, which could have important health benefits in potentially limiting complications. This study is one of the first known to apply a repeated IPC intervention with an ankle occlusion, which offers an isolated foot intervention which could be an alternative for people living with diabetic foot who are unable to exercise or weight-bear.
Read CV Chloe FrenchECSS Paris 2023: CP-PN18