Heterogeneity in the vasodilatory function of individual extremities

The effect of self-identified arm dominance on exercising forearm hemodynamics and skeletal muscle desaturation

The human forearm model is commonly employed in physiological investigations exploring local vascular function and oxygen delivery; however, the effect of arm dominance on exercising forearm hemodynamics and skeletal muscle oxygen saturation (SmO2) in untrained individuals is poorly understood. Therefore, the purpose of this study was to explore the effect of self-identified arm dominance on forearm hemodynamics and SmO2 in untrained individuals during submaximal, non-ischemic forearm exercise. Twenty healthy individuals (23±4 years, 50% female; 80% right-handed) completed three-minute bouts of supine rhythmic (1 second contraction: 2 second relaxation duty cycle) forearm handgrip exercise at both absolute (10kg; 98N) and relative (30% of maximal voluntary contraction) intensities in each forearm. Beat-by-beat measures of forearm blood flow (FBF; ml/min), mean arterial blood pressure (MAP; mmHg) and flexor digitorum superficialis SmO2 (%) were obtained throughout and averaged during the final 30 seconds of rest, exercise, and recovery while forearm vascular conductance was calculated (FVC; ml/min/100mmHg). Data are Δ from rest (mean±SD). Absolute force production did not differ between non-dominant and dominant arms (97±11 vs. 98±13 N, p = 0.606) whereas relative force production in females did (69±24 vs. 82±25 N, p = 0.001). At both exercise intensities, FBFRELAX, FVCRELAX, MAPRELAX, and the time constant tau for FBF and SmO2 were unaffected by arm dominance (all p>0.05). While arm dominance did not influence SmO2 during absolute intensity exercise (p = 0.506), the non-dominant arm in females experienced an attenuated reduction in SmO2 during relative intensity exercise (-14±10 vs. -19±8%, p = 0.026)-though exercise intensity was also reduced (p = 0.001). The present investigation has demonstrated that arm dominance in untrained individuals does not impact forearm hemodynamics or SmO2 during handgrip exercise.

Effect of Hand Dominance on Radial Artery Spasm and Occlusion: A Prospective Observational Study

Transradial access has become the most commonly used method for cardiac catheterization. Many medical and technical applications have been proposed to reduce TRA complications. The aim of this study is to examine the effect of hand dominance on radial artery spasm and radial artery occlusionin subjects undergoing CC via TRA. Between April 2020 and August 2022, 1713 subjects who underwent CC via TRA were included in the study. Patient data were obtained in terms of hand dominance of the catheterized side and RAS and RAO during a 1-month follow-up period. RAS was seen in 9.6% of the subjects. The RAS in patients catheterized by the dominant hand was significantly higher than that performed by the non-dominant hand (12 vs 7.8%; P = .004). RAO was seen in 1% of the subjects. RAO was significantly higher in the spasm side than in the no-spasm side (3 vs .8%; P = .009). Hand dominance was determined as an independent predictor of radial artery spasm (P = .006). In our study, RAS and RAO were more common on the dominant hand side than on the non-dominant side. Choosing the non-dominant hand for TRA for CC may reduce the incidence of RAS and RAO.

Evidence of increased cardiovascular disease risk in left-handed individuals

Background

Approximately 10% of the world is left-handed (LH). Research suggests that LH individuals may have shorter lifespans compared to right-handed (RH) individuals. LH individuals also appear to have more cardiovascular disease (CVD) related conditions like diabetes and cancer. Thus, the present study sought to test the hypothesis that vascular function and heart rate variability (HRV), both key indicators of CVD risk, would be lower in LH compared to RH individuals.

Methods

Three hundred seventy-nine participants, 18-50 years old, were enrolled. Flow-mediated dilation (FMD), a bioassay of vascular endothelial function and standard deviation of R-R interval (SDNN), a parameter of HRV, were evaluated as indices of CVD risk. Data are reported as mean ± SD.

Results

12.1% of the participants were LH. No differences in demographics or clinical laboratory values were observed between groups, except high-density lipoprotein (HDL) was higher (p = 0.033) in RH. FMD was significantly (p = 0.043) lower in LH (6.1% ± 3.2%) compared to RH (7.6% ± 3.8%), independent of age, sex, race, BMI, and HDL. Total power (p = 0.024) and low-frequency power (p = 0.003) were lower in LH compared to RH. Additionally, SDNN was lower (p = 0.041) in LH (47.4 ± 18.8 ms) compared to RH (54.7 ± 22.3 ms). A negative correlation between FMD and mean arterial pressure (r = -0.517; p < 0.001) was observed in LH; no relationships were observed in RH (all p > 0.05).

Conclusion

Vascular endothelial function and HRV are lower in LH compared to RH. In addition, relationships between FMD and traditional CVD risk factors were only observed in LH. These data support an increased risk of CVD in LH.

Does leg dominance influence anterolateral thigh flap perforators?

INTRODUCTION

Thorough knowledge of perforator anatomy can facilitate anterolateral thigh (ALT) free flap harvest. The selection of the right or left thigh as donor area may be supported by preoperative perforator imaging and practical considerations. The study aims to determine if the leg dominance should be taken into account, when choosing the donor thigh for ALT free flap harvest, as muscle mass and perfusion might influence perforator quantity.

METHODS

ALT perforators were localized by color-coded duplex sonography and dynamic infrared thermography on both thighs within a defined 250 × 80 mm area in 24 subjects. Perforator number and thickness of subcutaneous tissue and muscle layer were compared in dominant and nondominant legs.

RESULTS

We found no statistically significant difference comparing sonographically identified ALT perforator numbers and hot spot numbers in dominant and nondominant legs. Yet, we found high interindividual differences. The comparison of subcutaneous tissue and muscle thickness yielded no significant difference.

CONCLUSIONS

Our study yielded no evidence for preference of the dominant or nondominant leg in ALT free flap harvesting. As we found high interindividual differences in perforator number, we suggest to rely on preoperative perforator imaging when choosing the ALT free flap donor thigh.

Perfusion, Stance and Plantar Pressure Asymmetries on the Human Foot in the Absence of Disease—A Pilot Study

Physiological perfusion asymmetries in the lower limb are known, although poorly understood, as are asymmetries reported in plantar pressure and stance. This preliminary study aims to explore potential relationships between perfusion and pressure variables in humans. A convenience sample of eight healthy individuals (25.25 ± 5.37 years old) of both sexes, was selected. Chosen variables were perfusion, plantar pressure, and stance. Perfusion was measured in both feet by laser Doppler flowmetry (LDF) and polarized light spectroscopy (PSp), and plantar pressure and stance obtained by a pressure plate. These were measured in baseline (Phase I) in a repeated squatting (Phase II), and in recovery (Phase III). A 95% confidence interval was adopted. Intraindividual significant perfusion asymmetries between both feet were detected by LDF in Phase I. These disappeared in Phase II and returned in Phase III. PSp did not detect any asymmetries. Plantar pressure was also asymmetric and differently distributed along both feet with no statistical significance except in the hindfoot. Significant correlations were found between BMI and mean Plantar Pressure in Phase I and Phase III, and an inverse correlation between LDF perfusion and Plantar Pressure in Phase I. These results seem to suggest an interesting direction for exploration and study of these asymmetries in the absence of disease.

Lower Limb Perfusion Asymmetries in Humans at Rest and Following Activity—A Collective View

The significance of lower limb perfusion asymmetries remains unknown in healthy individuals. Our study aims to understand how factors such as posture, sex, age, and body weight relate to perfusion. Data from studies previously published by our group, including experiments using laser Doppler flowmetry as the gold standard for perfusion measurements in baseline, (various) challenge, and recovery phases was assembled from a total of 139 healthy participants. Body position was shown to be a primary determinant of perfusion asymmetry, especially in women. Effects of sex and age were also analyzed. In a supine position, perfusion asymmetries seemed to relate negatively in the aged group of participants, where challenge and recovery seemed to follow different processes. In the upright position, young men and women have shown comparable distributions and asymmetry ratios at baseline and recovery. In the aged group, differences between sexes were observed at baseline, but again, the course of the asymmetry ratios with challenge was essentially similar in men and women. Our analysis suggests that ageing is a critical determinant in our upright study sample, as higher baseline asymmetries and longer recoveries after challenge were linked in older males with higher body mass index (BMI).

Effects of Dominant and Nondominant Limb Immobilization on Muscle Activation and Physical Demand during Ambulation with Axillary Crutches

The purpose of this study was to investigate the effects of how limb dominance and joint immobilization alter markers of physical demand and muscle activation during ambulation with axillary crutches. In a crossover, counterbalanced study design, physically active females completed ambulation trials with three conditions: (1) bipedal walking (BW), (2) axillary crutch ambulation with their dominant limb (DOM), and (3) axillary crutch ambulation with their nondominant limb (NDOM). During the axillary crutch ambulation conditions, the non-weight-bearing knee joint was immobilized at a 30-degree flexion angle with a postoperative knee stabilizer. For each trial/condition, participants ambulated at 0.6, 0.8, and 1.0 mph for five minutes at each speed. Heart rate (HR) and rate of perceived exertion (RPE) were monitored throughout. Surface electromyography (sEMG) was used to record muscle activation of the medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) unilaterally on the weight-bearing limb. Biceps brachii (BB) and triceps brachii (TB) sEMG were measured bilaterally. sEMG signals for each immobilization condition were normalized to corresponding values for BW.HR (p < 0.001) and RPE (p < 0.001) were significantly higher for both the DOM and NDOM conditions compared to BW but no differences existed between the DOM and NDOM conditions (p > 0.05). No differences in lower limb muscle activation were noted for any muscles between the DOM and NDOM conditions (p > 0.05). Regardless of condition, BB activation ipsilateral to the ambulating limb was significantly lower during 0.6 mph (p = 0.005) and 0.8 mph (p = 0.016) compared to the same speeds for BB on the contralateral side. Contralateral TB activation was significantly higher during 0.6 mph compared to 0.8 mph (p = 0.009) and 1.0 mph (p = 0.029) irrespective of condition. In conclusion, limb dominance appears to not alter lower limb muscle activation and walking intensity while using axillary crutches. However, upper limb muscle activation was asymmetrical during axillary crutch use and largely dependent on speed. These results suggest that functional asymmetry may exist in upper limbs but not lower limbs during assistive device supported ambulation.