Sex differences in calf muscle hemoglobin oxygen saturation in patients with intermittent claudication

Peripheral arterial disease in women

Peripheral arterial disease (PAD) represents one of the most frequent manifestations of atherosclerosis in men and women. In both sexes, PAD is related to classical risk factors of atherosclerosis, which are similarly distributed, but some additional factors determine differences between men and women. More frequent asymptomatic disease in women than in men and less frequent screening in women may result in a false underestimation of the prevalence of PAD in women. All these factors may cause delayed diagnosis and treatment of PAD in women. Estrogen hormones have vasoprotective properties that lower the prevalence of atherosclerosis in women of younger age. However, estrogen probably does not have a protective role against the development of cardiovascular disease in women of an older age. Hormone replacement therapy (HRT) of less than one year does not appear to reduce the odds of developing PAD in postmenopausal women. It may even increase the risk of morbidity from vascular interventions. However, some studies indicated that HRT for more than one year significantly decreases the risk of PAD if administered early after the last menstruation. Also, treatment of PAD in women differs to some extent from men.

Disparities in Diagnosis, Treatment, and Outcomes of Peripheral Artery Disease: JACC Scientific Statement

Disparities by sex, race, socioeconomic status, and geography exist in diagnosis, treatment, and outcomes for people with lower extremity peripheral artery disease (PAD). PAD prevalence is similar in men and women, but women have more atypical symptoms and undergo lower extremity revascularization at older ages compared to men. People who are Black have an approximately 2-fold higher prevalence of PAD, compared to people who are White and have more atypical symptoms, greater mobility loss, less optimal medical care, and higher amputation rates. Although fewer data are available for other races, people with PAD who are Hispanic have higher amputation rates than White people. Rates of amputation also vary by geography in the United States, with the highest rates of amputation in the southeastern United States. To improve PAD outcomes, intentional actions to eliminate disparities are necessary, including clinician education, patient education with culturally appropriate messaging, improved access to high-quality health care, science focused on disparity elimination, and health policy changes.

Maximal calf conductance is associated with 6-minute walk distance in participants with and without peripheral artery disease

INTRODUCTION

The aims were (a) to compare the maximal calf conductance and 6-minute walk distance of participants with and without peripheral artery disease (PAD) and claudication, (b) to determine whether maximal calf conductance was more strongly associated with 6-minute walk distance in participants with PAD than in the controls, and (c) to determine whether this association was significant in participants with PAD after adjusting for ABI, as well as for demographic, anthropometric, and comorbid variables.

METHODS

Participants with PAD (n = 633) and without PAD (n = 327) were assessed on maximal calf conductance using venous occlusion plethysmography, and on 6-minute walk distance. Participants were further characterized on ABI, and on demographic, anthropometric, and comorbid variables.

RESULTS

The PAD group had lower maximal calf conductance than the control group (0.136 ± 0.071 vs 0.201 ± 0.113 mL/100 mL/min/mmHg, p < 0.001). Additionally, the PAD group had a lower 6-minute walk distance (375 ± 98 m vs 480 ± 107 m, p < 0.001). Maximal calf conductance was positively associated with 6-minute walk distance in both groups (p < 0.001) and was more strongly associated in the PAD group (p < 0.001). In adjusted analyses, maximal calf conductance remained positively associated with 6-minute walk distance in the PAD group (p < 0.001) and in the control group (p < 0.001).

CONCLUSIONS

Participants with PAD and claudication had impaired maximal calf conductance and a lower 6-minute walk distance than those without PAD, and maximal calf conductance was positively and independently associated with 6-minute walk distance within each group before and after adjusting for ABI, and for demographic, anthropometric, and comorbid variables.

Microvascular dysfunction and neurovascular uncoupling are exacerbated in peripheral artery disease, increasing the risk of cognitive decline in older adults

Peripheral artery disease (PAD) is a vascular pathology with high prevalence among the aging population. PAD is associated with decreased cognitive performance, but the underlying mechanisms remain obscure. Normal brain function critically depends on an adequate adjustment of cerebral blood supply to match the needs of active brain regions via neurovascular coupling (NVC). NVC responses depend on healthy microvascular endothelial function. PAD is associated with significant endothelial dysfunction in peripheral arteries, but its effect on NVC responses has not been investigated. This study was designed to test the hypothesis that NVC and peripheral microvascular endothelial function are impaired in PAD. We enrolled 11 symptomatic patients with PAD and 11 age- and sex-matched controls. Participants were evaluated for cognitive performance using the Cambridge Neuropsychological Test Automated Battery and functional near-infrared spectroscopy to assess NVC responses during the cognitive n-back task. Peripheral microvascular endothelial function was evaluated using laser speckle contrast imaging. We found that cognitive performance was compromised in patients with PAD, evidenced by reduced visual memory, short-term memory, and sustained attention. We found that NVC responses and peripheral microvascular endothelial function were significantly impaired in patients with PAD. A positive correlation was observed between microvascular endothelial function, NVC responses, and cognitive performance in the study participants. Our findings support the concept that microvascular endothelial dysfunction and neurovascular uncoupling contribute to the genesis of cognitive impairment in older PAD patients with claudication. Longitudinal studies are warranted to test whether the targeted improvement of NVC responses can prevent or delay the onset of PAD-associated cognitive decline.NEW & NOTEWORTHY Peripheral artery disease (PAD) was associated with significantly decreased cognitive performance, impaired neurovascular coupling (NVC) responses in the prefrontal cortex (PFC), left and right dorsolateral prefrontal cortices (LDLPFC and RDLPFC), and impaired peripheral microvascular endothelial function. A positive correlation between microvascular endothelial function, NVC responses, and cognitive performance may suggest that PAD-related cognitive decrement is mechanistically linked, at least in part, to generalized microvascular endothelial dysfunction and subsequent impairment of NVC responses.

Aging alters gastrocnemius muscle hemoglobin oxygen saturation (StO2) characteristics in healthy individuals

PURPOSE

Functional limitations during exercise from alterations in the balance of oxygen supply and demand-as reported by lower tissue oxygen saturation and longer recovery time-are well documented in clinical populations. We aimed to assess changes in skeletal muscle hemoglobin oxygen saturation (StO₂) characteristics during exercise as a result of aging in otherwise healthy individuals.

METHODS

We recruited healthy male and female participants (n = 101) from three age ranges-young (18-39 years), middle age (40-65 years), and older (> 65 years)-to complete exercise tests commonly used in clinical populations. Using near-infrared spectroscopy (NIRS) we assessed StO₂ in the medial gastrocnemius during the Gardner Treadmill Protocol and 6 min walk test (6MWT).

RESULTS

Minimum StO₂ (%) during the treadmill test was significantly lower for both middle-age (36.1 ± 20.6) and older (27.3 ± 19.4) participants compared to young (46.8 ± 14.8) (p < 0.05 and p < 0.01 respectively), and recovery time (minutes) was significantly prolonged (young = 0.22 ± 0.34; middle age = 0.66 ± 0.52; older = 1.04 ± 1.00) (p < 0.001 for both middle age and older compared to young). Similar results were shown during the 6MWT, as minimum StO₂ (%) was lower in middle-age (41.7 ± 17.2) and older (40.0 ± 25.9) participants compared to young (53.6 ± 14.5) (p < 0.05), and recovery times (minutes) were prolonged (young: 0.11 ± 0.17; middle age: 0.46 ± 0.42; older: 0.93 ± 0.43) (p < 0.001 for both middle age and older compared to young). Simple linear regression analyses demonstrated that age predicted treadmill recovery and 6MWT recovery.

CONCLUSION

Our study provides evidence that aging, even in otherwise healthy individuals, negatively impacts muscle StO₂ characteristics. In older individuals, working muscle tissue may reach lower oxygen saturation during exercise and take longer to return to baseline oxygen saturation post-exercise.

Association Between Daily Steps at Moderate Cadence and Vascular Outcomes in Patients With Claudication

PURPOSE

We determined whether patients with peripheral artery disease (PAD) and claudication grouped according to tertiles of community-based daily steps taken at a moderate cadence had differences in vascular function and biomarkers and whether group differences in vascular function and biomarkers persisted after adjusting for demographic variables, comorbid conditions, and severity of PAD.

METHODS

Two hundred sixty-three patients were evaluated for 1 wk on steps taken at a moderate cadence (exceeding 60 steps/min), and patients were placed into low (group 1), intermediate (group 2), and high (group 3) tertiles.

RESULTS

Ankle/brachial index (ABI) at 1 min after exercise (mean ± SD) was significantly higher in groups 2 and 3 than in group 1 in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1: 0.34 ± 0.25; group 2: 0.38 ± 0.27; and group 3: 0.44 ± 0.28). Exercise time to reach the minimum calf muscle oxygen saturation (StO2) value during treadmill exercise was significantly longer in groups 2 and 3 than in group 1 in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1: 127 ± 127 sec; group 2: 251 ± 266 sec; and group 3: 310 ± 323 sec). Fibrinogen was significantly lower in group 3 than in group 1 in unadjusted (P = .02) and adjusted (P = .05) analyses (group 1: 3.5 ± 1.2 g/L; group 2: 3.6 ± 1.5 g/L; and group 3: 3.0 ± 1.1 g/L).

CONCLUSIONS

Compared with patients with claudication in the lowest tertile of community-based daily steps taken at a moderate cadence, patients in the second and third tertiles had better calf muscle StO2 and ABI values during and immediately after exercise. Second, the most active group had lower fibrinogen levels than the least active group.

Cognitive decrement in older adults with symptomatic peripheral artery disease

Peripheral artery disease (PAD) is highly prevalent, affecting up to 20% of people over 70 years of age. To test the hypothesis that PAD promotes the pathogenesis of vascular cognitive impairment (VCI), we compared cognitive function in older adults with symptomatic PAD and in participants without PAD who had a burden of comorbid conditions. Furthermore, we compared the cognitive function of these groups after adjusting for demographic and clinical characteristics, comorbid conditions, and cardiovascular risk factors. Participants with PAD (age: 69 ± 8 years; n = 58) and those without PAD (age: 62 ± 8 years; n = 30) were assessed on a battery of eight neuropsychological tests. The tests assessed attention and working memory, verbal memory, non-verbal memory, perceptuo-motor speed, and executive function. Participants were further characterized on demographic and clinical characteristics, comorbid conditions, cardiovascular risk factors, and ankle-brachial index. The PAD group had significantly lower neuropsychological scores than the non-PAD control group on all eight tests (P < .01). After adjusting for covariates, significantly worse scores in the PAD group persisted for verbal memory, measured by tests on logical memory-immediate recall (P = .022), and logical memory-delayed recall (P < .001), and for attention and working memory, measured by tests on digits forward (P < .001), and digits backward (P = .003). Participants with symptomatic PAD have substantially lower levels of performance on tests of attention, working memory, and verbal memory than participants without PAD independent of demographic characteristics and comorbid health burdens. These findings provide additional evidence in support of the concept that generalized accelerated vascular aging manifesting as symptomatic PAD in the peripheral circulation also affects the brain promoting the pathogenesis of VCI. These cognitive difficulties may also negatively impact symptomatic patient's ability to understand and adhere to behavioral and medical therapies, creating a vicious cycle. We speculate that more intensive follow-up may be needed to promote adherence to therapies and monitor cognitive decline that may affect care.

Effect of Sex on Vascular Adaptations to Isometric Handgrip Training in Elderly Patients with Peripheral Artery Disease: A Randomized Controlled Trial

BACKGROUND

Isometric handgrip training (IHT) promotes vascular adaptations in different populations.

AIMS

We assessed the sex differences in vascular adaptations of IHT in a sample of older adults with symptomatic peripheral artery disease (PAD).

METHODS

Fifty-three older patients with symptomatic PAD (6 women and 13 men in IHT and 13 women and 21 men in the control group) participated in this study. The IHT group performed 3 sessions per week, for 8 weeks, consisting of 4 sets of isometric contractions for 2 min at 30% of maximum voluntary contraction and a 4-min interval between sets. The control group received a compression ball in order to minimize the placebo effects, representing sham training. Blood flow and brachial flow-mediated dilation were analyzed at before and after 8 weeks of intervention. We compared the responses (Δ = post-pre values) of each group (women control, women IHT, men control, and men IHT) with a Kruskal-Wallis test.

RESULTS

There were no differences in all groups after 8 weeks of IHT in Δ brachial diameter (p = 0.850), Δ flow-mediated dilation (p = 0.241), Δ time to peak diameter (p = 0.528), and Δ FMD/AUC (p = 0.397).

CONCLUSIONS

There are no effects of sex on vascular adaptation after 8 weeks of IHT in older adults with symptomatic PAD.

Calf and non-calf hemodynamic recovery in patients with arterial claudication: Implication for exercise training

BACKGROUND

Previous studies in patients with arterial claudication have focused on calf hemodynamic recovery. We hypothesized that the duration of hemodynamic recovery with TcpO2 at calf and non-calf levels would be shorter than 10 min. We analyzed the factors that influence the recovery time.

METHODS

We monitored limb changes minus chest changes from rest (DROP) of transcutaneous oximetry on buttocks, thighs and calves, during and following a treadmill test (3.2 km/h; 10% grade). We calculated the time required to reach 50% (50%RT) and 10% (90%RT) of minimal DROP value (DROPm) from walking cessation. Regression analyses were used to determine the factors associated to 50%RT and 90%RT.

RESULTS

Of the 132 patients studied, 18.2% reported isolated non-calf pain by history. Of the 792 recovery time values, only 3 (0.4%) and 23 (2.9%) were in excess of 10 min for 50%RT and for 90%RT, respectively. A weak correlation was found between each of the 792 DROPm and 50%RT (r = -0.270, p < 0.001) as well as for 90%RT (r = -0.311 p < 0.001). Lowest DROPm and BMI (but not age, sex, the use of beta-blockers, the duration of the walking period) were associated to both 50%RT and 90%RT.

CONCLUSION

Although recovery duration correlates significantly with the severity of ischemia of the same location, a wide discrepancy exists and the longest recovery time does not always correlate to the localization of the most severe ischemia. Non-calf ischemia should be measured when one aims at objectifying the biological effects of exercise or the effects of treatments on recovery from exercise.

Cardiovascular Responses during and after Maximal Walking in Men and Women with Symptomatic Peripheral Artery Disease

BACKGROUND

Walking is recommended for patients with peripheral arterial disease (PAD). It has been shown that patients with PAD present sharper increases in blood pressure (BP) and heart rate (HR) during maximal walking when compared with healthy subjects. Additionally, women with PAD present a worse physiological profile, and it is possible that they may present higher cardiovascular load during and after a bout of maximal walking than men. Thus, the objective of this study was to compare cardiovascular and autonomic responses during and after maximal walking between men and women with PAD and intermittent claudication (IC).

METHODS

Forty patients with PAD and IC (20 men and 20 women) underwent, in random order, 2 sessions: control (standing on treadmill) and exercise (maximal treadmill walking test with Gardner's protocol). During the exercise, HR and BP were measured. Before and after the sessions, cardiovascular variables (BP HR, cardiac output, peripheral vascular resistance, and stroke volume) and autonomic modulation (HR and BP variabilities and baroreflex sensitivity) were assessed. In addition, an ambulatory BP monitoring was recorded after each session.

RESULTS

Men and women presented similar maximal walking capacity. During the walking test, HR and systolic BP increased similarly in men and women. After the maximal walking, cardiovascular and autonomic responses did not differ between the genders. In addition, postintervention ambulatory BP parameters were also similar in men and women. Therefore, in men and women, maximal walking similarly reduced clinic systolic BP and stroke volume, and increased HR and total power of HR variability during the recovery period.

CONCLUSIONS

Men and women with PAD and IC present similar cardiovascular and autonomic responses during and after maximal walking.

Association between calf muscle oxygen saturation with ambulatory function and quality of life in symptomatic patients with peripheral artery disease

OBJECTIVE

The objective of this study was to determine whether calf muscle hemoglobin oxygen saturation (Sto₂) obtained during a standardized treadmill test is associated with ambulatory function and health-related quality of life (HRQoL) in patients with symptomatic peripheral artery disease (PAD). We hypothesized that a rapid decline in calf muscle Sto₂ during walking is associated with impaired ambulatory function and HRQoL and that these associations are independent of ankle-brachial index (ABI).

METHODS

Calf muscle Sto₂, peak walking time, and claudication onset time were obtained during a treadmill test in 151 symptomatic men and women with PAD. Patients were further characterized by demographic variables, comorbid conditions, cardiovascular risk factors, ABI, 6-minute walk distance, daily ambulatory activity, Walking Impairment Questionnaire (WIQ) score, and Medical Outcomes Study 36-Item Short Form Health Survey physical function score to assess HRQoL.

RESULTS

The median calf muscle Sto₂ value at rest was 52%, which declined to 22% after only 1 minute of walking during the treadmill test and reached a minimum value of 9% after a median time of 87 seconds of walking. Of the various calf muscle Sto₂ measurements obtained during the treadmill test, the exercise time to the minimum calf muscle Sto₂ value (log transformed) had the strongest univariate associations with peak walking time (r = 0.56; P < .001), claudication onset time (r = 0.49; P < .001), 6-minute walk distance (r = 0.31; P < .001), WIQ distance score (r = 0.33; P < .001), WIQ speed score (r = 0.39; P < .001), WIQ stair-climbing score (r = 0.37; P < .001), and Medical Outcomes Study 36-Item Short Form Health Survey physical function score (r = 0.32; P < .001). In adjusted multiple regression models, these associations persisted (P < .001) after adjustment for demographic measures, cardiovascular risk factors, comorbid conditions, and ABI.

CONCLUSIONS

More rapid decline in oxygen saturation of the calf musculature during walking, indicative of impaired microcirculation, is predictive of impaired ambulatory function and HRQoL in patients with symptomatic PAD. Of particular importance, these associations are independent of ABI and other common health burdens, highlighting the clinical relevance that the microcirculation has on ambulatory function and HRQoL in patients with symptomatic PAD.

Peripheral Arterial Disease in Women: an Overview of Risk Factor Profile, Clinical Features, and Outcomes

Purpose of Review

Peripheral arterial disease (PAD) is the third most common manifestation of cardiovascular disease (CVD), following coronary artery disease (CAD) and stroke. PAD remains underdiagnosed and under-treated in women.

Recent Findings

Women with PAD experience more atypical symptoms and poorer overall health status. The prevalence of PAD in women increases with age, such that more women than men have PAD after the age of 40 years. There is under-representation of PAD patients in clinical trials in general and women in particular. In this article, we address the lack of women participants in PAD trials. We then present a comprehensive overview of the epidemiology/risk factor profile, clinical features, treatment, and outcomes.

Summary

PAD is prevalent in women and its global burden is on the rise despite a decline in global age-standardized death rate from CVD. The importance of this issue has been underlined by the American Heart Association’s (AHA) “Call to Action” scientific statement on PAD in women. Large-scale campaigns are needed to increase awareness among physicians and the general public. Furthermore, effective treatment strategies must be implemented.

The Relationship Between Peripheral Artery Disease Symptomatology and Ischemia

BACKGROUND

Fewer than half of individuals with peripheral artery disease (PAD) experience classic claudication, and the relationships between PAD typical or atypical symptom intensity, location, and description (classic or atypical) with ischemic changes have not previously been reported.

OBJECTIVE

The primary purpose of this study was to evaluate the relationship between self-reported PAD symptom intensity and calf tissue ischemia measured using the tissue saturation index (TSI) during treadmill exercise. The location and descriptors of atypical PAD symptoms in the presence of calf tissue ischemia were also identified.

METHODS

Adults with PAD with exercise-limiting ischemic symptoms were asked to (a) rate symptom intensity using a numerical rating scale (NRS) from 0 to 5 (0 = no pain, 1 = onset of pain, 5 = maximal pain), (b) provide symptom locations and descriptors, and (c) wear a near-infrared spectroscopy device to obtain calf TSI values during treadmill exercise. Multilevel models with TSI as the outcome variable were estimated during exercise and recovery. Covariates included were exercise time, recovery time, baseline TSI, exercise rating, recovery rating, ankle-brachial index (ABI), age, race, gender, body mass index, diabetes, neuropathy, and smoking.

RESULTS

During three successive bouts of treadmill exercise for 40 participants (80% Caucasian men; average age = 68 years, SD = 9.2), the most rapid decline in TSI occurred between the start of exercise and symptom onset (when NRS = 1). The TSI nadir was often reached prior to report of maximum discomfort (when NRS = 5), and changes in TSI were related to exercise time (p < .001), baseline TSI (p < .001), exercise ratings (p < .001), and ABI (p < .05). During recovery, TSI increased steadily for most participants as pain eased. In the recovery model, changes in TSI were associated with recovery ratings (p < .001) and ABI (p < .03). Of 120 treadmill exercise tests, 69.2% were stopped due to discomfort in the calf with classic descriptors reported only half the time (55.4%).

DISCUSSION

Exploratory analyses revealed ischemic symptoms extended beyond classic claudication locations and descriptors. Future research should evaluate changes in TSI relative to atypical locations and descriptors to improve understanding of the full range of ischemic symptoms experienced by individuals with PAD.

Blood pressure and calf muscle oxygen extraction during plantar flexion exercise in peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million people worldwide. Although PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO₂) and a higher rise in BP in PAD compared with age-matched healthy subjects, but low-intensity steady-state plantar flexion elicits similar responses between groups. In the first experiment, eight patients with PAD and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven patients with PAD and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO₂ were measured continuously using near-infrared spectroscopy (NIRS). SmO₂ is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, patients with PAD had a greater increase in mean arterial BP (18 ± 2 vs. vs. 10 ± 2 mmHg, P = 0.029) and HR (14 ± 2 vs. 6 ± 2 beats/min, P = 0.033) and a greater reduction in SmO₂ (-54 ± 10 vs. -12 ± 4%, P = 0.001). However, both groups had similar physiological responses to low-intensity, nonpainful plantar flexion exercise. These data suggest that patients with PAD have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response.NEW & NOTEWORTHY In this laboratory study, patients with peripheral artery disease performed plantar flexion exercise in the supine posture until symptoms of claudication occurred. Relative to age- and sex-matched healthy subjects we found that patients had a higher blood pressure response, a higher heart rate response, and a greater reduction in skeletal muscle oxygenation as determined by near-infrared spectroscopy. Our data suggest that muscle ischemia contributes to the augmented exercise pressor reflex in peripheral artery disease.

Predictors of Improved Walking after a Supervised Walking Exercise Program in Men and Women with Peripheral Artery Disease

We compared the changes in ambulatory outcomes between men and women with symptomatic peripheral arterial disease (PAD) following completion of a supervised, on-site, treadmill exercise program, and we determined whether exercise training variables and baseline clinical characteristics were predictive of changes in ambulatory outcomes in men and women. Twenty-three men and 25 women completed the supervised exercise program, consisting of intermittent walking to mild-to-moderate claudication pain for three months. Men and women significantly increased claudication onset time (COT) (p < 0.001 and p < 0.01, resp.) and peak walking time (PWT) (p < 0.001 for each group). However, change in PWT was less in women (54%) than in men (77%) (p < 0.05). Neither group significantly changed 6-minute walk distance (6MWD). In women, baseline COT was the only predictor for the change in COT (p = 0.007) and the change in PWT (p = 0.094). In men, baseline COT (p < 0.01) and obesity (p < 0.10) were predictors for the change in COT, and obesity was the only predictor for the change in PWT (p = 0.002). Following a supervised, on-site, treadmill exercise program, women had less improvement in PWT than men, and neither men nor women improved submaximal, overground 6MWD. Furthermore, obese men and patients with lower baseline COT were least responsive to supervised exercise. This trial is registered with ClinicalTrial.gov, unique identifier: NCT00618670.

Effect of diabetes mellitus on walking distance parameters after supervised exercise therapy for intermittent claudication: A systematic review

Some believe that certain patients with intermittent claudication may be unsuitable for supervised exercise therapy (SET), based on the presence of comorbidities and the possibly increased risks. We conducted a systematic review (MEDLINE, EMBASE and CENTRAL) to summarize evidence on the potential influence of diabetes mellitus (DM) on the response to SET. Randomized and nonrandomized studies that investigated the effect of DM on walking distance after SET in patients with IC were included. Considered outcome measures were maximal, pain-free and functional walking distance (MWD, PFWD and FWD). Three articles met the inclusion criteria ( n = 845). In one study, MWD was 111 meters (128%) longer in the non-DM group compared to the DM group after 3 months of follow-up ( p = 0.056). In a second study, the non-DM group demonstrated a significant increase in PFWD (114 meters, p ⩽ 0.05) after 3 months of follow-up, whereas there was no statistically significant increase for the DM group (54 meters). On the contrary, the largest study of this review did not demonstrate any adverse effect of DM on MWD and FWD after SET. In conclusion, the data evaluating the effects of DM on SET were inadequate to determine if DM impairs the exercise response. While trends in the data do not suggest an impairment, they are not conclusive. Practitioners should consider this limitation when making clinical decisions.

Patient Characteristics and Comorbidities Influence Walking Distances in Symptomatic Peripheral Arterial Disease: A Large One-Year Physiotherapy Cohort Study

Objectives

The aim of this study is to investigate the association between age, gender, body-mass index, smoking behavior, orthopedic comorbidity, neurologic comorbidity, cardiac comorbidity, vascular comorbidity, pulmonic comorbidity, internal comorbidity and Initial Claudication Distance during and after Supervised Exercise Therapy at 1, 3, 6 and 12 months in a large sample of patients with Intermittent Claudication.

Methods

Data was prospectively collected in standard physiotherapy care. Patients received Supervised Exercise Therapy according to the guideline Intermittent Claudication of the Royal Dutch Society for Physiotherapy. Three-level mixed linear regression analysis was carried out to analyze the association between patient characteristics, comorbidities and Initial Claudication Distance at 1, 3, 6 and 12 months.

Results

Data from 2995 patients was analyzed. Results showed that being female, advanced age and a high body-mass index were associated with lower Initial Claudication Distance at all-time points (p = 0.000). Besides, a negative association between cardiac comorbidity and Initial Claudication Distance was revealed (p = 0.011). The interaction time by age, time by body-mass index and time by vascular comorbidity were significantly associated with Initial Claudication Distance (p≤ 0.05). Per year increase in age (range: 33–93 years), the reduction in Initial Claudication Distance was 8m after 12 months of Supervised Exercise Therapy. One unit increase in body-mass index (range: 16–44 kg/m²) led to 10m less improvement in Initial Claudication Distance after 12 months and for vascular comorbidity the reduction in improvement was 85m after 12 months.

Conclusions

This study reveals that females, patients at advanced age, patients with a high body-mass index and cardiac comorbidity are more likely to show less improvement in Initial Claudication Distances (ICD) after 1, 3, 6 and 12 months of Supervised Exercise Therapy. Further research should elucidate treatment adaptations that optimize treatment outcomes for these subgroups.

Gender differences following supervised exercise therapy in patients with intermittent claudication

OBJECTIVE

Prevalence of peripheral arterial disease is equal in men and women. However, women seem to suffer more from the burden of disease. Current studies on gender-related outcomes following supervised exercise therapy (SET) for intermittent claudication (IC) yield conflicting results.

METHODS

A follow-up analysis was performed on data from the 2010 Exercise Therapy in Peripheral Arterial Disease (EXITPAD) study, a multicenter randomized controlled trial including IC patients receiving SET or a walking advice. The SET program was supervised by physiotherapists and included interval-based treadmill walking approximating maximal pain combined with activities such as cycling and rowing. Patients usually started with three 30-minute sessions a week. Training frequency was adapted during the following year on the basis of individual needs. The primary outcome was gender differences regarding the change in absolute claudication distance (ACD) after SET. ACD was defined as the number of meters that a patient had covered just before he or she was forced to stop walking because of intolerable pain. Secondary outcomes were gender differences in change of functional walking distance, quality of life, and walking (dis)ability after SET. Walking distances were obtained by standardized treadmill testing according to the Gardner-Skinner protocol. Quality of life was measured by the 36-Item Short Form Health Survey, and walking (dis)ability was determined by the Walking Impairment Questionnaire (WIQ). Measurements were performed at baseline and after 3, 6, 9, and 12 months. Only patients who met the 12-month follow-up measure were included in the analysis.

RESULTS

A total of 113 men and 56 women were available for analysis. At baseline, groups were similar in terms of clinical characteristics and ACD walking distances (men, 250 meters; women, 270 meters; P = .45). ACD improved for both sexes. However, ACD increase was significantly lower for women than for men during the first 3 months of SET (Δ 280 meters for men vs Δ 220 meters for women; P = .04). Moreover, absolute walking distance was significantly shorter for women compared with men after 1 year (565 meters vs 660 meters; P = .032). Women also reported less on several WIQ subdomains, although total WIQ score was similar (0.69 for men vs 0.61 for women; P = .592). No differences in quality of life after SET were observed.

CONCLUSIONS

Women with IC benefit less during the first 3 months of SET and have lower absolute walking distances after 12 months of follow-up compared with men. More research is needed to determine whether gender-based IC treatment strategies are required.

INFLUENCE OF DIABETES ON AMBULATION AND INFLAMMATION IN MEN AND WOMEN WITH SYMPTOMATIC PERIPHERAL ARTERY DISEASE

•

Diabetes and sex were correlated with ambulation and inflammation in patients with claudication.

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Men with diabetes have worse ambulation than men without diabetes.

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Women with diabetes have greater inflammation than women free of diabetes.

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Men and women with diabetes have evidence for high levels of angiogenic inhibition.

Objective

To determine whether diabetes and sex were factors associated with ambulatory function, endothelial cell inflammation, oxidative stress, and apoptosis, and with circulating biomarkers of inflammation and antioxidant capacity in patients with peripheral artery disease (PAD) and claudication.

Materials/Methods

Ambulatory function of 180 symptomatic men and women with PAD was assessed during a graded maximal treadmill test, 6-minute walk test, and 4-meter walk test. Patients were further characterized on endothelial effects of circulating factors present in the sera using a cell culture-based bioassay on primary human arterial endothelial cells, and on circulating inflammatory and vascular biomarkers.

Results

Men and women with diabetes had greater prevalence (p = 0.007 and p = 0.015, respectively) of coronary artery disease (CAD) than patients without diabetes. To assure that this difference did not influence planned comparisons, the data set was stratified on CAD. Diabetic men with CAD had a lower peak walking time (PWT) during the treadmill test and a slower 4-meter gait speed compared to non-diabetic men with CAD (p < 0.05). Diabetic women with CAD had a lower PWT compared to their non-diabetic counterparts (p < 0.01). Additionally, diabetic men with CAD had higher pigment epithelium-derived factor (p < 0.05) than their non-diabetic counterparts, and diabetic women with CAD had higher leptin (p < 0.01) and interleukin-8 levels (p < 0.05).

Conclusions

In patients with PAD, diabetic men and women with CAD had more severe claudication than their non-diabetic counterparts, as measured by shorter PWT, and the men had further ambulatory impairment manifested by slower 4-meter gait speed. Furthermore, the diabetic patients with CAD had elevations in interleukin-8, leptin, and PEDF.

Sex-specific predictors of improved walking with step-monitored, home-based exercise in peripheral artery disease

The aim of this study was to determine whether baseline clinical characteristics and the duration and intensity of ambulation during our step-monitored home-based exercise program were predictive of changes in ambulatory outcomes at completion of the program in symptomatic patients with peripheral artery disease (PAD). Twenty-two men (ankle-brachial index (ABI) = 0.71 ± 0.19) and 24 women (ABI = 0.66 ± 0.23) completed the home exercise program, consisting of intermittent walking to mild-to-moderate claudication pain for 3 months. Ambulatory outcome measures were peak walking time (PWT) and claudication onset time (COT) during a treadmill test, and the distance recorded during a 6-minute walk distance test (6MWD). Men experienced significant increases (p<0.01) in COT, PWT, and 6MWD following the home exercise program, and women had significant increases in 6MWD (p<0.01) and PWT (p<0.05). In women, average exercise cadence during the home exercise sessions was the only predictor that entered the model for change in COT (p=0.082), and was the first predictor in the model for change in PWT (p=0.029) and 6MWD (p=0.006). In men, the ABI was the only predictor that entered the model for change in 6MWD (p=0.002), and ABI was a predictor along with metabolic syndrome in the model for change in COT (p=0.003). No variables entered the model for change in PWT. Faster ambulatory cadence during the step-monitored home-based exercise program may predict greater improvements in ambulatory function in women, whereas having less severe PAD and comorbid burden at baseline may predict greater improvements in ambulatory function in men. ClinicalTrials.gov Identifier: NCT00618670.

Clinical Interest of Ambulatory Assessment of Physical Activity and Walking Capacity in Peripheral Artery Disease

The purpose of the present review was to provide, for the first time, a comprehensive analysis and synthesis of the available studies that highlighted the clinical interest of the ambulatory assessment of either physical activity (PA) or walking capacity in patients with lower extremity peripheral artery disease (PAD). We identified 96 related articles published up to March 2015 through a computer-assisted search of the MEDLINE, EMBASE, and Web of Science databases. Ambulatory-measured PA or related energy expenditure (EE) in PAD patients was performed in 87 of the 96 included studies. The main clinical interests of these measurements were (a) the assessment of PA/EE pattern; (b) the characterization of walking pattern; and (c) the control of training load during home-based walking programs. Ambulatory-measured walking capacity was performed in the remaining studies, using either Global Positioning System receivers or the Peripheral Arterial Disease Holter Control device. Highlighted clinical interests were (a) the assessment of community-based walking capacity; (b) the use of new outcomes to characterize walking capacity, besides the conventional absolute claudication distance; and (c) the association with the patient's self-perception of walking capacity. This review also provides for the clinicians step-by-step recommendations to specifically assess PA or walking capacity in PAD patients.

V.O2 Kinetics and clinical factors among patients with peripheral artery disease

PURPOSE

To investigate the association between oxygen uptake (V.O2) kinetics and demographic, behavioral, and clinical factors among patients with peripheral artery disease (PAD).

METHODS

A total of 85 PAD patients with intermittent claudication performed a constant load treadmill test, and breath-by-breath (V.e.)O2 was obtained to assess V.O2 kinetics. Demographic information, anthropometry, cardiovascular risk factors, and comorbid conditions were recorded.

RESULTS

Using univariate analyses, higher values of tau ([τ], i.e., slowed V.O2 kinetics) were associated with female gender, non-Caucasian race, hypertension, dyslipidemia, and age ≤66 years. Smoking, diabetes, obesity, metabolic syndrome, height, and ankle brachial index were not significantly related to V.O2 kinetics. Using multiple regression procedures, the identified predictors of slowed V.O2 kinetics were female gender (4.76 [95% CI: 1.49-8.03] seconds; P = .0049), non-Caucasian race (4.70 [95% CI: 1.29-8.12] seconds; P = .0075), hypertension (12.06 [95% CI: 8.83-15.28] seconds; P < .0001), and age ≤66 years (4.97 [95% CI: 1.95-7.99] seconds; P = .0015).

CONCLUSIONS

In PAD patients, slowed V.O2 kinetics are associated with demographic and clinical factors. The clinical significance is that female, non-Caucasian, and hypertensive PAD patients present central and/or peripheral limitations that may partially account for their walking impairment.

Gender and racial differences in endothelial oxidative stress and inflammation in patients with symptomatic peripheral artery disease

BACKGROUND

We compared (1) cellular reactive oxygen species (ROS) production, inflammation, and apoptosis of cultured endothelial cells treated with sera and (2) circulating inflammatory measures, antioxidant capacity, vascular biomarkers, and calf muscle hemoglobin oxygen saturation (StO2) in men and women with peripheral artery disease (PAD). A secondary aim was to compare exercise performance and daily ambulatory activity between men and women. We hypothesized that women would have more impaired endothelial cellular ROS, inflammation, and apoptosis than men as well as worse systemic inflammation, antioxidant capacity, vascular biomarkers, calf muscle StO2, exercise performance, and daily ambulatory activity.

METHODS

The 148 symptomatic men and women with PAD were characterized on the endothelial effects of circulating factors present in the sera by a cell culture-based bioassay on primary human arterial endothelial cells. Patients were further evaluated by circulating inflammatory and vascular biomarkers, physical examination and medical history, exercise performance, and calf muscle StO2 during exercise, and ambulatory activity was monitored during 1 week.

RESULTS

Cellular ROS production was higher in African American women than in men (P = .021), but there was no gender difference in white individuals (P = .537). Men and women were not significantly different on endothelial cell apoptosis (P = .833) and nuclear factor κB activity (P = .465). For circulating factors, additional gender differences were found when comparisons were made within each race. In African Americans, women had higher intercellular adhesion molecule 1 (P = .022) and leptin (P < .001); whereas in white individuals, women had higher matrix metallopeptidase 9 (P = .047), higher vascular cell adhesion molecule 1 (P = .047), and lower hepatocyte growth factor (P = .046). Overall, women had higher apolipoprotein CIII (P = .035), lower pain-free distance (P = .048) and total distance (P < .001) during the 6-minute walk test, shorter time for calf muscle StO2 to reach the minimum value during exercise (P = .027), and slower average cadence (P = .004) during daily ambulation.

CONCLUSIONS

African American women with symptomatic PAD have a heightened oxidative status, likely resulting in increased endothelial oxidative stress, compared with men. Furthermore, women exhibit a more pronounced proinflammatory profile of circulating biomarkers as well as more limited peripheral microcirculation, exercise performance, and ambulatory activity than men do. The clinical significance is that women with symptomatic PAD are in greater need than men of clinical intervention to improve oxidative stress, inflammation, and microcirculation, which may in turn have a favorable impact on their lower exercise performance and daily activity.

Diabetic women are poor responders to exercise rehabilitation in the treatment of claudication

BACKGROUND

It is not clear whether subgroups of patients with peripheral artery disease (PAD) and claudication respond more favorably to exercise rehabilitation than others. We determined whether sex and diabetes were factors associated with the response to exercise rehabilitation in patients with claudication.

METHODS

Eighty patients were randomized to home-based and supervised exercise programs, and 60 finished with complete exercise intervention data. Exercise consisted of intermittent walking to near maximal claudication pain for 3 months. Primary outcome measures included claudication onset time (COT) and peak walking time. Patients were partitioned into diabetic and nondiabetic groups and then further partitioned by sex to form four groups.

RESULTS

Overall, exercise adherence was high (84%), and there was no significant difference (P > .05) in the amount of exercise completed among the four groups. All groups had significant improvements (P < .05) in COT and peak walking time after exercise rehabilitation, except for diabetic women (P > .05). Only 37% of women with diabetes had an increase in COT compared with 100% of men with diabetes (P < .01), and their risk ratio for nonresponse was 9.2 (P < .0001).

CONCLUSIONS

Women with PAD and claudication, particularly those with diabetes, represent a vulnerable subgroup of patients who respond poorly to a program of exercise rehabilitation. Diabetic women with PAD and claudication may need a greater dose of exercise or another intervention separate from or in combination with exercise to elicit improvements in claudication measures that are similar to nondiabetic women and to diabetic and nondiabetic men.

Clinical significance of ankle systolic blood pressure following exercise in assessing calf muscle tissue ischemia in peripheral artery disease

Our primary objective assessed whether a decline in ankle systolic blood pressure (SBP) to less than 50 mm Hg after treadmill exercise is associated with lower extremity ischemia, as measured by calf muscle hemoglobin oxygen saturation (StO(2)). Eighty-four patients with peripheral artery disease (PAD) completed a treadmill test. Ankle SBP <50 mm Hg following exercise was observed in only 49% (group 1), whereas 51% had ankle SBP ≥50 mm Hg (group 2). No group differences were observed for the decline in calf muscle StO(2) to a minimum value (group 1: 18 ± 21%, group 2: 20 ± 20%; P = .60) and for the time to reach minimum StO(2) (group 1: 224 ± 251 seconds, group 2: 284 ± 283 seconds; P = .30). Requirement of ankle SBP to decrease below 50 mm Hg after exercise has little clinical significance for assessing ischemia in calf muscle of patients with PAD limited by intermittent claudication.

Calf muscle hemoglobin oxygen saturation in patients with peripheral artery disease who have different types of exertional leg pain

BACKGROUND

This study compared calf muscle hemoglobin oxygen saturation (Sto(2)) and exercise performance during standardized treadmill exercise in patients with peripheral artery disease (PAD) who describe different types of exertional leg pain and compared secondary outcomes consisting of daily ambulatory activity and exercise performance during a 6-minute walk test (6MWT).

METHODS

Leg pain symptoms were evaluated in 114 patients with PAD using the San Diego Claudication Questionnaire, by which atypical exertional leg pain was defined in 31, claudication in 37, and leg pain on exertion and rest in 46. Patients were evaluated on a standardized, graded treadmill test during which calf muscle Sto(2) was continuously monitored. The 6MWT distance, Walking Impairment Questionnaire (WIQ), and ambulatory activity were monitored during 1 week.

RESULTS

All patients experienced symptoms during the treadmill test consistent with claudication. The groups were not significantly different on the primary outcomes of time to reach the minimum calf muscle Sto(2) (P = .350) or peak walking time (P = .238) during treadmill exercise. Patients with atypical leg pain had the highest daily ambulatory activity for total strides per day (P = .032), average daily cadence (P = .010), maximum cadences for durations between 5 minutes (P = .035) and 60 minutes (P = .029), speed score on the WIQ (P = .006), and lowest rating of perceived exertion at the end of the 6MWT (P = .017).

CONCLUSIONS

PAD patients with atypical leg pain have vascular-mediated limitations in exercise performance during standardized treadmill testing similar to patients with claudication and patients with leg pain on exertion and rest but have higher levels of daily ambulatory activity in the community setting and higher perceived ambulatory function.

The effects of including quality of life responses in models to predict walking performance of patients with intermittent claudication

OBJECTIVES

To examine the accuracy of previously developed prediction models of treadmill walking performance in patients with intermittent claudication (IC) due to peripheral arterial disease (PAD); and to examine the accuracy of new prediction models.

DESIGN

Analysis of data collected in a previous randomised clinical trial.

MATERIALS

Ninety-three assessments of 28 patients diagnosed with IC due to PAD.

METHODS

Patients undertook routine clinical assessments, quality of life (QOL) questionnaires and treadmill walking tests. Walking performance and estimates based on prediction models were compared via paired t-tests or Wilcoxon Rank Sum tests. Stepwise linear regression generated models to predict walking performance from clinical measures and QOL responses. Accuracy was determined as the absolute error between model estimates and patient results.

RESULTS

Walking performance was significantly underestimated (35-71% error) by previously developed prediction models. Models developed in the current study identified QOL responses as the most significant predictors of current walking performance but these models still resulted in substantial errors (19-84%).

CONCLUSIONS

Previously published predictors of walking performance significantly underestimated patient's ability in practise. Predictions based upon clinical measurements and QOL responses were developed however, their accuracy was also limited. Further research is needed regarding walking performance prediction to assist clinicians with assessment of PAD severity and treatment effectiveness.

Gender differences in daily ambulatory activity patterns in patients with intermittent claudication

OBJECTIVES

To compare the pattern of daily ambulatory activity in men and women with intermittent claudication, and to determine whether calf muscle hemoglobin oxygen saturation (StO2) is associated with daily ambulatory activity.

METHODS

Forty men and 41 women with peripheral arterial disease limited by intermittent claudication were assessed on their community-based ambulatory activity patterns for 1 week with an ankle-mounted step activity monitor and on calf muscle StO2 during a treadmill test.

RESULTS

Women had lower adjusted daily maximal cadence (mean±SE) for 5 continuous minutes of ambulation (26.2±1.2 strides/min vs 31.0±1.2 strides/min; P=.009), for 1 minute of ambulation (43.1±0.9 strides/min vs 47.2±0.9 strides/min; P=.004), and for intermittent ambulation determined by the peak activity index (26.3±1.2 strides/min vs 31.0±1.2 strides/min; P=.009). Women also had lower adjusted time to minimum calf muscle StO2 during exercise (P=.048), which was positively associated with maximal cadence for 5 continuous minutes (r=0.51; P<.01), maximal cadence for 1 minute (r=0.42; P<.05), and peak activity index (r=0.44; P<.05). These associations were not significant in men.

CONCLUSION

Women with intermittent claudication ambulate slower in the community setting than men, particularly for short continuous durations of up to 5 minutes and during intermittent ambulation at peak cadences. Furthermore, the daily ambulatory cadences of women are correlated with their calf muscle StO2 during exercise, as women who walk slower in the community setting reach their minimum calf muscle StO2 sooner than those who walk at faster paces. Women with intermittent claudication should be encouraged to not only walk more on a daily basis, but to do so at a pace that is faster than their preferred speed.

Gender and ethnic differences in arterial compliance in patients with intermittent claudication

OBJECTIVE

To assess the gender and ethnic differences in arterial compliance in patients with intermittent claudication.

METHODS

A total of 114 patients participated, including 38 Caucasian men, 32 Caucasian women, 16 African American men, and 28 African American women. Patients were assessed on large artery elasticity index (LAEI), small artery elasticity index (SAEI), age, weight, body mass index, ankle-brachial index (ABI), smoking status, and metabolic syndrome components.

RESULTS

Group differences were found for LAEI (P = .042), SAEI (P = .019), body mass index (P = .020), prevalence of elevated fasting glucose (P = .001), and prevalence of abdominal obesity (P = .025). Significant covariates for LAEI included age (P = .0002) and elevated triglycerides (P = .0719). LAEI (units = 10 mL x mm Hg) adjusted for age and triglycerides was 39% lower (P = .0005) in African Americans (11.4 +/- .90; mean +/- SE) than in Caucasians (15.8 +/- 0.72), whereas no significant difference (P = .7904) existed between men (13.8 +/- 0.81) and women (13.5 +/- 0.79). Significant covariates for SAEI included age (P = .0001), abdominal obesity (P = .0030), and elevated blood pressure (P = .0067). SAEI (units = 100 mL x mm Hg) adjusted for age, abdominal obesity, and elevated blood pressure was 32% lower (P = .0007) in African-Americans (2.8 +/- 0.3) than in Caucasians 4.1 +/- 0.2), and was 18% lower (P = .0442) in women (3.1 +/- 0.2) than in men (3.8 +/- 0.2).

CONCLUSION

African American patients with intermittent claudication have more impaired macrovascular and microvascular function than Caucasian patients, and women have more impaired microvascular function than men. These ethnic and gender differences in arterial compliance are evident even though ABI was similar among groups, suggesting that arterial compliance provides unique information to quantify vascular impairment in patients with intermittent claudication.