Predictors of walking capacity in patients with peripheral arterial disease

BACKGROUND

Walking capacity is severely impaired in patients with peripheral arterial disease (PAD). Given the prognostic importance of walking capacity, the level of evidence on possible predictors of walking capacity in patients with PAD is insufficient.

AIMS

To investigate the predictors of walking capacity in patients with PAD.

METHODS

A total of 51 patients with PAD were included in this cross-sectional study. Walking capacity was determined with 6‑minute walk test (6MWT) and walking impairment questionnaire (WIQ). Functional mobility was assessed with repeated sit-to-stand test (RSS) and timed up and go test (TUG). Hand-held dynamometer was used to measurement lower extremity muscle strength. Balance was assessed with Biodex Balance System-limit of stability (BBS-LOS). Fatigue was evaluated with fatigue impact scale (FIS).

RESULTS

There was a strong correlation between 6MWT walking distance and WIQ, two methods of assessing walking capacity (r = 0.835 p < 0.001). The 6MWT was correlated with RSS, TUG, lower extremity muscle strength, BBS-LOS and FIS. The WIQ was correlated with RSS, TUG, BBS-LOS and FIS. The RSS and FIS were independent determinants of the 6MWT and WIQ, accounting for 68% and 57% of the variance, respectively.

CONCLUSION

This study demonstrated that functional mobility and fatigue were independent predictors of walking capacity in patients with PAD. Both subjective and objective measurement methods can be used for determining the level of walking capacity in the patients with PAD.

Collateral Arteriogenesis Involves a Sympathetic Denervation That Is Associated With Abnormal α-Adrenergic Signaling and a Transient Loss of Vascular Tone

Stimulating collateral arteriogenesis is an attractive therapeutic target for peripheral artery disease (PAD). However, the potency of arteriogenesis-stimulation in animal models has not been matched with efficacy in clinical trials. This may be because the presence of enlarged collaterals is not sufficient to relieve symptoms of PAD, suggesting that collateral function is also important. Specifically, collaterals are the primary site of vascular resistance following arterial occlusion, and impaired collateral vasodilation could impact downstream tissue perfusion and limb function. Therefore, we evaluated the effects of arteriogenesis on collateral vascular reactivity. Following femoral artery ligation in the mouse hindlimb, collateral functional vasodilation was impaired at day 7 (17 ± 3 vs. 60 ± 8%) but restored by day 28. This impairment was due to a high resting diameter (73 ± 4 μm at rest vs. 84 ± 3 μm dilated), which does not appear to be a beneficial effect of arteriogenesis because increasing tissue metabolic demand through voluntary exercise decreased resting diameter and restored vascular reactivity at day 7. The high diameter in sedentary animals was not due to sustained NO-dependent vasodilation or defective myogenic constriction, as there were no differences between the enlarged and native collaterals in response to eNOS inhibition with L-NAME or L-type calcium channel inhibition with nifedipine, respectively. Surprisingly, in the context of reduced vascular tone, vasoconstriction in response to the α-adrenergic agonist norepinephrine was enhanced in the enlarged collateral (−62 ± 2 vs. −37 ± 2%) while vasodilation in response to the α-adrenergic antagonist prazosin was reduced (6 ± 4% vs. 22 ± 16%), indicating a lack of α-adrenergic receptor activation by endogenous norepinephrine and suggesting a denervation of the neuroeffector junction. Staining for tyrosine hydroxylase demonstrated sympathetic denervation, with neurons occupying less area and located further from the enlarged collateral at day 7. Inversely, MMP2 presence surrounding the enlarged collateral was greater at day 7, suggesting that denervation may be related to extracellular matrix degradation during arteriogenesis. Further investigation on vascular wall maturation and the functionality of enlarged collaterals holds promise for identifying novel therapeutic targets to enhance arteriogenesis in patients with PAD.

Pathophysiology of Peripheral Arterial Disease (PAD): A Review on Oxidative Disorders

Peripheral arterial disease (PAD) is an atherosclerotic disease that affects a wide range of the world’s population, reaching up to 200 million individuals worldwide. PAD particularly affects elderly individuals (>65 years old). PAD is often underdiagnosed or underestimated, although specificity in diagnosis is shown by an ankle/brachial approach, and the high cardiovascular event risk that affected the PAD patients. A number of pathophysiologic pathways operate in chronic arterial ischemia of lower limbs, giving the possibility to improve therapeutic strategies and the outcome of patients. This review aims to provide a well detailed description of such fundamental issues as physical exercise, biochemistry of physical exercise, skeletal muscle in PAD, heme oxygenase 1 (HO-1) in PAD, and antioxidants in PAD. These issues are closely related to the oxidative stress in PAD. We want to draw attention to the pathophysiologic pathways that are considered to be beneficial in order to achieve more effective options to treat PAD patients.

Combined Aerobic and Resistance Exercise in Walking Performance of Patients With Intermittent Claudication: Systematic Review

Background: The short-term benefits of aerobic and resistance exercise in subjects affected by Peripheral Arterial Disease (PAD) are scarcely examined in interaction. This study aimed to identify the effects of combined aerobic and resistance exercise programs on walking performance compared with isolated aerobic exercise or with the usual care in patients with intermittent claudication.

Methods: A systematic review was conducted following the PRISMA statement. A total of five electronic databases were searched (until October 2019) for randomized and non-randomized controlled trials. The focus comprised PAD patients with intermittent claudication who performed a combined aerobic and resistance exercise program that assessed the walking performance.

Results: Seven studies include combined aerobic and resistance exercise vs. isolated aerobic or vs. usual care. The studies represented a sample size of 337 participants. The follow-up ranged from 4 to 12 weeks, 2 to 5 times-per-week. The risk of bias in the trials was a deemed moderate-to-high risk. After the interventions, the percent change in walking performance outcomes had a large variation. In the combined and isolated aerobic programs, the walking performance always improved, while in the usual care group oscillates between the deterioration and the improvement in all outcomes. Combined exercise and isolated aerobic exercise improved the claudication onset distance from 11 to 396%, and 30 to 422%, the absolute claudication distance from 81 to 197%, and 53 to 121%, and the maximal walking distance around 23 and 10%, respectively.

Conclusions: Currently, there is insufficient evidence about the effects of combined aerobic and resistance exercise compared to isolated aerobic exercise or usual care on walking performance. However, despite the low quality of evidence, the combined aerobic and resistance exercise seems to be an effective strategy to improve walking performance in patients with intermittent claudication. These combined exercise modes or isolated aerobic exercise produce positive and significant results on walking performance. The usual care approach has a trend to deteriorate the walking performance. Thus, given the scarcity of data, new randomized controlled trial studies that include assessments of cardiovascular risk factors are urgently required to better determine the effect of this exercise combination.

Impact of peripheral artery disease on the quality of life of patients with diabetes mellitus

BACKGROUND

Diabetes Mellitus (DM) has become one of the main problems of health, which might lead to a series of complications, such as peripheral vasculopathy.

PURPOSE

The objectives of this study were to determine whether peripheral artery disease affects the quality of life and pain level and functionality of the foot in patients with DM.

METHODS

The sample consisted of 150 participants: with peripheral vasculopathy and DM, with DM, without peripheral vasculopathy, with neither DM nor peripheral vasculopathy. Questionnaires SF-12, EuroQol 5D, FFI, and the Manchester Foot Pain and Disability Index were used.

RESULTS

There were significant differences in the physical component of SF-12, in the visual health scale of EuroQol 5D and the functional component of the Manchester Foot Pain and Disability Index the best score was obtained by group C.

CONCLUSION

Peripheral vasculopathy influences the quality of life of patients with DM and causes functional limitations.

Relationship between walking capacity and ambulatory blood pressure in patients with intermittent claudication

OBJECTIVE

Patients with intermittent claudication (IC) often have high blood pressure (BP), which increases their cardiovascular risk. However, whether walking capacity is associated with BP levels in patients with IC remains unknown. Therefore, this study was designed to investigate whether the total walking distance is associated with ambulatory BP in patients with IC.

PARTICIPANTS AND METHODS

This was a cross-sectional study of 75 patients with IC (58 men; 17 women). A maximal treadmill test (Gardner protocol) was performed to assess total walking distance in these patients. Furthermore, ambulatory BP, heart rate, rate-pressure product, and BP load were obtained over a 24-h period. One-way analysis of variance and multiple linear regression were carried out.

RESULTS

Walking capacity was correlated negatively with the following: (i) asleep systolic BP, diastolic BP, mean BP and heart rate; (ii) 24-h, awake and asleep RPP; and (iii) awake and asleep systolic BP load (all P<0.05). These associations occurred irrespective of confounders such as age, sex, BMI, smoking status, and number of antihypertensive medications.

CONCLUSION

A better walking capacity is associated with lower ambulatory BP parameters in patients with IC.

Prediction of 6-minute walk performance in patients with peripheral artery disease

BACKGROUND

Peripheral artery disease (PAD) is a highly prevalent disease that impairs walking ability. Walking tests, such as the 6-minute walk test (6MWT) and 4-meter walk test, are commonly used to assess exercise endurance and ambulatory function over a short distance, respectively. The 6MWT performance is predictive of PAD severity and disease outcomes, but it is not feasible in many clinical settings because it requires a long walkway to serve as the test route and lengthens clinic visits. As an alternative, the 4-meter walk test is convenient, inexpensive, and repeatable, but whether it accurately predicts endurance performance in the long-distance 6MWT is not known. The goal of this study was to develop a statistical model to predict 6MWT gait speed from 4-meter walk test results and clinical characteristics among patients with PAD.

METHODS

Measures of 6MWT gait speed were derived from 183 patients with symptomatic PAD who were evaluated at the University of Oklahoma Health Sciences Center (2004-2012). The testing procedures and research personnel remained constant throughout the duration of the study. Independent variables included demographic and clinical information and 4-meter walk test gait speed. Fivefold cross validation and manual backward selection were used for model selection. Adjusted R² and corrected Akaike information criterion were applied to quantify the predictive performance of the regression models.

RESULTS

A total of 183 people (54% male; mean age, 65 [standard deviation (SD), 10] years) with moderate PAD severity (ankle-brachial index [ABI]; mean, 0.72 [SD, 0.24]) performed the walking tests. Participants covered an average distance of 335 (SD, 97) m distance in the 6MWT. The 4-meter walk gait speed, ABI, and dyspnea were independent predictors of 6MWT speed in the multivariate model (adjusted R² = 0.55). The model resulted in 95% prediction interval widths of 30 m for mean and 260 m for individual predicted 6MWT distance measures.

CONCLUSIONS

Slower 4-meter walking speed, lower ABI, and presence of dyspnea all predict slower 6MWT gait speed, which corresponds to shorter 6MWT distance. Prediction of group means is reasonably precise; however, prediction of individual patient 6MWT performance is imprecise relative to between-group differences that are clinically important.

Factors Associated with Sedentary Behavior in Patients with Intermittent Claudication

OBJECTIVES

Time spent in sedentary behavior has been associated with cardio-metabolic risk factors in the general population and in patients with symptomatic peripheral artery disease (PAD). Given the association of sedentary behavior and poor health outcomes, it is important to identify factors associated with sedentary behavior in these patients. The aim of this study was to identify factors associated with the sedentary time in patients with symptomatic PAD.

METHODS

The sample included 297 patients with symptomatic PAD. Sedentary behavior was assessed using a step activity monitor and the patients were divided into tertiles. Demographic data, body mass index, comorbid conditions, and measures of severity of PAD (ankle brachial index, ischemic window, claudication measurements, peak oxygen uptake and walking economy) were obtained.

RESULTS

Patients in the highest tertile (i.e. more sedentary) had a higher body mass index and a higher prevalence of diabetes mellitus, metabolic syndrome, and obesity than patients in the lowest tertile, whereas their peak walking time, peak oxygen uptake, and walking economy were lower (p < .05 for all). Using multiple regression procedures, the factors associated with the sedentary time were male sex (b = .217, R² = .180, p = .001), body mass index (b = .154, R² = .059, p = .013), peak walking time (b = -.360, R² = .066, p ≤ .001), and walking economy (b = -.187, R² = .142, p = .004).

CONCLUSION

In patients with symptomatic PAD, greater time spent in sedentary behavior was found in men, and in patients with higher body mass index, lower peak walking time, and lower walking economy.