Randomized reliability study evaluating constant-load and graded-exercise treadmill test for intermittent claudication

Objective assessment of functional capacity in patients with peripheral artery disease: a narrative review

INTRODUCTION

Peripheral artery disease (PAD) patients with claudication symptoms exhibit impaired functional capacity, which has been associated with disease severity, worse quality of life and higher risk of cardiovascular events. Different tests have been used to assess functional capacity in PAD patients. Therefore, understanding the characteristics, strengths and limitations of these tests are important to support the choice of tests to be used in clinical practice.

AREAS COVERED

This review summarizes the main methods to assess functional capacity in PAD patients, discussing their psychometric properties, applications, and limitations.

EXPERT OPINION

Robust evidence supports the use of treadmill and six-minute walk tests in PAD patients, as their results are associated with clinically meaningful outcomes, adequate psychometric properties and are sensitive to effects of interventions. On the other hand, other functional tests (Shuttle-walk test, outdoor walking capacity test, timed-up and go, four-meter walk test, heel-rise test, short physical performance battery and modified physical performance battery) are related to activities of daily living and do not require sophisticated equipment and can be easily used in clinical practice. However, these other tests still need evidence regarding their clinical relevance, reliability, and ability to detect long-term intervention changes, providing further investigation directions.

Comparison of the influence of supportive and sensorimotor insoles in the muscle activity of tibialis anterior and peroneus longus in combat boots

INTRODUCTION

Flatfoot is a very common static deformity. It occurs frequently in soldiers and causes problems in the lower extremities. There is a lack of data regarding therapy with insoles, especially with sensorimotor insoles. The objective of this study was to investigate the influence in muscle activity of supporting/correcting and sensorimotor insoles in combat boots in the muscles of the lower limb and thus to draw conclusions according to the benefits of insole therapy in military footwear.

METHODS

73 patients (12 female, 61 males; average age: 30.8 ± 7.9 years) with pes planovalgus deformity were included in this prospective randomized placebo-controlled study. For intervention supporting (N = 23), sensorimotor (N = 28) and placebo insoles (N = 22) were used. During gait analysis muscle activity was measured by means of surface electromyography (EMG) of the tibialis anterior and peroneus longus muscle in combat boots with and without insoles. Statistical evaluation was performed using two-factor ANOVA with repeated measures.

RESULTS

EMG measures (amplitude, integral, maximum, mean) showed mainly activating effects in the peroneus longus muscle in the case of sensorimotor and activity reductions in supporting insoles. Comparing effects of different kinds of insoles to the peroneus longus muscle, significant differences could be shown. No significant differences in muscular activation were observed for the tibialis anterior muscle.

CONCLUSION

Even in combat boots effects of sensorimotor insoles on the peroneus longus muscle can be detected. The expected effects, attributed to the different kinds of insole, could be observed, too. While sensorimotor insoles had an activating kind of effect, supportive insoles reduced muscular activity of the peroneus longus. In contrast for the tibialis anterior muscle no clear conclusion could be drawn. Its muscular activity seems not to be influenced by insoles in combat boots. However, it remains unclear whether clinical long term effects, e.g. pain and function, can be improved.

Supervised physical activity in patients with symptomatic peripheral arterial disease: protocol for a randomized clinical trial (ARTPERfit Study)

INTRODUCTION

Peripheral arterial disease (PAD) is a marker of cardiovascular morbidity, causing disability, loss of mobility and poor quality of life, manifesting clinically in the form of intermittent claudication (IC). Physical exercise increases the distance walked and improves quality of life. The aim of our study will be increased walking distance prolonging the time of onset of pain in patients with symptomatic PAD (IC).

METHODS AND ANALYSIS

This study will be performed in Mataró Hospital's vascular surgery service and School of Health Sciences, TecnoCampus. This population comes from 15 primary healthcare centres ofNorth Barcelona, Spain (450 000 inhabitants).This study will be a four-group parallel, longitudinal, randomised controlled trial, blind to analysis.The main primary outcome of this study will be the improvement in pain-free walking distance. Others primary objectives are and improvement in functional status, quality of life and Ankle-Brachial Index (ABI). Secondary outcomes will be the analysis of cardiorespiratory fitness, evaluation of muscle fitness, determine the maintenance of primary objectives at 6 and 12 months.We will be included 124 patients (31 per group). The changes of the outcome (Barthel, SF-12, VascQOL-6, ABI) of the three intervention groups vs the control group at 3, 6 and 12 months will be compared, both continuously (linear regression) and categorically (logistic regression). A person who has not performed at least 75% of the training will be considered to have not completed the intervention.

ETHICS AND DISSEMINATION

The study will be conducted according to the Declaration of Helsinki . It was approved by the Ethics Committee of the Research Institute Primary Health IDIAP Jordi Gol (20/035 P),Barcelona 6 October 2020. Informed consent will be obtained from all patients before the start of the study. We will disseminate results through academic papers and conference presentations.

TRIAL REGISTRATION NUMBER

NCT04578990.

Machine Learning Confirms Nonlinear Relationship between Severity of Peripheral Arterial Disease, Functional Limitation and Symptom Severity

BACKGROUND

Peripheral arterial disease (PAD) involves arterial blockages in the body, except those serving the heart and brain. We explore the relationship of functional limitation and PAD symptoms obtained from a quality-of-life questionnaire about the severity of the disease. We used a supervised artificial intelligence-based method of data analyses known as machine learning (ML) to demonstrate a nonlinear relationship between symptoms and functional limitation amongst patients with and without PAD.

OBJECTIVES

This paper will demonstrate the use of machine learning to explore the relationship between functional limitation and symptom severity to PAD severity.

METHODS

We performed supervised machine learning and graphical analysis, analyzing 703 patients from an administrative database with data comprising the toe-brachial index (TBI), baseline demographics and symptom score(s) derived from a modified vascular quality-of-life questionnaire, calf circumference in centimeters and a six-minute walk (distance in meters).

RESULTS

Graphical analysis upon categorizing patients into critical limb ischemia (CLI), severe PAD, moderate PAD and no PAD demonstrated a decrease in walking distance as symptoms worsened and the relationship appeared nonlinear. A supervised ML ensemble (random forest, neural network, generalized linear model) found symptom score, calf circumference (cm), age in years, and six-minute walk (distance in meters) to be important variables to predict PAD. Graphical analysis of a six-minute walk distance against each of the other variables categorized by PAD status showed nonlinear relationships. For low symptom scores, a six-minute walk test (6MWT) demonstrated high specificity for PAD.

CONCLUSIONS

PAD patients with the greatest functional limitation may sometimes be asymptomatic. Patients without PAD show no relationship between functional limitation and symptoms. Machine learning allows exploration of nonlinear relationships. A simple linear model alone would have overlooked or considered such a nonlinear relationship unimportant.

Exercise for intermittent claudication

BACKGROUND

Exercise programmes are a relatively inexpensive, low-risk option compared with other, more invasive therapies for treatment of leg pain on walking (intermittent claudication (IC)). This is the fourth update of a review first published in 1998.

OBJECTIVES

Our goal was to determine whether an exercise programme was effective in alleviating symptoms and increasing walking treadmill distances and walking times in people with intermittent claudication. Secondary objectives were to determine whether exercise was effective in preventing deterioration of underlying disease, reducing cardiovascular events, and improving quality of life.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (last searched 15 November 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 10) via the Cochrane Register of Studies Online, along with trials registries.

SELECTION CRITERIA

Randomised controlled trials of an exercise regimen versus control or versus medical therapy for people with IC due to peripheral arterial disease (PAD). We included any exercise programme or regimen used for treatment of IC, such as walking, skipping, and running. Inclusion of trials was not affected by duration, frequency, or intensity of the exercise programme. Outcome measures collected included treadmill walking distance (time to onset of pain or pain-free walking distance and maximum walking time or maximum walking distance), ankle brachial index (ABI), quality of life, morbidity, or amputation; if none of these was reported, we did not include the trial in this review.

DATA COLLECTION AND ANALYSIS

For this update (2017), RAL and AH selected trials and extracted data independently. We assessed study quality by using the Cochrane 'Risk of bias' tool. We analysed continuous data by determining mean differences (MDs) and 95% confidence intervals (CIs), and dichotomous data by determining risk ratios (RRs) and 95% CIs. We pooled data using a fixed-effect model unless we identified significant heterogeneity, in which case we used a random-effects model. We used the GRADE approach to assess the overall quality of evidence supporting the outcomes assessed in this review.

MAIN RESULTS

We included two new studies in this update and identified additional publications for previously included studies, bringing the total number of studies meeting the inclusion criteria to 32, and involving a total of 1835 participants with stable leg pain. The follow-up period ranged from two weeks to two years. Types of exercise varied from strength training to polestriding and upper or lower limb exercises; supervised sessions were generally held at least twice a week. Most trials used a treadmill walking test for one of the primary outcome measures. The methodological quality of included trials was moderate, mainly owing to absence of relevant information. Most trials were small and included 20 to 49 participants. Twenty-seven trials compared exercise versus usual care or placebo, and the five remaining trials compared exercise versus medication (pentoxifylline, iloprost, antiplatelet agents, and vitamin E) or pneumatic calf compression; we generally excluded people with various medical conditions or other pre-existing limitations to their exercise capacity.Meta-analysis from nine studies with 391 participants showed overall improvement in pain-free walking distance in the exercise group compared with the no exercise group (MD 82.11 m, 95% CI 71.73 to 92.48, P < 0.00001, high-quality evidence). Data also showed benefit from exercise in improved maximum walking distance (MD 120.36 m, 95% CI 50.79 to 189.92, P < 0.0007, high-quality evidence), as revealed by pooling data from 10 studies with 500 participants. Improvements were seen for up to two years.Exercise did not improve the ABI (MD 0.04, 95% CI 0.00 to 0.08, 13 trials, 570 participants, moderate-quality evidence). Limited data were available for the outcomes of mortality and amputation; trials provided no evidence of an effect of exercise, when compared with placebo or usual care, on mortality (RR 0.92, 95% CI 0.39 to 2.17, 5 trials, 540 participants, moderate-quality evidence) or amputation (RR 0.20, 95% CI 0.01 to 4.15, 1 trial, 177 participants, low-quality evidence).Researchers measured quality of life using Short Form (SF)-36 at three and six months. At three months, the domains 'physical function', 'vitality', and 'role physical' improved with exercise; however this was a limited finding, as it was reported by only two trials. At six months, meta-analysis showed improvement in 'physical summary score' (MD 2.15, 95% CI 1.26 to 3.04, P = 0.02, 5 trials, 429 participants, moderate-quality evidence) and in 'mental summary score' (MD 3.76, 95% CI 2.70 to 4.82, P < 0.01, 4 trials, 343 participants, moderate-quality evidence) secondary to exercise. Two trials reported the remaining domains of the SF-36. Data showed improvements secondary to exercise in 'physical function' and 'general health'. The other domains - 'role physical', 'bodily pain', 'vitality', 'social', 'role emotional', and 'mental health' - did not show improvement at six months.Evidence was generally limited in trials comparing exercise versus antiplatelet therapy, pentoxifylline, iloprost, vitamin E, and pneumatic foot and calf compression owing to small numbers of trials and participants.Review authors used GRADE to assess the evidence presented in this review and determined that quality was moderate to high. Although results showed significant heterogeneity between trials, populations and outcomes were comparable overall, with findings relevant to the claudicant population. Results were pooled for large sample sizes - over 300 participants for most outcomes - using reproducible methods.

AUTHORS' CONCLUSIONS

High-quality evidence shows that exercise programmes provided important benefit compared with placebo or usual care in improving both pain-free and maximum walking distance in people with leg pain from IC who were considered to be fit for exercise intervention. Exercise did not improve ABI, and we found no evidence of an effect of exercise on amputation or mortality. Exercise may improve quality of life when compared with placebo or usual care. As time has progressed, the trials undertaken have begun to include exercise versus exercise or other modalities; therefore we can include fewer of the new trials in this update.

Diagnostic value of peripheral fractional flow reserve in isolated iliac artery stenosis: a comparison with the post-exercise ankle-brachial index

PURPOSE

To examine in claudicant patients with aortoiliac lesions the relationship between the post-exercise ankle-brachial index (ABI) and the peripheral fractional flow reserve (p-FFR), a physiological test that has heretofore been used to assess coronary and renal artery stenosis.

METHODS

Sixteen male patients (mean age 68.1±7.5 years) with isolated iliac artery lesions detected by ultrasound in 17 limbs were enrolled in this study. Resting ABI was measured and a treadmill test was administered to measure the post-exercise ABI. During angiography, the p-FFR was measured using a pressure guidewire after administration of papaverine to induce hyperemia. Changes in the ABI during exercise and p-FFR at hyperemia were calculated.

RESULTS

The mean resting ABI and post-exercise ABI were 0.87±0.12 and 0.65±0.24, respectively. There was no complication during the measurement of p-FFR. The mean p-FFR at hyperemia was 0.71±0.14. A significant linear correlation was observed between post-exercise ABI and p-FFR at hyperemia (r=0.857, p<0.001), which was stronger than the correlation between post-exercise ABI and peak-to-peak pressure gradient at hyperemia (r= -0.626, p=0.013).

CONCLUSIONS

Measuring p-FFR appears to be a feasible and safe procedure, and there is a significant linear correlation between post-exercise ABI and p-FFR in aortoiliac lesions. The p-FFR was more accurate than a peak-to-peak pressure gradient in assessing the physiological significance of a stenosis. Though larger studies are required, p-FFR might be used to physiologically assess stenosis in PAD patients with isolated aortoiliac lesions.

Exercise for intermittent claudication

BACKGROUND

Exercise programmes are a relatively inexpensive, low-risk option compared with other more invasive therapies for leg pain on walking (intermittent claudication (IC)). This is an update of a review first published in 1998.

OBJECTIVES

The prime objective of this review was to determine whether an exercise programme in people with intermittent claudication was effective in alleviating symptoms and increasing walking treadmill distances and walking times. Secondary objectives were to determine whether exercise was effective in preventing deterioration of underlying disease, reducing cardiovascular events and improving quality of life.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched September 2013) and CENTRAL (2013, Issue 8).

SELECTION CRITERIA

Randomised controlled trials of an exercise regimen versus control or versus medical therapy in people with IC due to peripheral arterial disease. Any exercise programme or regimen used in the treatment of intermittent claudication was included, such as walking, skipping and running. Inclusion of trials was not affected by the duration, frequency or intensity of the exercise programme. Outcome measures collected included treadmill walking distance (time to onset of pain or pain-free walking distance and maximum walking time or maximal walking distance), ankle brachial index (ABI), quality of life, morbidity or amputation; if none of these were reported the trial was not included in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality.

MAIN RESULTS

Eleven additional studies were included in this update making a total of 30 trials which met the inclusion criteria, involving a total of 1816 participants with stable leg pain. The follow-up period ranged from two weeks to two years. The types of exercise varied from strength training to polestriding and upper or lower limb exercises; generally supervised sessions were at least twice a week. Most trials used a treadmill walking test for one of the outcome measures. Quality of the included trials was moderate, mainly due to an absence of relevant information. The majority of trials were small with 20 to 49 participants. Twenty trials compared exercise with usual care or placebo, the remainder of the trials compared exercise to medication (pentoxifylline, iloprost, antiplatelet agents and vitamin E) or pneumatic calf compression; people with various medical conditions or other pre-existing limitations to their exercise capacity were generally excluded.Overall, when taking the first time point reported in each of the studies, exercise significantly improved maximal walking time when compared with usual care or placebo: mean difference (MD) 4.51 minutes (95% confidence interval (CI) 3.11 to 5.92) with an overall improvement in walking ability of approximately 50% to 200%. Walking distances were also significantly improved: pain-free walking distance MD 82.29 metres (95% CI 71.86 to 92.72) and maximum walking distance MD 108.99 metres (95% CI 38.20 to 179.78). Improvements were seen for up to two years, and subgroup analyses were performed at three, six and 12 months where possible. Exercise did not improve the ABI (MD 0.05, 95% CI 0.00 to 0.09). The effect of exercise, when compared with placebo or usual care, was inconclusive on mortality, amputation and peak exercise calf blood flow due to limited data. No data were given on non-fatal cardiovascular events.Quality of life measured using the Short Form (SF)-36 was reported at three and six months. At three months, physical function, vitality and role physical all significantly improved with exercise, however this was a limited finding as this measure was only reported in two trials. At six months five trials reported outcomes of a significantly improved physical summary score and mental summary score secondary to exercise. Only two trials reported improvements in other domains, physical function and general health.Evidence was generally limited for exercise compared with antiplatelet therapy, pentoxifylline, iloprost, vitamin E and pneumatic foot and calf compression due to small numbers of trials and participants.

AUTHORS' CONCLUSIONS

Exercise programmes are of significant benefit compared with placebo or usual care in improving walking time and distance in people with leg pain from IC who were considered to be fit for exercise intervention.

Diabetes status differentiates endothelial function and plasma nitrite response to exercise stress in peripheral arterial disease following supervised training

AIMS

To determine if type 2 diabetes mellitus (T2D) differentiates endothelial function and plasma nitrite response (a marker of nitric oxide bioavailability) during exercise in peripheral arterial disease (PAD) subjects prior to and following 3 months supervised exercise training (SET).

METHODS

In subjects with T2D+PAD (n = 13) and PAD-only (n = 14), endothelial function was measured using brachial artery flow-mediated dilation. On a separate day, venous blood draws were performed at rest and 10 min following a symptom-limited graded treadmill test (SL-GXT). Plasma samples were snap-frozen for analysis of nitrite by reductive chemiluminescence. All testing was repeated following 3 months of SET.

RESULTS

Prior to training both groups demonstrated endothelial dysfunction, which was correlated with a net decrease in plasma nitrite following a SL-GXT (p ≤ 0.05). Following SET, the PAD-only group demonstrated an improvement in endothelial function (p ≤ 0.05) and COT (p ≤ 0.05), which was related to a net increase in plasma nitrite following the SL-GXT (both p ≤ 0.05). The T2D+PAD group had none of these increases.

CONCLUSIONS

T2D in the presence of PAD attenuated improvements in endothelial function, net plasma nitrite, and COT following SET. This suggests that T2D maybe associated with an inability to endogenously increase vascular NO bioavailability to SET.

Successful treatment of thromboangiitis obliterans (Buerger's disease) with immunoadsorption: results of a pilot study

BACKGROUND

No established therapy is available for patients with thromboangiitis obliterans (TAO) and critical limb ischemia. Since abnormalities of the immune system appear to be involved in the pathogenesis, we investigated in this pilot study the efficiency of Ig immunoadsorption (IA) therapy.

METHODS

Ten patients with advanced TAO underwent a single IA course over five consecutive days. Before IA angiography was performed. In addition, the following were conducted prior to IA, directly after, as well as 1, 3, and 6 months after IA: clinical examination, pain scale (0-10), treadmill test for evaluation of maximum walking distances, and several angiological methods for evaluation of disease extent: photoplethysmography, ultrasound Doppler, and transcutaneous assessment of partial carbon dioxide (tcPCO(2)) and oxygen (tcPCO(2)) pressure.

RESULTS

Immunoadsorption treatment was tolerated without side effects. Pain intensity decreased rapidly from 7.7 ± 0.8 (mean ± SEM) before treatment to 2.0 ± 1.2 at the second day of IA. One month after IA, all patients were without pain. This functional amelioration persisted over the follow-up period of 6 months. Correspondingly, maximum walking distances significantly increased from 301.7 ± 191.4 to 727.0 ± 192.7 m immediately after IA, and further continuously up to 1,811.0 ± 223.7 at 6 months after IA. Healing of ischemic ulcerations was observed in all patients during follow-up. (tcPCO(2)) and (tcPCO(2)) values as well as photopletysmographic data that were severely compromised before IA reflecting reduced tissue oxygenation and perfusion showed rapid amelioration reaching normal values at 1 month.

CONCLUSION

Anti-Ig IA appears to be an effective therapeutic option for patients with advanced TAO.

Functional claudication distance: a reliable and valid measurement to assess functional limitation in patients with intermittent claudication

Background

Disease severity and functional impairment in patients with intermittent claudication is usually quantified by the measurement of pain-free walking distance (intermittent claudication distance, ICD) and maximal walking distance (absolute claudication distance, ACD). However, the distance at which a patient would prefer to stop because of claudication pain seems a definition that is more correspondent with the actual daily life walking distance. We conducted a study in which the distance a patient prefers to stop was defined as the functional claudication distance (FCD), and estimated the reliability and validity of this measurement.

Methods

In this clinical validity study we included patients with intermittent claudication, following a supervised exercise therapy program. The first study part consisted of two standardised treadmill tests. During each test ICD, FCD and ACD were determined. Primary endpoint was the reliability as represented by the calculated intra-class correlation coefficients. In the second study part patients performed a standardised treadmill test and filled out the Rand-36 questionnaire. Spearman's rho was calculated to assess validity.

Results

The intra-class correlation coefficients of ICD, FCD and ACD were 0.940, 0.959, and 0.975 respectively. FCD correlated significantly with five out of nine domains, namely physical function (rho = 0.571), physical role (rho = 0.532), vitality (rho = 0.416), pain (rho = 0.416) and health change (rho = 0.414).

Conclusion

FCD is a reliable and valid measurement for determining functional capacity in trained patients with intermittent claudication. Furthermore it seems that FCD better reflects the actual functional impairment. In future studies, FCD could be used alongside ICD and ACD.

Exercise for intermittent claudication

BACKGROUND

Exercise programmes are a relatively inexpensive, low-risk option compared with other more invasive therapies for leg pain on walking (intermittent claudication (IC)).

OBJECTIVES

To determine the effects of exercise programmes on IC, particularly in respect of reduction of symptoms on walking and improvement in quality of life.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last search February 2008) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2008, Issue 1.

SELECTION CRITERIA

Randomised controlled trials of exercise regimens in people with IC due to peripheral arterial disease.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality.

MAIN RESULTS

Twenty-two trials met the inclusion criteria involving a total of 1200 participants with stable leg pain. Follow-up period was from two weeks to two years. There was some variation in the exercise regimens used, all recommended at least two sessions weekly of mostly supervised exercise. All trials used a treadmill walking test for one of the outcome measures. Quality of the included trials was good, though the majority of trials were small with 20 to 49 participants. Fourteen trials compared exercise with usual care or placebo; patients with various medical conditions or other pre-existing limitations to their exercise capacity were generally excluded.Compared with usual care or placebo, exercise significantly improved maximal walking time: mean difference (MD) 5.12 minutes (95% confidence interval (CI) 4.51 to 5.72;) with an overall improvement in walking ability of approximately 50% to 200%; exercise did not affect the ankle brachial pressure index (ABPI) (MD -0.01, 95% CI -0.05 to 0.04). Walking distances were also significantly improved: pain-free walking distance MD 82.19 metres (95% CI 71.73 to 92.65) and maximum walking distance MD 113.20 metres (95% CI 94.96 to 131.43). Improvements were seen for up to two years. The effect of exercise compared with placebo or usual care was inconclusive on mortality, amputation and peak exercise calf blood flow due to limited data.Evidence was generally limited for exercise compared with surgical intervention, angioplasty, antiplatelet therapy, pentoxifylline, iloprost and pneumatic foot and calf compression due to small numbers of trials and participants. Angioplasty may produce greater improvements than exercise in the short term but this effect may not be sustained.

AUTHORS' CONCLUSIONS

Exercise programmes were of significant benefit compared with placebo or usual care in improving walking time and distance in selected patients with leg pain from IC.

Confiabilidade de testes de caminhada em pacientes claudicantes: estudo piloto

CONTEXTO: Uma vez que a obstrução arterial periférica pode se apresentar de maneira difusa, com clínica diversa e com resultados de intervenção variados, é fundamental que a avaliação dos pacientes com doença arterial obstrutiva periférica seja feita com instrumentos que possam apresentar dados objetivos e reprodutíveis. OBJETIVO: Investigar e contrastar a confiabilidade do teste de caminhada de 6 minutos (T6M) com teste de deslocamento bidirecional progressivo (TDBP) em indivíduos claudicantes portadores de doença arterial obstrutiva periférica. MÉTODOS: Quatorze pacientes em estágio II de Fontaine participaram deste estudo piloto. Onze pacientes realizaram ambos os testes e três realizaram apenas T6M. Após familiarização, os pacientes foram avaliados em duas ocasiões distintas com intervalo máximo de 1 semana entre si. O coeficiente de correlação de intraclasse (ICC2,1) foi utilizado para avaliação da reprodutibilidade teste-reteste. RESULTADOS: A média da distância máxima de caminhada no teste e no reteste no T6M foi de 397,04±120,74 e 408,6±153,64 metros (p = 0,58), respectivamente, com ICC = 0,87 (p = 0,00005); já no TDBP, a média foi de 345±145,75 metros e, no reteste, de 345,91±127,97 (p = 0,92), com ICC = 0,99 (p = 0,00005). O tempo médio para surgimento da dor inicial, em segundos, com o T6M, foi de 172,25±88,23 (teste) e 148,58±70,36 (reteste) (p = 0,13), com ICC = 0,81 (p = 0,0004). No TDBP, o tempo médio foi de 282±141,90 (teste) e 267,14±150,58 (reteste) (p = 0,55), com ICC = 0,91 (p = 0,0008). CONCLUSÃO: Ambos os testes de caminhada são confiáveis e úteis para avaliação clínico-funcional desses pacientes. O TDBP, entretanto, gerou índices de confiabilidade mais elevados, podendo ser melhor opção para avaliação da performance desses indivíduos.

Correlação entre o índice tornozelo-braço antes e após teste de deslocamento bidirecional progressivo

CONTEXTO: A alteração de fluxo sangüíneo observada nos pacientes com doença arterial obstrutiva periférica (DAOP) contribui para a redução da capacidade deambulatórida. Entretanto, ainda existe uma grande variabilidade nas correlações entre medidas inferenciais de comprometimento de fluxo e testes de deslocamento. OBJETIVO: Estabelecer o nível de correlação entre as medidas do índice tornozelo-braço (ITB), pré e pós-esforço, com um novo teste de deambulação chamado teste de deslocamento bidirecional progressivo (TDBP). MÉTODOS: Vinte e um pacientes claudicantes, com diagnóstico de DAOP, tiveram registrados o ITB antes e após a realização de um teste de caminhada no solo, com controle externo e progressivo de velocidade (TDBP). RESULTADOS: Foram registrados a distância (261,07±160,63 metros), o tempo (292,30±122,61 segundos) e a velocidade (1,23±0,34 m/s) obtidos no início do surgimento de sintoma claudicante, bem como durante o surgimento de sintoma limitante (369,52±157,97 metros, 377,71±104,60 segundos, 1,46±0,29 m/s, respectivamente). A média do ITB de repouso foi de 0,66±0,14, e de pós-esforço foi de 0,42±0,19. Não se observou nenhuma correlação importante entre as variáveis do teste (distância, tempo e velocidade) com o ITB de repouso e nem após esforço. CONCLUSÃO: O tempo, velocidade e distância de surgimento de sintoma claudicante e de sintoma claudicante limitante durante o teste de caminhada progressiva são independentes da medida inferencial de fluxo sangüíneo através do ITB de repouso e pós-exercício.

The Reliability of Walking Tests in People with Claudication

OBJECTIVE

To contrast the reliability of the 6-min walking test (6MW) with that of the shuttle walking test (SWT) in patients with intermittent claudication attributable to peripheral obstructive arterial disease (POAD), and to examine the relationships of the walking tests, medical outcomes, and hemodynamic variables.

DESIGN

Twenty-three patients were randomly assigned to perform both walking tests on two different occasions. Total distance walked (DW), time of pain onset (PO), and time of limiting claudicating symptom (TLS) were analyzed.

RESULTS

The reliability coefficients (ICC) generated with the 6MW for DW, PO, and TLS were 0.84, 0.81, and 0.63, respectively, and the coefficients of variation (CV) across trials were 18, 31.8, and 20.3%, respectively. With the SWT, the ICCs were 0.95, 0.72, and 0.90 for each variable, respectively, whereas the CV was 10.9% for DW, 26.8% for PO, and 9.1% for TLS. There was a significant correlation between DW and double product with the SWT (r=0.51, P=0.01), but there was no correlation with the 6MW.

CONCLUSION

Both the 6MW and the SWT are reliable walking tests for claudicant patients. However, the reliability coefficients obtained with the SWT are higher, the measurements are less variable, and there were better associations between this walking test and hemodynamic variables.

High-Energy Phosphate Metabolism During Calf Ergometry in Patients With Isolated Aorto-Iliac Artery Stenoses

OBJECTIVES

Patients with peripheral arterial disease (PAD) and aorto-iliac atherosclerotic lesions suffer from a broad range of complaints, such as pain at the hip, the thigh, and calf claudication. The purpose of this study was to investigate the high-energy metabolism in the calf muscle of patients with PAD with isolated aorto-iliac stenoses during incremental plantar flexion exercise.

MATERIALS AND METHODS

Using a 1.5 T whole-body magnetic resonance (MR) scanner, 12 patients with PAD with uni- or bilateral aorto-iliac atherosclerotic lesions and 10 healthy male controls underwent serial phosphor-31 MR spectroscopy during incremental exercise at 2, 3, 4, and 5 W. The phosphocreatine (PCr) time constants were calculated for each increment and recovery using a monoexponential model. In the patient group, the run-off resistance was determined on MR angiograms. In both the patients and the controls, the ankle brachial pressure index was measured.

RESULTS

The diseased legs exhibited significantly increased PCr time constants during the second and the third workload increment at 3 and 4 W, but not during the first increment at 2 W and recovery compared with normal controls. Only 3 diseased legs succeeded the last increment at 5 W. We detected significant correlations between the ankle brachial pressure index scores and the PCr time constants when including both the diseased and the control legs. The diseased legs showed a significant correlation with the run-off resistance only during the first increment.

CONCLUSIONS

Our study shows that the impairment of muscle metabolism, expressed by prolonged PCr time constants, occurs with greater work intensities in patients with aorto-iliac disease compared with patients with multisegmental PAD, as recently published, whereas our patients collective exhibited normal PCr recovery time constants. Our findings may help to understand variability of clinical symptoms in aorto-iliac PAD.

The PADHOC Device is a Better Guide to the Actual Incapacity Suffered by Claudicants than the Gold Standard Constant Load Treadmill Test

BACKGROUND

The Constant Load Treadmill Test (CLTT) is currently the primary method used to measure walking impairment in patients with peripheral vascular disease. The aim of this study was to compare the CLTT and PADHOC device as assessments of walking impairment.

METHODS

55 patients with intermittent claudication underwent a CLTT and a Double Physiological Walking Test (DPWT) using the PADHOC device. Health-related quality of life was measured using the Short Form 36 and the Claudication Scale.

RESULTS

The initial claudication and maximum walking distance from the first part of the DPWT showed the best correlation with domains of pain and physical function.

CONCLUSIONS

The DPWT is more representative of the functional incapacity experienced by patients with intermittent claudication. We believe that the PADHOC is a suitable alternative to the CLTT in the assessment of this patient group.

High-energy phosphate metabolism during incremental calf exercise in patients with unilaterally symptomatic peripheral arterial disease measured by phosphor 31 magnetic resonance spectroscopy

BACKGROUND

The treadmill exercise test is the most important examination of the functional ability of patients with intermittent claudication or leg pain during exercise, but it does not provide any metabolic information in the calf muscle. The purpose of this study was to investigate the high-energy metabolism in the calf muscle during incremental progressive plantar flexion exercise of a selected peripheral arterial disease (PAD) patient group.

METHODS

Using a 1.5-T whole-body magnetic resonance scanner, 17 male patients with PAD who had 1 symptomatic and 1 asymptomatic leg and 9 healthy male controls underwent serial phosphor 31 (31P) magnetic resonance spectroscopy during incremental exercise at 2, 3, 4, and 5 W. Furthermore, magnetic resonance angiography was performed, and the ankle-brachial pressure index was determined in the patient group. The runoff resistance (ROR) was separately assessed in each patient's leg.

RESULTS

The symptomatic legs exhibited significantly increased phosphocreatine (PCr) time constants during the first three workload increments (2-4 W) and the recovery phase compared with the asymptomatic legs and the normal controls. Only two symptomatic legs reached the last increment at 5 W. Compared with the normal controls, the asymptomatic legs showed significantly increased PCr time constants only at 5 W. In the patient group, we detected significant correlations between the PCr time constants and the ROR, as well as the ankle-brachial pressure index. Moreover, the symptomatic legs presented significantly lower PCr levels and pH values at the end of exercise compared with the asymptomatic and control legs.

CONCLUSIONS

Our study shows that muscle function in PAD patients can be objectively quantified with the help of 31P magnetic resonance spectroscopy and correlates significantly with hemodynamic parameters such as ROR and ankle-brachial pressure index. Consequently, 31P magnetic resonance spectroscopy seems to be a useful method to monitor the muscle function of PAD patients for evaluation of established therapies or new therapeutic strategies during research trials.

High-energy phosphate metabolism in the calf muscle during moderate isotonic exercise under different degrees of cuff compression: A phosphorus 31 magnetic resonance spectroscopy study

BACKGROUND

The purpose of this study was to investigate phosphocreatine (PCr) and inorganic phosphate levels as well as pH changes in exercising muscle at a workload of 4.5 W under progressive cuff stenoses, whereby the flow reduction due to cuff compression was quantified by flow-sensitive magnetic resonance imaging.

METHODS

By using a whole-body 1.5-T magnetic resonance scanner and an exercise bench, serial phosphorus 31 (31P) magnetic resonance spectroscopy with a time resolution of 30 seconds was performed in 10 healthy men. Percentage changes in PCr, inorganic phosphate (Pi), and pH were statistically evaluated in comparison with baseline. The exercise protocol was characterized by a constant workload level of 4.5 W. Ischemic conditions were achieved by a cuff that was placed at the upper leg. Consecutively, increments of 0, 60, 90, 120, and 150 mm Hg were applied. Each increment lasted for 3 minutes. The following rest period was 10 minutes.

RESULTS

Blood flow increased significantly immediately after the onset of muscle exercise. No significant changes in blood flow were detected as long as the air pressure of the pneumatic cuff was 60 to 90 mm Hg. Significant reductions in blood flow were observed immediately after inflation of the cuff to 120 and 150 mm Hg. PCr passed into a steady state during the first increment with 0 mm Hg and showed no substantial changes during the increment with 60, 90, and 120 mm Hg. PCr hydrolysis seemed progressive during the 150-mm Hg increment. Pi passed into a plateau level at the onset of exercise and increased significantly at the increment of 150 mm Hg. The pH turned into a steady state with no significant changes during the increments up to 120 mm Hg. At 150 mm Hg, pH decreased progressively. PCr levels at the end of the 150-mm Hg increment correlated significantly and moderately with the reduction in blood flow.

CONCLUSIONS

Our study shows that the ischemic condition during constant muscle exercise is clearly characterized by PCr and Pi kinetics, as well as by pH changes. The correlation between the degree of blood flow reduction and PCr levels in the exercising muscle groups, which are supplied by the stenosed arteries, is the first essential of using 31P magnetic resonance spectroscopy in the assessment of the effect of arterial stenoses on muscle function in claudicants.

Treadmill versus shuttle walk tests of walking ability in intermittent claudication

PURPOSE

To compare treadmill and shuttle walk tests for assessing functional capacity in patients with intermittent claudication, with respect to test-retest reliability, cardiovascular responses, and patient preferences.

METHODS

Patients with stable intermittent claudication (N = 55, ages 52-85 yr, median age 68 yr) were recruited from the Sheffield Vascular Institute at the Northern General Hospital, Sheffield, UK. Each patient performed an incremental shuttle walk test, a constant-pace shuttle walk test, and a standardized treadmill test (3.2 km x h(-1), 12% gradient), each on three occasions. The incremental shuttle walk began at 3 km x h(-1) and increased by 0.5 km x h(-1) every minute, whereas the constant-pace shuttle walk was performed at the fixed pace of 4 km x h(-1). Claudication distance (CD), maximum walking distance (MWD), heart rate (HR), and blood pressure were assessed in each testing session. The patients also completed a test preference questionnaire.

RESULTS

CD and MWD for both shuttle walks were greater than the corresponding walking distances achieved in the treadmill test (P < 0.001). Average coefficients of variation for repeated incremental shuttle walk, constant-pace shuttle walk, and treadmill tests were 15.9%, 21.1%, and 18.7%, respectively, for MWD, corresponding to average intraclass correlation coefficients of 0.87, 0.82, and 0.87. Treadmill walking evoked greater increases in HR and blood pressure (P < 0.001), and fewer patients expressed a preference for it (24 vs 43% for shuttle walking).

CONCLUSION

These findings indicated that shuttle walk testing exhibits similar test-retest reliability as treadmill testing, but that it evoked a lower level of cardiovascular stress and is preferred to treadmill testing by a large proportion of patients.

Haemodynamic limitations and exercise performance in peripheral arterial disease

It has been frequently argued that haemodynamic limitations are poor predictors of exercise performance in people with peripheral arterial disease (PAD) and intermittent claudication. This review has tried to address this argument through a review of published data that appears to support or counterbalance it, brief consideration of some of the methodological limitations associated with these data, as well as some other considerations. The main argument rests primarily upon data about the resting ankle-brachial index (ABI) and/or blood flow after calf exercise or an ischaemic challenge; whereas the counter argument rests mainly on data about blood flow during walking or cyding exercise. Consideration of the limitations of all methods suggests that the measurement of blood flow during exercise has the greatest value in explaining differences in exercise performance amongst claudicants; whereas the other methods are relatively limited in their explanatory value. This strengthens the counter argument and undermines the main argument proposed by others. Consequently, asserting that haemodynamic limitations are poor predictors of exercise performance in claudicants is not justified in light of available evidence.

A new device for the measurement of disease severity in patients with intermittent claudication

OBJECTIVES

To assess a new method of determining functional impairment in patients with intermittent claudication, the Double Physiological Walking Test (DPWT) using the PADHOC (Peripheral Arterial Disease Holter Control) device, against a standard treadmill test.

DESIGN

Patients with intermittent claudication presenting to the department were considered for both the DPWT and a standard treadmill test.

METHODS

initial claudicating distance, maximal walking distance and speed of walking were determined for both parts of the DPWT. Initial claudicating distance and maximal walking distance were determined from the treadmill test. Comparisons were made between the treadmill test and the DPWT.

RESULTS

The treadmill test was unable to be performed in 22% of patients due to defined contraindications. There were strong correlations in both walking distances and disease severity when comparing the DPWT and the treadmill test. Patients in whom the treadmill test was contraindicated had significantly shorter walking distances on the DPWT than those who were able to complete a treadmill walking test.

CONCLUSIONS

The DPWT correlates strongly with walking distances obtained from a standard treadmill test. However, the PADHOC can be used in a number of differing locations and settings as well as in patients in whom a treadmill test is contraindicated. It therefore has a role to play in the initial assessment of patients presenting with intermittent claudication.