Thromboxane and neutrophil changes following intermittent claudication suggest ischaemia-reperfusion injury

Comparison of Cilostazol and Naftidrofuryl in an Experimental Acute Ischemia-Reperfusion Model

INTRODUCTION

Naftidrofuryl and cilostazol are drugs with proven efficacy in the treatment of claudication in peripheral vascular disease. In this experimental study, we evaluated the effects of naftidrofuryl and cilostazol in ischemia-reperfusion (IR) injury on various tissues.

MATERIALS AND METHODS

40 male albino Wistar rats (8-12 weeks old, 250-350 g.) are randomly divided into 4 groups: Control (Group 1), sham (group 2), cilostazol pre-treatment (group 3), naftidrofuryl pre-treatment (group 4). During 21 days placebo is given to group 2, 12 mg/kg/day cilostazol is given to group 3, 50 mg/kg/day naftidrofuryl is given to group 4 orally. Ischemia and reperfusion are induced at the lower hind limb in Groups 2, 3 and 4. Ischemic muscle, kidney, liver, heart, brain and blood samples are obtained. The total antioxidant capacity, oxidant levels and oxidative stress index are studied for each group.

RESULTS

Both drugs have protective effects of remote organ injury following IR. Systemic effects are similar to each other, both have protective effects of IR injury. It showed no statistical significance in the total antioxidant capacity. Total oxidant levels are significantly affected by cilostazol in the heart (p < 0.01) and by naftidrofuryl in the liver (p < 0.01). The effect on oxidative stress was only significant with cilostazol on the heart (p < 0.01).

CONCLUSION

Cilostazol and naftidrofuryl had beneficial effects in all tissues against tissue damage caused by IR injury. In ischemic muscle, kidney and heart cilostazol had improved outcomes comparing to naftidrofuryl. Naftidrofuryl had benefits over cilostazol in liver tissue.

Challenges in recruitment and adherence to a randomized clinical trial in Brazil on the effects of transcutaneous nervous electrical stimulation on individuals with peripheral arterial disease: A feasibility study

OBJECTIVE

Describe the feasibility, barriers during the recruitment and intervention period, recruitment rate (success and efficiency), and the level of participation and adherence in the randomized clinical trial to verify the effects of transcutaneous electrical nerve stimulation (TENS) for the symptoms of intermittent claudication (IC) and its repercussions on functional capacity, cardiorespiratory fitness and cardiovascular autonomic function in individuals with sta II Fontaine classification, residing in Brazil.

DESIGN

Prospective, double-blind, randomized clinical trial.

SETTING

Level secondary.

PARTICIPANTS

A total of 63 participants were screened, of which 12.6% were included. Eight individuals with peripheral arterial disease (PAD) and IC underwent a protocol that lasted 8 weeks.

INTERVENTIONS

The experimental group received 45 minutes TENS 10 Hz, followed by 30 minutes of aerobic exercise, and the control group received a placebo TENS also followed by 30 minutes of exercise. Incremental walking test, gait impairment questionnaire, treadmill test, heart rate variability, and 4-second test were applied, considering adherence, success, and efficiency.

RESULTS

The most efficient recruitment sources were as follows: 1) referral by physician and 2) referral by a physiotherapist. Out of 63 participants, 8 (12.6%) were included in the clinical trial. Participants were excluded due to the following reasons: not meeting the criteria (41 participants (65%)), locomotion (6 participants (9.5%)), transportation (5 participants (7.9%)), work release (1 participant (1.6%)), and interest (2 participants (3.2%)). The overall participation was 99 participants (51.6%) in a total of 192 sessions offered.

CONCLUSION

It was not possible to succeed in recruitment and adherence rates. The results of this clinical trial reinforce that PAD is neglected, and strategies including a multidisciplinary approach with the effective participation of nursing, physiotherapy, medicine, and nutrition professionals, are necessary to optimize care for individuals with PAD need to be strengthened. Brazilian Registry of Clinical Trials (RBR-8RTZFN).

Intermittent Claudication in Physiotherapists' Practice

Intermittent claudication is a symptom of atherosclerosis of the lower limbs (peripheral arterial disease (PAD)) and is characterized by pain and cramps of lower limb muscles during exercise. Claudication leads to a reduction in physical activity of patients. PAD is a systemic disease. Atherosclerotic lesions located in the arteries of the lower limbs not only pose the risk of the ischemic limb loss, but above all, they are an important prognostic factor. Patients with claudication are at significant risk of cardiovascular complications such as infarcts or strokes. Comprehensive rehabilitation of patients with intermittent claudication based on the current TASC II (Inter-Society Consensus for the Management of Peripheral Arterial Disease) guidelines, ESC (European Society of Cardiology) guidelines, and AHA (American Heart Association) guidelines includes supervised treadmill training, training on a bicycle ergometer, Nordic Walking, resistance exercises of lower limb muscles, and exercises of upper limbs. A trained, educated, and motivated patient has a chance to improve life quality as well as life expectancy.

Prevention of post-traumatic clinical capillary leak syndrome

Systemic capillary leak is an early feature of the inflammatory response to localized injury, and is proportional to the severity of the inflammatory insult. Loss of local control of inflammation leads to an exaggerated systemic inflammatory response known as systemic inflammatory response syndrome (SIRS). SIRS is associated with multiple organ failure and death when there is failure to maintain homeostasis.

Whilst the application of molecular biology and recombinant techniques have produced major advances in our understanding of the mediation of the inflammatory response, there is no agent currently available which will prevent SIRS and reduce the incidence of post-traumatic multiple organ failure. In the meantime, a more practical approach to the avoidance of SIRS and its attendant capillary leak syndrome is to attempt to reduce the deleterious effects of interstitial oedema by tailoring treatment to the rapid changes in capillary permeability.

Endovascular treatment of lower extremity arteries is associated with an improved outcome in diabetic patients affected by intermittent claudication

BACKGROUND

Lower extremity peripheral arterial disease (LE-PAD) is a highly prevalent condition among diabetic patients, associated with reduced walking capacity and a high incidence of cardiovascular events. Endovascular revascularization of lower extremities arteries improves walking performance and quality of life of diabetic patients affected by intermittent claudication, but few studies evaluated the impact of revascularization on cardiovascular outcome in this high-risk population. Accordingly, in the present study we evaluated if leg-ischemia resolution by effective lower limbs percutaneous revascularization can also impact cardiovascular outcome in a homogeneous group of diabetic patients affected by intermittent claudication.

METHODS

236 diabetic patients affected by LE-PAD at stage II of Fontaine's classification, with ankle/brachial index ≤ 0.90 and one or more hemodynamically significant stenosis in at least one artery of the ileo-femoro-popliteal axis were enrolled in the study. According to the Trans-Atlantic Inter Society Consensus II recommendations, 123 (52.1%) underwent percutaneous transluminal angioplasty (PTA group), while 113 (47.9%) underwent conservative medical therapy only (MT group). The incidence of major cardiovascular events (cardiovascular death, myocardial infarction, ischemic stroke, coronary or carotid revascularization) was prospectively analyzed with Kaplan-Meier curves and the risk of developing a cardiovascular event calculated by Cox analyses.

RESULTS

No baseline difference in cardiovascular risk factors were observed between the PTA and MT groups, except for a lower prevalence of males in PTA group (74.8% vs. 85.8%, p=0.034). Furthermore, patients in the PTA group showed a worse walking capacity as expressed by maximum walking distance (108.7 ± 300.9 vs 378.4 ± 552.3 meters, p<0.001). During a median follow-up of 20 months (12.0-29.0), the incidence of cardiovascular events was markedly lower in patients in the PTA group with respect to patients in the MT group (7.3% vs. 22.1%, p=0.001), and patients of the MT group had at Cox analysis a 3.9 increased risk with respect to PTA group, after adjustment for potential confounding factors (95% CI 1.1-15.3, p=0.049).

CONCLUSIONS

The present study shows that lower limbs revascularization of diabetic patients affected by intermittent claudication, in addition to improve walking performance, is associated with a reduction in the incidence of future major cardiovascular events.

Effects of successful percutaneous lower extremity revascularization on cardiovascular outcome in patients with peripheral arterial disease

BACKGROUND

Lower extremity peripheral arterial disease (LE-PAD) reduces walking capacity and is associated with an increased cardiovascular risk. Endovascular revascularization of LE-PAD improves walking performance and quality of life. In the present study, we determined whether successful lower limbs revascularization also impacts cardiovascular outcome in LE-PAD patients.

METHODS

479 consecutive LE-PAD patients at stage II of Fontaine's classification, with ankle/brachial index ≤ 0.90 and one or more stenosis >50% in at least one leg artery, were enrolled in the study. According to the Trans-Atlantic Inter Society Consensus II recommendations, 264 (55.1%) underwent percutaneous lower extremity angioplasty (PTA group), while 215 (44.9%) were managed with conservative therapy (MT group). The incidence of major cardiovascular events (including cardiovascular death, myocardial infarction, ischemic stroke, coronary and carotid revascularizations) was prospectively analyzed by Kaplan-Meier curves. Crude and adjusted HRs (95% CI) of developing a cardiovascular event were calculated by Cox analysis.

RESULTS

No baseline differences were observed among the groups, except for a lower maximum walking distance in the PTA group. During a median follow-up of 21 months (12.0-29.0), the incidence of cardiovascular events was markedly lower in PTA compared to MT patients (6.4% vs. 16.3%; p=0.003), and patients in the MT group showed a 4.1-fold increased cardiovascular risk compared to patients in the PTA group, after adjustment for potential confounders (95% CI 1.22-13.57, p=0.023).

CONCLUSIONS

This study shows that successful revascularization of LE-PAD patients affected by intermittent claudication, in addition to improving functional status, reduces the occurrence of future major cardiovascular events.

Treadmill exercise in claudicants on aspirin results in improved antioxidant status but only minimal platelet activation

The consequence of exercise on platelets remains controversial and adverse effects may result from repeated ischaemia reperfusion injury. We investigated platelet activation (platelet P-selectin (PS), and activated glycoprotein (Gp) IIb/IIIa), platelet-monocyte aggregates (PMA) and total plasma antioxidant status (TPAS) in claudicants after exercise. Twenty claudicants, taking 75 mg of aspirin daily, were subjected to repeated treadmill testing (3 km/h, 10% inclination). Blood was sampled before and after exercise. Activated GpIIb/IIIa, PS and PMA were quantified with flow cytometry. TPAS was quantified using a decolourisation assay. Percent positive cells for PS (pre-exercise 3.76% vs. 40 min post-exercise 4.10%; P < 0.05) and platelet-monocyte aggregates (pre-exercise: 25.31% vs. 40 min post-exercise 26.99%; P < 0.05) were significantly higher after exercise. Relative median fluorescence (RMF) for activated GpIIb/IIIa was significantly higher 40 min after exercise (pre-exercise: 3.04 vs. 40 min post-exercise: 4.01; P < 0.05). TPAS was significantly higher post-exercise (pre-exercise: 1.31 mmol/l vs. 1 min post-exercise: 1.40 mmol/l and 40 min post-exercise: 1.38 mmol/l; P < 0.01). Following moderate exercise, 'aspirin treated claudicants' show marginal platelet activation, PMA formation and a favourable improvement in antioxidant status. Further studies are required to assess the effect of additional antiplatelet agents and the significance of platelet-monocyte interactions. The possibility that aspirin contributes to the TPAS changes following exercise needs to be investigated.

The effects of cilostazol on exercise-induced ischaemia-reperfusion injury in patients with peripheral arterial disease

OBJECTIVES

Cilostazol improves walking distance in peripheral arterial disease (PAD) patients. The study objectives were to assess the effects of cilostazol on walking distance, followed by the additional assessment of cilostazol on exercise-induced ischaemia-reperfusion injury in such patients.

METHODS

PAD patients were prospectively recruited to a double-blinded, placebo-controlled trial. Patients were randomised to receive either cilostazol 100mg or placebo twice a day. The primary end-point was an improvement in walking distance. Secondary end-points included the assessment of oxygen-derived free-radical generation, antioxidant consumption and other markers of the inflammatory cascade. Initial and absolute claudication distances (ICDs and ACDs, respectively) were measured on a treadmill. Inflammatory response was assessed before and 30 min post-exercise by measuring lipid hydroperoxide, ascorbate, alpha-tocopherol, beta-carotene, P-selectin, intracellular and vascular cell-adhesion molecules (I-CAM and V-CAM), thromboxane B(2) (TXB(2)), interleukin-6, interleukin-10, high-sensitive C-reactive protein (hsCRP), albumin-creatinine ratio (ACR) and urinary levels of p75TNF receptor. All tests were performed at baseline and 6 and 24 weeks.

RESULTS

One hundred and six PAD patients (of whom 73 were males) were recruited and successfully randomised from December 2004 to January 2006. Patients who received cilostazol demonstrated a more significant improvement in the mean percentage change from baseline in ACD (77.2% vs. 26.6% at 6 weeks, p=0.026 and 161.7% vs. 79.0% at 24 weeks, p=0.048) as compared to the placebo. Cilostazol reduced lipid hydroperoxide levels compared to a placebo-related increase before and after exercise (6 weeks: pre-exercise: -11.8% vs. +5.8%, p=0.003 and post-exercise: -12.3% vs. +13.9%, p=0.007 and 24 weeks: pre-exercise -15.5% vs. +12.0%, p=0.025 and post-exercise: -9.2% vs. +1.9%, p=0.028). beta-Carotene levels were significantly increased in the cilostazol group, compared to placebo, before exercise at 6 and 24 weeks (6 weeks: 34.5% vs. -7.4%, p=0.028; 24 weeks: 34.3% vs. 17.7%, p=0.048). Cilostazol also significantly reduced P-selectin, I-CAM and V-CAM levels at 24 weeks as compared to baseline (p<0.05). There was no difference between treatment groups for ascorbate, alpha-tocopherol, interleukin-6 and -10, hsCRP and p75TNF receptor levels.

CONCLUSIONS

Cilostazol significantly improves ACD, in addition to attenuating exercise-induced ischaemia-reperfusion injury, in PAD patients.

Measurement of ischaemia-reperfusion in patients with intermittent claudication using NMR-based metabonomics

Intermittent claudication has proved to be a good in vivo model for ischaemia-reperfusion. For assessment of ischaemia-reperfusion damage, the known biochemical markers all have disadvantages with respect to sensitivity and interference with other physiological events. In this work, we studied the metabolic effects of ischaemia-reperfusion in patients with intermittent claudication, and the effects of vitamin C and E intervention, using both traditional biochemical measurements and 1H-NMR-based metabonomics on urine and plasma. The 1H-NMR spectra were subjected to multivariate modelling using principal components discriminant analysis, and the observed clusters were validated using joint deployment of univariate analysis of variance and Tukey-Kramer honestly significant difference (HSD) testing. The study involved 14 patients with intermittent claudication and three healthy volunteers, who were monitored during a walking test, before and after a vitamin C/E intervention, and after a washout period. The effect of exercise was only observable for a limited number of biochemical markers, whereas 1H NMR revealed an effect in line with anaerobic ATP production via glycolysis in exercising (ischaemic) muscle of the claudicants. Thus, the beneficial effect of vitamins C and E in claudicants was more pronounced when observed by metabonomics than by traditional biochemical markers. The main effect was more rapid recovery from exercise to resting state metabolism. Furthermore, after intervention, claudicants tended to have lower concentrations of lactate and glucose and several other citric acid cycle metabolites, whereas acetoacetate was increased. The observed metabolic changes in the plasma suggest that intake of vitamin C/E leads to increased muscle oxidative metabolism.

Effects of warm-up on exercise capacity, platelet activation and platelet-leucocyte aggregation in patients with claudication

BACKGROUND

The effects of exercise and warm-up were investigated in patients with claudication.

METHODS

This case-control crossover study involved two treadmill exercise tests, one preceded by a warm-up. Exercise continued until maximal leg pain (patients with claudication) or exhaustion (controls). Blood was taken before, and 5 and 60 min after exercise for flow cytometric analysis of platelet activation and platelet-leucocyte aggregation.

RESULTS

Both cohorts (eight patients with claudication of median age 63 years and eight healthy controls of median age 63.5 years) demonstrated improvement in exercise capacity after warm-up (13.1 per cent, P = 0.012 and 15.6 per cent, P = 0.008 respectively). Platelet activation increased after exercise in patients with claudication (fibrinogen binding: 1.11 per cent before exercise versus 2.63 per cent after exercise, P = 0.008; P-selectin: 0.68 versus 1.11 per cent, P = 0.028). Neither agonist stimulation nor warm-up altered this trend. Platelet-leucocyte (PLA) and platelet-neutrophil (PNA) aggregation were similarly increased immediately after exercise in patients with claudication (PLA: 7.6 versus 13.0 per cent, P = 0.004; PNA: 6.8 versus 10.2 per cent, P = 0.012). These remained high 60 min after exercise only in patients with claudication, but recovered to baseline levels when preceded by warm-up. Warm-up significantly desensitized PNA after stimulation with 10 micromol/l adenosine 5'-diphosphate at all time points.

CONCLUSION

Warm-up increased the exercise capacity of patients with claudication. Exercise induced a thromboinflammatory response, with PLA and PNA persistently increased after 60 min in patients with claudication, an effect diminished after warm-up.

High circulating levels of cytokines (IL-6 and TNFalpha), adhesion molecules (VCAM-1 and ICAM-1) and selectins in patients with peripheral arterial disease at rest and after a treadmill test

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis that is associated with systemic inflammation. The aim of our study was to assess whether plasma markers of inflammation increased after exercise in patients with PAD. The study was conducted on two groups of 20 subjects each: one group (mean age 68.4 +/- 5.09 years) was affected by PAD with claudication, while the other group consisted of healthy controls (66.9 +/- 6.1 years). Concentrations of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNFalpha) were determined in plasma, in supernatants and in cells stimulated with 1 mg lipopolysaccharide in all patients. E-selectin (ES), L-selectin (LS) and P-selectin (PS) concentrations and plasma concentrations of VCAM-1 and ICAM-1 were also determined. All determinations were performed in patients at rest and after the treadmill exercise. Resting values of soluble mediators were greater in PAD patients than in controls. They increased in both groups after the treadmill test, even if post-treadmill concentrations were significantly higher in PAD patients (PAD p < 0.001 or 0.0001, controls p < 0.05 or 0.001). These results confirm that white blood cell activation is characteristic of systemic atherosclerosis and that these inflammation markers increase in conditions of hemodynamic stress.

Oxidative damage to skeletal muscle following an acute bout of contractile claudication

The purpose of this study was to determine the extent and sources of oxidative stress within skeletal muscle following an acute bout of contractile claudication. Twenty-four hours after unilateral ligation of the femoral artery, rat hind limbs were stimulated in vivo for 30 min, and force production measured. One-hour post-stimulation, animals were sacrificed and soleus and gastrocnemius muscles removed. There was significant reduction in force in the control limb (sham ligated/stimulated (SS)), while force in the ligated limb (ligated/stimulated (LS)) was reduced by 72%. There was an increase in skeletal muscle lipid hydroperoxides (53 and 47%) and protein carbonyls (57 and 54%) in the soleus and gastrocnemius muscles, respectively, and the muscle wet/dry weight ratio was increased in the gastrocnemius muscles. Total glutathione (GHS) was reduced, while xanthine oxidase (XO) activity and neutrophil levels were increased, in LS compared to SS in both soleus and gastrocnemius muscles. These data suggest that an acute bout of contractile claudication causes significant oxidative damage and edema to skeletal muscle. This is associated with both an increase in the activity of the radical-producing enzyme xanthine oxidase and an increase in activated neutrophils.

Vitamin C prevents endothelial dysfunction induced by acute exercise in patients with intermittent claudication

In patients with intermittent claudication, exercise is associated with a marked increase in oxidative stress, likely responsible for systemic endothelial perturbation. In 31 claudicant patients, we assessed the effect of vitamin C administration on the acute changes induced by maximal and submaximal exercise in endothelium-dependent, flow-mediated dilation (FMD), and in plasma levels of thiobarbituric acid-reactive substances (TBARS) and soluble intercellular adhesion molecule-1 (sICAM-1). In 16 claudicants, maximal exercise reduced FMD (from 8.5+/-0.9 to 3.7+/-0.8%, P<0.01), and increased plasma levels of TBARS (from 1.93+/-0.06 to 2.22+/-0.1 nmol/ml, P<0.02) and of sICAM-1 (from 282+/-17 to 323+/-19 ng/ml, P<0.01). In eight of these patients, randomized to vitamin C, exercise-induced changes in FMD and biochemistry were abolished. This beneficial effect was not observed in the eight patients randomized to saline. In 15 patients, who walked until the onset of claudication pain (submaximal exercise), and in ten control subjects, who performed maximal exercise, no changes were observed with exercise. Thus, in claudicants, vitamin C prevents the acute, systemic impairment in endothelial function induced by maximal exercise. This finding provides a rationale for trials investigating antioxidant therapy and cardiovascular risk in patients with intermittent claudication.

Exercise training reduces the acute inflammatory response associated with claudication

BACKGROUND

recent research has shown that episodes of claudication may be associated with a systemic inflammatory response that causes injury to the vascular endothelium. As claudicants are often directed to undertake regular walking exercises there has been a concern that this may accelerate endothelial injury.

AIMS

the aim of our study was to assess the baseline markers of ischaemia-reperfusion injury (IRI) in claudicants and controls after acute treadmill exercise and to then examine the effect of a 3 month supervised exercise-training programme, on these markers, in the claudicant group.

METHODS

forty-six claudicants and 22 age-matched controls undertook acute treadmill exercise. Neutrophil activation, degranulation, free radical damage and antioxidants were measured (by flow cytometry, ELISA, and chemiluminescence) at rest and at 5, 30 and 60 min post-exercise. Claudicants were then recruited into an intensive 3 month supervised exercise programme (SEP) after which the same parameters of IRI were reassessed at different time points, at 3 and 6 months.

RESULTS

resting markers of IRI were similar in both groups. Exercise had no effect on the control group. Immediately after exercise, claudicants developed significant neutrophil activation and degranulation with free radical damage. This effect decreased sequentially after 3 months of exercise training.

CONCLUSION

this study for the first time demonstrates that the exercise training of claudicants is beneficial, not only in terms of improving their walking distance, but also by decreasing the injurious effects of IRI that occur during claudication. Exercise training should be an essential part of the medical management of the majority of claudicants.

The systemic effects of intermittent claudication are reversed by angioplasty

INTRODUCTION

exercise in patients with intermittent claudication causes systemic effects, the consequences of which are unknown. This study investigates whether successful PTA reverses the systemic effects.

PATIENTS AND METHODS

ten patients with IC were recruited prior to PTA. Having emptied their bladders and rested for 1 h, pre-exercise blood and urine samples were collected. Patients underwent treadmill exercise to maximum walking time and blood samples were collected at 10, 20 and 30 min. A second urine sample was collected at 60 min. Total antioxidant capacity (TAC) and von Willebrands Factor (vWF) were measured in blood and albumin/creatinine ratio (ACR) and retinol binding protein/creatinine ratio (RBP/Cr) in urine. Patients were recalled 2 weeks after successful angioplasty and the protocol repeated. Following PTA patients walked for a maximum of 5 min.

RESULTS

there was no significant change in vWF. Exercise in claudicants induced a significant increase in median ACR (pre/post exercise=0.85 p =0.03) and in median RBP/Cr (pre/post exercise=1.8 p =0.04). These changes were no longer evident after successful PTA. TAC was significantly different before and after angioplasty at all time intervals.

CONCLUSION

successful PTA reverses glomerular effects of exercise in claudicants. Future work should investigate the use of PTA in conjunction with exercise in the treatment of peripheral vascular disease.

Macrovascular disease aetiology and diabetic foot ulceration

This is the first of two literature reviews exploring the role of large and small vessel disease in the development of diabetic foot lesions. It describes the aetiology of macrovascular disease and the contentious issues surrounding this mechanism of tissue damage in people with diabetes.

Antioxidants reduce oxidative stress in claudicants

BACKGROUND

Low-grade ischemia-reperfusion in claudicants leads to damage of local tissues and remote organs. Since this damage is partly caused by oxygen-derived free radicals (ODFR), scavenging these ODFR could reduce the local and remote injury.

METHODS

Using a new method by which a free radical reaction product (ortho-APOH) of the exogenous marker antipyrine is measured to quantify the oxidative stress, 16 stable claudicants performed a standard walking test before and after administration of vitamin E (200 mg) and vitamin C (500 mg) daily for 4 weeks.

FINDINGS

Ortho-APOH was significantly increased during the reperfusion period (P = 0.026) before administration of the vitamins. After 4 weeks of vitamin supplementation no rise was found in the reperfusion period. Malondialdehyde showed no changes in either group.

INTERPRETATION

These findings indicate that administering extra antioxidants to claudicants reduces oxidative stress in these patients. This may also have an effect on the remote ischemia-reperfusion damage and reduce cardiovascular morbidity in this group.

Intestinal permeability is increased in patients with intermittent claudication

PURPOSE

Intermittent claudication can be regarded as repeated ischemia reperfusion injury, which can induce a generalized increase in vascular permeability, including in intestine. The lactulose mannitol test (L/M test) was performed in patients with intermittent claudication to evaluate the change in intestinal permeability when they were forced to walk.

METHODS

The L/M test was performed in 11 patients with intermittent claudication and 11 control subjects without intermittent claudication. The test was performed at rest and after exercise. Patients walked on a treadmill until they stopped because of pain. The control subjects were forced to walk as far as 200 m on a treadmill. The L/M test was repeated in the patients after successful arterial reconstruction. Then the patients were instructed to walk the same distance at the same speed as they had before surgery.

RESULTS

In patients, the mean L/M ratio after exercise was significantly higher than the mean L/M ratio when they were at rest (0.068 +/- 0.053 vs 0.022 +/- 0.009, P <.05). In control subjects, however, no significant difference was observed between the mean L/M ratios after exercise and at rest. The mean L/M ratio after exercise, decreased from 0.068 +/- 0.053 to 0.018 +/- 0. 016 after successful arterial reconstruction (P <.05) in patients.

CONCLUSION

Intestinal permeability, determined by means of the L/M test, significantly increased in patients with intermittent claudication after exercise, and it diminished after arterial reconstruction. The L/M test is, consequently, a new noninvasive method to reflect ischemia in lower limbs during exercise.

Exercise training and peripheral vascular disease

BACKGROUND

Conservative management is advocated as a treatment of choice for patients with intermittent claudication. This is a review of the mechanisms behind the improvement following an exercise rehabilitation programme.

METHODS

All Medline articles from the National Library of Medicine, USA containing the text words 'claudication' or 'peripheral vascular disease' and 'exercise' were reviewed. Cross-referencing from relevant articles was carried out.

RESULTS AND CONCLUSION

The poor physical status of a patient with intermittent claudication is not solely due to a reduction in blood flow to the lower limbs; associated factors, such as metabolic inefficiency, poor cardiorespiratory reserve and exercise-induced inflammation contribute. An exercise programme frequently improves both the physical aspect and quality of life, and the success of such exercise is multifactorial. An increase in the blood flow to the lower extremity is uncommon. Other factors, such as a redistribution of blood flow, changes in oxidative capacity of the skeletal muscles and greater utilization of oxygen, occur and the associated metabolic dysfunction of the skeletal muscles is rectified. Following exercise training, blood rheology improves and exercise-induced inflammation is ameliorated; cardiorespiratory status also benefits and the oxygen cost of exercise decreases.

Biochemical and inflammatory changes in the exercising claudicant

Intermittent claudication is an early manifestation of atherosclerosis in the leg. The prognosis for the claudicating limb is reasonably good, but patients have excess cardiovascular morbidity and mortality rates compared with a control population. Increasing evidence suggests that the calf pain experienced when walking followed by rest generates a low-grade inflammatory response. The cumulative effects of these individual events may have an adverse effect on the progression of atherosclerosis. A review of the literature was performed to identify studies measuring the exercise-induced inflammatory response in claudicants and to try to identify the role of cumulative inflammatory changes in the progression of atherosclerosis. The effect of exercise training on these markers is briefly explored. Walking until the onset of calf pain (ischaemia) followed by rest (reperfusion) results in the generation of oxygen-derived free radicals, neutrophil activation and a generalized increase in vascular permeability. Baseline levels of chronic inflammatory markers such as acute-phase proteins are elevated in claudicants compared with controls, suggesting that the transient acute inflammatory response has longer-term consequences. Therapeutic exercise training appears to lead to an attenuation of these inflammatory markers. Intermittent claudication can be considered as part of an inflammatory disease process. However, the concerns that exercise training might potentiate the vascular inflammatory response appear to be unjustified, although further work is needed to clarify this. Exercise training should therefore be considered as an important treatment option for claudication.

Exercise-induced neutrophil activation in claudicants: a physiological or pathological response to exhaustive exercise?

OBJECTIVES

To assess the effect of exhaustive exercise on neutrophil activation and degranulation in claudicants and controls. We investigated the hypothesis that neutrophil activation and degranulation are normal responses to exhaustive exercise in healthy patients.

DESIGN

This was a controlled experimental two-group study.

MATERIALS

Exercise was performed using a fixed workload treadmill test. Neutrophil activation was assessed by flow cytometry of whole blood labelled with anti-CD11b mouse IgG, and neutrophil degranulation in terms of plasma elastase measured by enzyme-linked immunosorbent assay.

METHODS

Twenty-eight claudicants with stage 1 chronic leg ischaemia, and 22 healthy controls were recruited. Blood and urine samples were collected before and after treadmill exercise. Claudicants exercised to their maximum walking distance, and controls at a higher "fatigue" workload for a maximum of 20 min.

RESULTS

Exercise produced a brief but significant neutrophilia in both groups. Neutrophil CD11b expression increased significantly after exercise only in the claudicants, and was associated with a significant rise in plasma neutrophil elastase. These indices remained unchanged in the control group at all time points despite exercise at a fatigue level.

CONCLUSION

The inflammatory response associated with exercise in claudicants is not simply a physiological response to exhaustive exercise.

The evidence for exercise-induced inflammation in intermittent claudication: should we encourage patients to stop walking?

OBJECTIVES

To review clinical and experimental evidence that exercise to the onset of calf pain in patients with intermittent claudication results in an inflammatory response, and to consider whether repeated inflammatory events induced by therapeutic exercise training may lead to progression of atherosclerosis.

METHODS

A literature search was performed to identify studies measuring biochemical markers of exercise-induced ischaemia-reperfusion injury in patients with intermittent claudication. Current theories of atherogenesis were reviewed and the use of acute-phase proteins as potential markers of vascular disease explored.

RESULTS

Exercise to the onset of calf pain results in an inflammatory response with free radical formation, neutrophil activation and systemic vascular endothelial damage. Acute-phase proteins such as C-reactive protein and serum amyloid A protein have exciting potential use as stable biochemical markers of disease in claudication.

CONCLUSIONS

Further studies are needed to determine the effect of long-term exercise training on exercise-induced inflammation in claudication. Early work suggests, in fact, that exercise attenuates this inflammatory response. If this were confirmed then it would support the clinical impression that exercise training is beneficial in terms of symptomatic improvement and cardiovascular health in patients with intermittent claudication.

Exercise training for intermittent claudication: does it adversely affect biochemical markers of the exercise-induced inflammatory response?

OBJECTIVES

To identify a stable biochemical marker of disease severity in patients with intermittent claudication and to use these findings to assess the effect of therapeutic exercise training.

DESIGN

Case-control study: prospective randomised-controlled trial of exercise training.

MATERIALS AND METHODS

Plasma fibrinogen, serum amyloid A protein (SAA), C-reactive protein (CRP) and urinary albumin-creatinine ratio (ACR) were measured in 67 claudicants and 15 controls. Twenty-two patients were randomised to supervised exercise training and 17 randomised to observation. Subjects were reviewed at 3, 6 and 12 months.

RESULTS

The median (interquartile range) baseline fibrinogen was 3.7 g/l (3.3-4.25) in claudicants and 3.5 g/l (2.9-3.95) in controls (p = 0.045); CRP was 4.7 mg/l (2.2-9.0) and 2.1 mg/l (1.0-2.8), respectively (p < 0.0001); SAA was 72 mg/l (35-132) and 30 mg/l (20-89) (p = 0.0009). Claudicants showed an increased urinary ACR following treadmill exercise (Wilcoxon, p < 0.0001) with no change in controls. Exercise training reduced SAA at 6 months, CRP at 3 months and progressively attenuated the post-exercise increase in ACR. No similar changes were found in controls.

CONCLUSIONS

Repetitive low-grade inflammatory events in claudicants lead to elevation of serum acute-phase proteins. Exercise training is associated with symptomatic improvement and reduction inflammatory markers. The concern that exercise has adverse systemic effects therefore seems to be unjustified.