Assessment of intermittent claudication by quantitation of exercise-induced microalbuminuria

Exercise training in intermittent claudication: Effects on antioxidant genes, inflammatory mediators and proangiogenic progenitor cells

Exercise training remains a therapy of choice in intermittent claudication (IC). However, too exhaustive exercise may cause ischaemic injury and inflammatory response. We tested the impact of three-month treadmill training and single treadmill exercise on antioxidant gene expressions, cytokine concentrations and number of marrow-derived proangiogenic progenitor cells (PPC) in the blood of IC patients. Blood samples of 12 patients were collected before and after training, before and 1, 3 and 6 hours after the single exercise. PPCs were analysed with flow cytometry, cytokine concentrations were checked with Milliplex MAP, while expression of mRNAs and miRNAs was evaluated with qRT-PCR. Treadmill training improved pain-free walking time (from 144 ± 44 seconds [s] to 311 ± 134 s, p=0.02) and maximum walking time (from 578 ± 293 s to 859 ± 423 s, p=0.01) in IC patients. Before, but not after training, the single treadmill exercise increased the number of circulating CD45dimCD34+CD133-KDR+ PPCs (p=0.048), decreased expression of HMOX1 (p=0.04) in circulating leukocytes, reduced tumour necrosis factor-α (p=0.03) and tended to elevate myeloperoxidase (p=0.06) concentrations in plasma. In contrast, total plasminogen activator inhibitor-1 was decreased by single exercise only after, but not before training (p=0.02). Both before and after training the single exercise decreased monocyte chemoattractant protein (MCP)-1 (p=0.006 and p=0.03) concentration and increased SOD1 (p=0.001 and p=0.01) expression. Patients after training had also less interleukin-6 (p=0.03), but more MCP-1 (p=0.04) in the blood. In conclusion, treadmill training improves walking performance of IC patients, attenuates the single exercise-induced changes in gene expressions or PPC mobilisation, but may also lead to higher production of some proinflammatory cytokines.

Microalbuminuria in non-diabetic patients with unstable angina/non ST-segment elevation myocardial infarction

BACKGROUND

Microalbuminuria (MAU) is defined as an urinary albumin excretion rate between 20-200 mg/l or 30-300 mg/day. It is a surrogate marker for endothelial dysfunction and is independently associated with atherosclerotis in diabetic and in non-diabetic patients. We assessed the prevalence of MAU in non-diabetic patients who presented with UA/NSTEMI and the relation of MAU to the severity of coronary artery disease in patients at a cardiac care center in Iraq.

METHODS

Seventy non-diabetic patients referred to the Iraqi Center for Heart Disease, Baghdad, between November 1st 2010 and June 1st 2011 with the diagnosis of UA/NSTEMI were included in this study. Physical examination, ECG and echocardiography were performed on all patients. TIMI ("Thrombolysis in Myocardial Infarction") risk score was obtained. Urine samples were collected and sent for quantitative determination of MAU. All patients underwent diagnostic coronary angiography. Data are give as mean (quantitative and percent) ± SD.

RESULTS

Fifty-three men (76%) and 17 (24%) women (mean age 56 ± 12 years) were investigated. Overall 37 (53%) individuals presented with arterial hypertension and 41 (59%) with a history of smoking. 58 patients (83%) had ischemic ECG changes (defined as ST segment depression more than 1 mm from baseline, and/or T wave inversion), 52 (74%) had echocardiographic findings indicative of ischemia (defined as segmental wall motion abnormalities). Twenty-one (30%) patients tested positive for MAU. There was a significant correlation of echocardiographic signs of ischemia and MAU, (n = 20 (38%), p < 0.01). There was a clear relationship between MAU and TIMI risk score. Additionally, MAU was more common in patients with multivessel coronary artery disease (CAD) (p < 0.001). There was no statistically significant correlation between MAU and mean age, sex, smoking, and blood pressure.

CONCLUSION

In this analysis of patients with UA/NSTEMI we found a strong correlation of microalbuminuria with echocardiographic changes and findings in coronary angiography.

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.

Microalbuminuria

Microalbuminuria, originally described more than 3 decades ago as a predictor of nephropathy in patients who had type 1 diabetes mellitus and associated with higher cardiovascular risk, is now linked with increased risk for cardiovascular events rather than progression to end-stage kidney disease. This article reviews the role of microalbuminuria in the context of atherosclerotic vascular disease. It presents the methods for microalbuminuria assessment in clinical practice, its relations with other cardiovascular risk factors, and the pathophysiologic associations between microalbuminuria and vascular damage. In addition, this article discusses the prognostic significance of microalbuminuria for cardiovascular disease as well as existing therapeutic interventions for reducing urine albumin excretion in patients who are at high cardiovascular risk.

Haemostasis, inflammation and renal function following exercise in patients with intermittent claudication on statin and aspirin therapy

Background

Previous studies have suggested that exercise in patients with intermittent claudication (IC) may induce a systemic thrombo-inflammatory response. The effect of secondary prevention therapy on this response is unknown. This study aimed to investigate the effects of treadmill exercise on markers of coagulation activation, inflammation and renal function in patients with IC, receiving aspirin and statin therapy compared to healthy controls.

Methods

Samples were taken before, immediately and 1 hour after exercising on a treadmill in 20 patients with IC and 20 healthy volunteers. Interleukin-6 (IL-6), thrombin-anti-thrombin complex (TAT) and fibrin D-dimer were measured by ELISA. High sensitivity CRP (HsCRP) and urinary albumin were measured via a nephelometric technique, urinary protein via a turbidometric assay and N-acetyl-β-D-glucosaminidase (NAG) via a colorimetric assay.

Results

Elevated baseline levels of Hs-CRP, IL-6, white cell counts, D-dimer and urinary NAG occurred in patients with IC compared to volunteers (p > 0.05). Following exercise there was no increase in Hs CRP or IL-6. D-dimer levels significantly increased following exercise in the patients and volunteers. TAT levels increased immediately after exercise in the patient group only and were significantly increased at 1 hour in both patients and volunteers. A transient rise in the protein creatinine ratio occurred in both groups (p < 0.007), and in albumin creatinine ratio in the patient group. There was no change in urinary NAG.

Conclusion

Elevated markers of inflammation occurred in patients with IC on statin and aspirin therapy but these did not increase following exercise. However, acute exercise resulted in a prothrombotic state evident in both groups, although this was more prolonged in patient with IC. The clinical significance of these findings in patients who are known to be at an increased risk of cardiac and other thrombotic event are unclear.

Effect of propionylcarnitine on changes in endothelial function and plasma levels of adhesion molecules induced by acute exercise in patients with intermittent claudication

In patients with intermittent claudication, treadmill exercise may cause acute deterioration of endothelial function and increase in plasma concentrations of adhesion molecules. The authors evaluated the efficacy of intravenously administered propionylcarnitine (PLC)in preventing these phenomena. Thirty-six claudicants with postexercise decrease in brachial artery flow-mediated dilation (FMD)were randomized to either placebo or PLC (600 mg as a single bolus followed by 1 mg/kg/min for 60 minutes).In the 18 patients randomized to placebo, FMD markedly decreased with exercise before (from 6.8 +/-0.4% to 4.0 +/-0.4%; p < 0.001) and after treatment (from 6.5 +/-0.4% to 4.4 +/-0.5%; p < 0.001). By contrast, in the PLC group, FMD significantly decreased with exercise before treatment (from 8.0 +/-0.7% to 4.4 +/-0.4%; p < 0.001), but not after active drug administration (from 7.1 +/-0.7% to 6.0 +/-0.6%; p = 0.067). The difference between treatments was not significant (p = 0.099; ANOVA). However, in the PLC group, the authors found that the greater the exercise-induced deterioration in endothelial function before treatment, the greater the capacity of PLC to prevent a postexercise decrease in FMD (r = -0.50, p = 0.034). Accordingly, they analyzed data in the 19 patients with a baseline exercise-induced decrease in FMD >or=45% (ie, the median FMD reduction in the entire group of 36 patients), and found that the exercise-induced FMD decrease was less after PLC than after placebo (p = 0.046, ANOVA). In the same subgroup, the exercise-induced increase in plasma concentrations of soluble vascular cell adhesion molecule-1 (sVCAM-1) was significantly higher before than after treatment in patients randomized to PLC (23.4 +/-5% vs 15.3 +/-7%, p = 0.007). In conclusion, in patients with intermittent claudication suffering from a greater endothelial derangement after treadmill, PLC administration provided a protective effect against deterioration of FMD and increase of sVCAM-1 induced by exercise.

Chronic Transcutaneous Electrical Stimulation of Calf Muscles Improves Functional Capacity without Inducing Systemic Inflammation in Claudicants

OBJECTIVES

To assess whether electrical stimulation of ischaemic calf muscles in claudicants causes a systemic inflammatory response and to evaluate effects of its chronic application on muscle function and walking ability.

DESIGN

Prospective randomised controlled trial of calf muscle stimulation.

MATERIALS AND METHODS

Stable claudicants were randomised to receive either active chronic low frequency (6 Hz) motor stimulation (n=15) or, as a control treatment, submotor transcutaneous electrical nerve (TENS) stimulation (n=15) of calf muscles in one leg, 3 x 20 min per day for four weeks. Leucocyte activation was quantified by changes in cell morphology, vascular permeability by urinary albumin:creatinine ratio (ACR), calf muscle function by isometric twitch contractions and walking ability by treadmill performance pre- and post-intervention.

RESULTS

Acute active muscle stimulation activated leucocytes less (28% increase) than a standard treadmill test (81% increase) and did not increase ACR. Chronic calf muscle stimulation significantly increased pain-free walking distance by 35 m (95% CI 17, 52, P<0.001) and maximum walking distance by 39 m (95% CI 7, 70, P<0.05) while control treatment had no effect. Active stimulation prevented fatigue of calf muscles during isometric electrically evoked contractions by abolishing the slowing of relaxation that was responsible for loss of force.

CONCLUSIONS

Chronic electrical muscle stimulation is an effective treatment for alleviating intermittent claudication which, by targeted activation of a small muscle mass, does not engender a significant systemic inflammatory response.

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.

Microalbuminuria: marker of vascular dysfunction, risk factor for cardiovascular disease

Based on the data from large single and multi-center clinical trials, including the Heart Outcomes Prevention Evaluation (HOPE) study, it is clear that the presence of microalbuminuria is a signal from the kidney that cardiovascular risk is increased and that vascular responses are altered. This is exemplified by studies that have demonstrated that the compensatory vasodilation seen following relief from prolonged ischemia or infusion of vasodilators such as nitroglycerin is blunted in people with microalbuminuria. Thus, the presence of between 30 and 299 mg/day of albumin in the urine is associated with abnormal vascular responsiveness, which may be the result of more advanced atherosclerosis and not necessarily related to the presence of hypertension or renal disease. Agents known to reduce the rise in microalbuminuria or actually reduce the level of microalbuminuria, such as ACE inhibitors, angiotensin receptor blockers, HMG-CoA reductase inhibitors, beta blockers, non-dihydropyridine calcium channel blockers and diuretics, have all been shown to reduce cardiovascular mortality and in some cases preserve renal function. This article will present an overview of the data that support the assertion that a reduction in the rise of microalbuminuria is a significant consideration in the selection of agents to treat a given risk factor (cholesterol or blood pressure) to a recommended target goal. Achieving such a goal with agents that also impact microalbuminuria will provide for a more complete cardiovascular risk reduction.

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.

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.

Differences in renal response between endovascular and open repair of abdominal aortic aneurysms

OBJECTIVES

to determine the difference in renal and systemic response between open and endovascular aneurysm repair.

MATERIALS AND METHODS

we studied prospectively 22 patients undergoing open repair (OR) and 15 patients undergoing endovascular repair (ER). Blood and urine samples were taken preoperatively (T0) and before clamping of the aorta or femoral artery (T1) and 5 min (T2), 1 h (T3), 6 h (T4), 24 h (Day 1) and 48 h (Day 2) after declamping. Albumin/creatinin ratio (AC ratio) in urine, serum albumin, serum creatinin, serum C-reactive protein and serum lactate were determined.

RESULTS

the urinary AC ratio in ER was significantly lower than in OR (p<0.001). In both groups the rise in urine albumin/creatinin ratio after declamping (T2, T3) was significant (p<0.001). C-reactive protein was raised significantly at day 1 and 2 in both groups (p<0.001) with no difference between the groups. Serum lactate values were significantly higher in OR. There was a significant increase in serum lactate 6 h after declamping in the ER group.

CONCLUSIONS

after endovascular repair renal damage is less compared to open repair. There is a significant systemic reaction to the endovascular repair causing mild, short-lasting damage to the kidney. This systemic response is most probably induced by a combination of ischaemia reperfusion injury and the surgical trauma of the procedure. Other possible explanations are discussed.

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.

Microalbuminuria as a predictive factor for cardiovascular events

We tested the hypothesis that microalbuminuria screening in a general practice setting would identify high-risk nondiabetic hypertensive patients, and we measured microalbuminuria response to drug treatment. General practitioners were enrolled who had collected medical histories and performed physical examinations and routine laboratory tests in more than 11,000 untreated hypertensive, nondiabetic patients. Microalbuminuria was measured with an albumin-sensitive immunoassay test strip. The patients' mean age was 57 years, 51% were men, and mean duration of hypertension was 69 months. Twenty-five percent of patients had coronary artery disease (CAD), 17% had left ventricular hypertrophy (LVH), 5% had had a stroke, and 6% had peripheral vascular disease (PVD). Microalbuminuria was present in 32% of men and 28% of women. In patients with microalbuminuria, 31% had CAD, 24% had LVH, 6% had had a stroke, and 7% had PVD. In patients without microalbuminuria, all of these rates were significantly lower: 22%, 14%, 4%, and 5%, respectively (p < 0.001). Furthermore, in patients with CAD, LVH, stroke, or PVD, microalbuminuria was significantly greater than in patients who did not have these complications (p < 0.001). A multiple stepwise regression analysis with microalbuminuria as the dependent variable showed microalbuminuria depended on the following factors, in order of importance: systolic blood pressure, retinopathy, CAD, diastolic blood pressure, and LVH (all p < 0.0001). A multiple stepwise regression analysis with each of the concomitant diseases as the dependent variable showed that microalbuminuria was an independent and significant variable for each of the conditions. The patients were assigned to monotherapy with either angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, calcium antagonists, or diuretics. All of the drugs reduced microalbuminuria, although the beta-blocker carvedilol was superior (p < 0.05). We concluded microalbuminuria is an important risk factor that can be influenced by treatment.

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.

von Willebrand factor and urinary albumin excretion are possible indicators of endothelial dysfunction in cardiopulmonary bypass

OBJECTIVE

Experimental evidence suggests that cardiopulmonary bypass (CPB) associated inflammatory response leads to endothelial injury and increased permeability, but this has been difficult to show clinically. We have investigated the use of von Willebrand factor (vWF), and urinary albumin excretion, as measured by the urinary albumin creatinine ratio (ACR), to demonstrate this.

METHODS

A total of 23 patients undergoing elective coronary artery bypass grafting were studied. Complement fragment C3a, leukotrienne B4 (LTB4), interleukin 6 (IL6), neutrophil elastase, vWF and ACR were measured on anaesthetic induction (baseline), 20 min after starting CPB, 5 min after cross-clamp removal, 5 min, 2, 6 and 24 h after termination of CPB. Anaesthetic, CPB and myocardial protection techniques were standardised. ANOVA was performed by using the distribution free Friedman test for each measured parameter. When significance differences were found (P < 0.05), post hoc analysis with Wilcoxon signed rank test was used for comparison of each time point with the base line level and differences were only accepted as significant following the Bonferroni correction (P < 0.008). Summary measures of peak versus peak and area under the cure were also analysed for ACR with vWF.

RESULTS

Peak vs. baseline levels for C3a were 4.9 vs. 2.1 microg/ml (P < 0.0001), LTB4 was 800 vs. 20 pg/ml (P < 0.0001), neutrophil elastase was 250 vs. 115 ng/ml (P < 0.001), IL6 was 620 vs. 1.4 pg/ml (P < 0.0001), vWF was 2.2 vs. 1.3 IU/ml (P < 0.0001) and ACR was 17.6 vs. 2.0 mg/mmol (P < 0.0001). C3a, LTB4 and ACR peaked during the operation. Neutrophil elastase peaked at 2 h following CPB. IL6 and vWF peaked at 6 h following CPB. The correlation coefficient between vWF and ACR following peak versus peak analysis was 0.48 (P = 0.035), and area under the curve analysis was 0.6 (P < 0.01).

CONCLUSION

These results demonstrate that endothelial permeability and injury, as measured by urinary albumin excretion and vWF, respectively, are related and the use of these easily detectable and sensitive biochemical markers warrants further investigation.

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.

Urinary microalbumin as a marker for intermittent claudication

OBJECTIVE

The urinary microalbumin concentration was analysed in patients with intermittent claudication in order to investigate its usefulness as a marker for intermittent claudication.

MATERIALS AND METHODS

Urinary samples were collected prior to and following exercise in 15 patients with claudication. The patients walked on a treadmill as far as possible until they were stopped by pain. Urinary microalbumin concentration was measured by a latex agglutination system, and the result was considered abnormal when the concentration exceeded 10 mg/g creatinine. The ankle brachial pressure index (ABI) at rest and the time taken for the ankle pressure to return to the resting level following exercise (ABI recovery time) also were measured.

RESULTS

In seven (47%) of the patients, the urinary microalbumin concentration was elevated to more than 10 mg/g creatinine following exercise, while in eight (53%) it remained normal. The ABI recovery time was significantly longer in the patients in whom the microalbumin concentration was elevated, compared to that in patients without an elevated concentration. The urinary microalbumin concentration following exercise was reduced significantly when the walking distance was decreased 50% or 15%. Following vascular bypass surgery, the elevation in urinary microalbumin concentration was reduced.

CONCLUSIONS

The use of urinary microalbumin as a diagnostic marker for intermittent claudication is limited. However, in cases where the concentration is elevated, it can be used to follow the course of the disease.

Antioxidant consumption during exercise in intermittent claudication

Twenty male claudicant patients and nine age-matched controls were exercised on a treadmill. Blood and urine samples were taken before and after exercise. Total antioxidant concentration was measured using an enhanced chemiluminescent assay and microalbuminuria determined by radioimmunoassay. Claudicants had increased microalbuminuria after exercise. Mean (s.e.m.) antioxidant concentrations were similar for patients and controls at rest: 479(28) and 438(23) mumol/l respectively. Claudicants showed a significant decrease in antioxidant concentration 1 min after exercise to 428(27) mumol/l; this returned to 470(30) mumol/l by 10 min. A correlation was found between the decrease in antioxidant concentration and the increase in microalbuminuria (rs = -0.496, P < 0.05). This study supports the concept of ischaemia-reperfusion injury in claudicant patients and has implications for treatment.

Treatment of intermittent claudication: the impact on quality of life

OBJECTIVES

To measure changes in claudicant's quality of life after surgery, angioplasty or unsupervised exercise. To explore the relationship between clinical indicators of limb perfusion and patient's perception of health change.

DESIGN

Prospective study.

SETTING

University Hospital vascular outpatients.

MATERIALS AND METHODS

202 claudicants referred for Duplex of lower limb arterial disease over a 12 month period. The short form 36 questionnaire was used to determine quality of life. Ankle pressures and walking distances were determined.

MAIN RESULTS

The SF-36 was completed by 186 patients (92%) before and after treatment (34 operative patients, 74 angioplasty and 78 treated by exercise alone). Baseline quality of life was worse in surgical patients. Unsupervised exercise produced minimal changes in quality of life. Angioplasty and operation produced similar, significant improvements in physical functioning and pain. Changes in physical function or pain scores were unrelated to changes in ankle pressure.

CONCLUSIONS

Unsupervised exercise programs are unlikely to significantly improve patient's quality of life. The benefits of surgery and angioplasty support a relaxation in the indications for investigation and treatment of claudicants. Patients with impaired perceived health should not be denied treatment on the basis of preintervention ankle pressure or walking distance alone.

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

OBJECTIVES

It has been postulated that ischaemia-reperfusion occurs in intermittent claudication resulting in neutrophil activation and release of soluble mediators, increasing systemic vascular permeability and enhancing atherogenesis.

METHODS

We measured neutrophil deformability, plasma thromboxane levels, and urinary microalbumin excretion in 30 male claudicants, and 10 age- and sex-matched controls, before and after exercise to maximum walking distance. Blood was taken from an antecubital vein.

RESULTS

There was an increase in urinary microalbumin excretion after exercise in claudicants. Statistically significant increases in the median and 90th percentile transit times (markers of neutrophil deformability) for isolated neutrophils from blood drawn 5 min after exercise in the claudicants were observed with no change in control subjects. Plasma thromboxane concentrations in claudicants increased within 10 min post-exercise. Plasma concentrations in controls were significantly lower throughout the study period. In the claudicant group, a positive correlation between the percentage change in the median transit time for neutrophils, and the percentage change in plasma thromboxane at 60 min post-exercise was found.

CONCLUSIONS

The results lend further support to the concept of ischaemia-reperfusion events in patients with intermittent claudication, leading to a systemic increase in vascular permeability as a result of endothelial injury or dysfunction (a crucial step in atherogenesis), associated with thromboxane production and neutrophil activation. We suggest that the above changes may contribute to the increased mortality seen in such patients.

Microproteinuria predicts the severity of systemic effects of reperfusion injury following infrarenal aortic aneurysm surgery

Noncardiogenic pulmonary dysfunction can be demonstrated in all patients following elective aortic aneurysm repair and is a cause of postoperative morbidity. Aortic clamping and reperfusion initiate a systemic inflammatory response producing endothelial damage and increases in vascular permeability. In the lung this is manifest as pulmonary edema and in the kidney as detectable increases in urinary protein excretion (microproteinuria). Immunoassay of low-level protein excretion appears to provide an index of the systemic effects of local reperfusion injury and may allow early prediction of complications such as pulmonary edema. Hourly urinary albumin and IgG excretion was measured in 40 patients undergoing infrarenal aortic aneurysm repair and expressed as ratios to urinary creatinine (albumin/creatinine ratio [ACR] and IgG/creatinine ratio [IgGCR]). These were compared to clinical outcome. Pulmonary dysfunction was assessed according to PaO2:FiO2 ratios and chest radiography. Within 180 minutes of beginning surgery all patients had significant increases in ACR and IgGCR. Ten patients who manifested respiratory dysfunction had significantly higher ACRs at 4 hours (median 84.8, 95% confidence intervals, range 47.7 to 136) than patients who made uneventful recoveries (median 16.6, 95% confidence intervals, range 7.9 to 31.7). IgGCR increases paralleled that of ACRs. Differences persisted for 24 hours. Urinary protein excretion rises rapidly during aortic surgery. The degree of increase appears to predict development of pulmonary dysfunction. This simple test may provide a rational basis for evaluation of therapeutic modalities to limit reperfusion injury in these patients.

Intermittent claudication incites systemic neutrophil activation and increased vascular permeability

Reperfusion following severe ischaemia incites a systemic response involving neutrophil activation and vascular injury. Recent work suggests that intermittent claudication may also be capable of inducing similar changes, reversible by revascularization. This observation may have implications for the treatment of claudication and explain the high associated cardiovascular mortality. This hypothesis was investigated using an in vivo model. Rats underwent repeated hindlimb stimulation after common iliac artery ligation. Intravital fluorescence microscopy was used to observe postcapillary venules of the tibialis anterior muscle in the hindlimb. This revealed a bilateral increase in leucocyte-endothelial adhesion and vascular permeability to albumin after unilateral subtotal ischaemia and muscle stimulation, associated with increased urinary albumin excretion. These results provide further evidence supporting the association of intermittent claudication with potentially deleterious systemic manifestations.