Current therapy for intermittent claudication

Benefits of a Supervised Exercise Program After Lower Limb Bypass Surgery

This study evaluated the efficacy of an exercise program after arterial bypass surgery. Patients undergoing bypass surgery were randomized to a control group (group I), with standard preoperative and postoperative care, or the intervention group (group II) with a supervised exercise program of twice-weekly treadmill assessments from 4 to 10 weeks postoperatively. Ankle-brachial pressure indices and hemodynamic measurements were recorded before and after exercise. The mean increase of maximum walking distance was 3.8% in group I and 175.4% in group II ( P = .001). There was a significant difference between group I and II in the mean ankle-brachial pressure indices increase at the second assessment (0.08 versus 0.23; P = .02). A supervised exercise program leads to better improvement after lower limb bypass surgery for ischemia, but the feasibility of a formal exercise program would be undermined by the reluctance of patients to participate, both in the short-term and long-term.

Structural adaptation to ischemia in skeletal muscle: effects of blockers of the renin-angiotensin system

OBJECTIVE

To investigate the effects of long-term treatment with blockers of the renin-angiotensin system on capillarization and growth of fibers in ischemic hind-limb muscles and in muscles under normal growth conditions.

METHODS

Ischemia was induced by partial ligation of the left common iliac artery.

RESULTS

Ischemia resulted in a significant increase in capillary and fiber density in the soleus muscle, a significant decrease in mean fiber size and a decrease in muscle cross-sectional area after 4 weeks compared with the contralateral nonischemic muscle. Ischemia also significantly decreased the muscle: body weight ratio of the left soleus muscle. We observed no significant effect on total number of capillaries and capillary: fiber ratio, suggesting that ischemia did not result in an increase in capillarization in this muscle. Treatments with subhypotensive and with hypotensive doses of the angiotensin converting enzyme (ACE) inhibitor benazeprilat, the angiotensin (Ang) II AT1 antagonist valsartan, or the Ang II AT2 antagonist PD 123 319 for 4 weeks did not influence any of the above-described changes in the normal and ischemic muscles and treatment effects were also independent of the degree of reduction of blood pressure.

CONCLUSION

Treatments with an ACE inhibitor and with Ang II receptor antagonists in dose ranges that moderately lower blood pressure do not influence vessel density and any of the other structural adaptations after hind-limb ischemia. Administrations of ACE inhibitors and Ang II AT1 antagonists may therefore be adequate and beneficial therapies under ischemic conditions, such as in the treatment of hypertension complicated by intermittent claudication, for which treatment must not increase ischemia.

Controlled clinical trial on the efficacy and safety of oral sulodexide in patients with peripheral occlusive arterial disease

One hundred and seven adult outpatients with Leriche stage II peripheral occlusive arterial disease took part in this open, controlled trial. Patients were randomly treated over a six-month period either with sulodexide capsules containing 250 lipoproteinlipase releasing units (LRU, two capsules twice daily for 176 days on average: 56 patients), or with pentoxifylline 400 mg tablets (one tablet three times a day for 180 days on average: 51 patients). The incidences of diabetes, hyperlipoproteinaemias, smoking habit and other risk factors were the same in the two groups. The drugs' efficacies were evaluated by monitoring, at the start of treatment and every month during it, the Winsor Index and the walking distance, both prior to (initial claudication distance-IDC) and after (absolute claudication distance-ACD) the symptom's onset. Compliance with treatment and occurrence of adverse events were constantly monitored; systemic tolerability was evaluated through the use of routine haematological and haematochemical tests. Both treatments brought about a progressive increase in the claudication-free walking distance, statistically significant versus baseline from the second month (ACD, sulodexide group) and third month (ACD and ICD, pentoxifilline and sulodexide groups). At the end of treatment, the absolute increase of ACD was significantly greater in sulodexide-treated patients (p < 0.01) with respect to the pentoxifylline-treated group. In both groups the Doppler test evidenced a good improvement in local arterial haemodynamics. In the sulodexide group, 3.6% of patients developed nausea, dyspepsia and other minor gastrointestinal phenomena. In the pentoxifylline group 17.6% of patients complained of gastroenteric disorders (nausea, vomiting, dyspepsia), or of headache and dizziness. In one patient of this latter group insomnia was also present. Systemic tolerance of both drugs was consistently good.

Antihypertensive therapy and adaptive mechanisms in peripheral ischemia

In the present experiments the effect of long-term peripheral ischemia on the capillary of two hind limb skeletal muscles was investigated in spontaneously hypertensive rats. Furthermore, the effect of antihypertensive therapy on changes in capillarity and on the previously observed hyperreactivity of the ischemic vascular bed to vasoconstrictors was investigated in perfused hind limbs of rats after long-term treatment with the angiotensin I converting enzyme inhibitors captopril (0.5 mg/kg.h) or zabiciprilate (0.025 mg/kg.h), the angiotensin II type 1 receptor antagonist losartan (0.625 mg/kg.h), or the calcium antagonist felodipine (0.042 or 0.42 mg/kg.h). Skeletal muscle ischemia in the left hind limb was induced by partial ligation of the left common iliac artery. Long-term (4 weeks) ischemia increased significantly the capillary-to-fiber ratio in the soleus muscle, composed predominantly of type I fibers in spontaneously hypertensive rats, of the ischemic hind limb, whereas capillarity in the contralateral muscle was not affected. Furthermore, capillarity in the gastrocnemius muscle (type II muscle fiber part) of both the ischemic and contralateral hind limb did not change. Long-term treatment with the angiotensin I converting enzyme inhibitors during ischemia abolished the increase in the capillary-to-fiber ratio in the soleus muscle, whereas a comparable antihypertensive dose of felodipine had no effect. Greater blood pressure reductions by both losartan and felodipine prevented increases in capillarization in skeletal muscle ischemia. With respect to vascular hyperreactivity during ischemia, only treatment with losartan normalized reactivity of the ischemic vascular bed to vasoconstrictors.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological approaches to the treatment of intermittent claudication

Intermittent claudication is a common condition of the elderly, occurring in 3 to 20% of individuals over the age of 65 years. Although local disease is usually benign, life expectancy in patients with intermittent claudication is reduced by approximately 10 years due to associated cardiovascular mortality. Several classes of drugs have been used in intermittent claudication, but clinical studies evaluating their efficacy leave much to be desired. Pentoxifylline (oxpentifylline), a rheological agent, and naftidrofuryl, an enhancer of aerobic metabolism, are the 2 most widely investigated and utilised drugs. The combined results of 10 placebo-controlled studies with pentoxifylline and 4 with naftidrofuryl estimate increases in claudication distances of 51 and 42%, respectively. However, due to publication bias, these figures are probably overestimates of the true benefit from treatment with these drugs. It is likely that any benefit from pentoxifylline or naftidrofuryl is small and of little clinical importance. The suggestion that naftidrofuryl has greater efficacy in older patients remains unproven. Other classes of drugs including vasodilators, antiplatelet drugs, anticoagulants and prostaglandins have not been shown to be effective. Only 2 approaches to the management of intermittent claudication have been shown convincingly to be of benefit: stopping smoking and exercising regularly.

Fish oil supplementation in patients with stable claudication

Increased blood viscosity occurs in patients with claudication. This increase in viscosity, which is mainly due to elevated fibrinogen levels and a decreased red cell deformability, adversely influences blood flow. In addition to a positive effect on blood pressure, blood lipids, and platelet responsiveness, fish oil may improve blood flow due to a favorable influence on hemorrheology. In a prospective, randomized, double-blind study, we evaluated the effect of six capsules of fish oil (1.8 g eicosapentaenoic acid and 1.2 g docosahexaenoic acid) versus six capsules of corn oil (3 g linoleic acid), administered for 4 months, on walking distances, pressure indices during rest and after exercise, blood pressure, red cell deformability, fibrinogen, and lipid levels in 32 patients with stable claudication. No significant changes in walking distances and pressure indices during rest and after exercise occurred, despite a significant increase in red cell deformability in the fish oil group. Fibrinogen levels did not change in either group. In the fish oil group, a favorable change in blood lipids was noted; high-density cholesterol increased and triglycerides decreased. Mean arterial blood pressure declined to a similar extent in both groups. Thus, short-term supplementation with fish oil does not lead to clinically significant improvement of symptoms in patients with stable claudication. This suggests that red cell deformability is of minor importance in the arterial blood flow in the legs of these patients.

Placebo-controlled, double-blind study of the effect of verapamil in intermittent claudication

The clinical effect of verapamil was tested in 24 patients with intermittent claudication in a randomized, placebo-controlled, double-blind, crossover study. Slow-release verapamil or placebo was given for two periods of three weeks. The walking distance, systemic blood pressure, and ankle-brachial blood pressure index were measured. Furthermore, a possible change in peripheral vascular tone was provoked by hyperventilation. The walking distance rose after both verapamil (40%) and placebo (31%) (p less than 0.01 for both) but tended to increase only after verapamil (7%) as compared with placebo. Blood pressure fell equally after both verapamil and placebo (p less than 0.05 for both). Verapamil did not influence the ankle-branchial blood pressure index. No signs of vasoactivity in the lower extremities were seen after hyperventilation. Although the greatest individual improvements in walking distance were seen after verapamil administration, it was not possible to predict positive responders among the patients.

Drug effects on function in the ferret ischemic hindlimb

In this article a new model of peripheral occlusive arterial disease is described. The lower hindlimb of an anesthetized ferret was fixed to a holder, the distal end of the Achilles tendon attached to an isometric force transducer, and a passive preload of 100 g was applied to the muscle preparation. The hindlimb was stimulated to contract isometrically via supramaximal electrical stimulation of the sciatic nerve. During the initial period, when femoral blood pressure equaled aortic blood pressure, net contractile force peaked within 1 or 2 min (372 +/- 24g, n = 20) and gradually declined to about 85% of peak over 20 min. Following 60 min of ischemia (induced by partial occlusion of the abdominal aorta), when blood pressure in the contralateral femoral artery was about 45 mm Hg, the 15-min area under the force-time curve (AUC) was 33.2 +/- 2.5% (n = 4) of the initial value. To validate the utility of this model in the search for treatment of peripheral vascular diseases, two drugs were tested. Pentoxifylline, which is clinically effective, attenuated the loss of function observed during ischemia in a dose-related manner, but nifedipine, which is without clinical benefit, had no effect at a dose that was extremely hypotensive. Because femoral perfusion pressure was controlled, systemic hemodynamic effects of test compounds are minimized as potential mechanisms of action, simplifying the evaluation of novel pharmacotherapy for treatment of ischemic diseases.

Current therapy of peripheral obstructive arterial disease. The non-surgical approach

In recent years double-blind trials have proved the effectiveness of nonsurgical therapy in the treatment of peripheral obstructive arterial disease (POAD). Among the non-pharmacologic measures taken, walking distance was increased by 40% in subjects who stopped smoking and by more than 100% in those who undertook physical exercise. Drug treatment reduces the atherosclerotic process and brings about an improvement in the symptoms of the disease. In subjects given hypolipidemic treatment the progression of the disease was reduced by two thirds. Two separate studies suggest that antiplatelet drugs, taken over a period of two to four years, significantly slow the progression of atherosclerosis in lower extremity arteries. In the treatment of claudication, two vasodilating drugs, naftidrofuryl and buflomedil, have shown a significant improvement in painfree walking distance and/or total walking distance, compared with treatment with placebo. Another effective approach is in the treatment of blood rheology through drugs such as pentoxifylline or by hemodilution. Double-blind trials with pentoxifylline demonstrated an average increase of 66% in maximum walking distance as compared with 22% with placebo. The effectiveness of hemodilution was demonstrated by two controlled trials, during which the reduction of the hematocrit to values of 40-42 for periods of four to six weeks increased both walking distance and resting blood flow. When introduced intraarterially in low doses in the vicinity of the occluding thrombus, thrombolytic agents have been found to be helpful in the treatment of acute and chronic POAD. This therapy should, however, be regarded as a substitute for surgical treatment only in high-risk patients. Further, after having produced the lysis of thrombi, the treatment permits the underlying parietal lesions to be accurately identified; at this point the appropriate therapy can be decided upon, either an operative procedure or a balloon dilation. In conclusion the many controlled clinical trials carried out over the past few years have clearly demonstrated that conservative treatment can alleviate clinical signs and symptoms in patients with claudication and pain at rest.

Effects of physical training on peripheral vascular disease: a controlled study

The effects of physical exercise on 8 stage II peripheral vascular disease (PVD) patients were observed after a six-month training program. Doppler velocimetry (including the treadmill test), strain gauge plethysmography, and transcutaneous oxygen pressure were used to quantify the results, which were compared with those obtained in a control group of another 8 stage II PVD patients, under placebo therapy for six months. The results show physical exercise increased the walking capacity, both the pain-free walking time and the maximum walking time. No significant difference was observed in the other parameters studied, in either the exercise patients or the control group.

Drug treatment of intermittent claudication: a critical analysis of the methods and findings of published clinical trials, 1965-1985

1. All trials of drug therapy for intermittent claudication published in English during the period 1965-1985 were reviewed. A total of 75 trials had studied 33 different pharmacological agents. Treadmill exercise, the most reproducible method of evaluating symptoms in this condition, was used in 49% of trials. 2. Oxpentifylline was the drug that had been most frequently studied. In seven placebo-controlled trials the average response to oxpentifylline, compared with placebo and weighted for sample-size, was 65% improvement in claudication distance. There was, however, a significant negative relation between sample-size and response (rs = -0.79, P less than 0.05), suggesting that this estimate was likely to have been biased by non-publication of negative results. 3. One third of all trials were uncontrolled; 84% of these reported benefit from drug treatment, compared with 32% of placebo-controlled trials (P less than 0.001). Sample-sizes varied from seven to 227 patients; 31% of trials reported data from less than 20 patients and these were likely to have had insufficient statistical power. 4. Overall, 57 of the 75 trials (76%) had at least one of the following deficiencies: an uncontrolled design; not double-blind; failure to use treadmill exercise; less than 20 patients included in the analysis. Thus, a priori three-quarters of all trials were unlikely to have made a satisfactory assessment of drug efficacy. 5. The information available does not establish convincingly that any drug consistently improves exercise performance in intermittent claudication. In view of the deficiencies in previous trials, we propose guidelines for future studies with regard to trial design, sample-size and methods of exercise testing.

Multicenter double-blind study of ticlopidine in the treatment of intermittent claudication and the prevention of its complications

In this multicenter trial 169 patients with chronic intermittent claudication due to obstructive peripheral vascular disease were randomized in a double-blind fashion into two parallel groups receiving either 250 mg ticlopidine or placebo, twice daily. At entry, the two groups (83 ticlopidine, 86 placebo) were well matched for the major clinical features apart from an excess of women in the ticlopidine group. At six months, 167 patients were alive, 2 having died of malignant disease (1 from each group). At this stage, 39 patients from the ticlopidine group and 29 from the placebo group (p = 0.04) had increased their walking distance by more than 50% of baseline values. For the groups as a whole pain-free and total walking distance were greater in the ticlopidine group than in the placebo group (194 vs 124 meters, p = 0.03 and 236 vs 170 meters, p = 0.04, respectively). Two patients from the ticlopidine group vs 9 patients from the placebo group (p = 0.03) developed significant cardiovascular events during the study. These results indicate that ticlopidine has a beneficial effect both in the treatment of the symptoms and the prevention of vascular complications in patients with intermittent claudication.

Thromboembolism and antithrombotic therapy in peripheral arterial disease

Atherosclerosis complicated by thromboembolism is the main cause of obstructive arterial disease in the legs. Two studies from West Germany suggest that antiplatelet drugs may slow the progress of atherosclerosis in leg arteries and prevent occlusive thrombosis under some circumstances. The same agents may also reduce the risk of rethrombosis after successful vascular repair in the femoropopliteal region; in one trial, aspirin decreased the incidence of reocclusion after thromboendarterectomy and, in another, the combination of aspirin and dipyridamole was effective after bypass with synthetic material. Antithrombotic drugs are used in most centers after percutaneous transluminal angioplasty, but there is no definite evidence for their need. Thus, it appears that in contrast to cardiac and cerebrovascular disease, few efforts have been made to determine the true value of antithrombotic therapy in peripheral arterial disease. The management of acute thromboembolism in the legs requires a multidisciplinary approach. Depending on the type (embolic or thrombotic), length and localization of the arterial occlusion, surgical (embolectomy, thromboendarterectomy, peripheral bypass surgery) or nonsurgical (systemic fibrinolysis or local thrombolytic therapy with or without balloon angioplasty) treatment is preferred. The importance of nonsurgical therapeutic approaches may become even greater in elderly patients with a poor operative risk. This review discusses the available therapeutic modalities in acute and chronic peripheral thromboembolic arterial disease.

Placebo-controlled, double-blind, two-centre trial of ketanserin in intermittent claudication

The effects of ketanserin, a serotonin antagonist, were studied in 37 patients with intermittent claudication in a double-blind placebo-controlled, trial done in London and Leuven. 40 mg ketanserin taken orally three times a day for 4 months was associated with a clear-cut inhibition of serotonin-induced platelet aggregation but no changes were observed in pain-free and maximum walking distance on a treadmill, in ankle/arm Doppler systolic blood pressure ratio, or in reactive hyperaemia after 3 min of ischaemia. In contrast, the placebo group had increases in both pain-free and maximum walking distance (p less than 0.05).

Effects of flunarizine and pentoxifylline on walking distance and blood rheology in claudication

Thirty-one patients, mean age 60 years (range 45-80 years), with a typical history and objective symptoms of intermittent claudication with a reported maximal walking distance less than 500 m, were included in a cross-over study. After a one month's run-in period on placebo, the patients were randomized into two groups: one group started with flunarizine (5 mg t.i.d.) and the other with pentoxifylline (400 mg t.i.d.). The treatment lasted 3 months, whereafter the medications were changed. The trial followed a double-blind design. The median of the maximal walking distance was 255 m after the placebo period, increasing significantly (p less than 0.01) during both medication periods: by 43% and 18% during flunarizine and pentoxifylline, respectively. No changes were recorded in the ankle systolic blood pressure ratio ( ASBP -ratio) after placebo or either medication period. Red cell rigidity (Pmax), which was initially elevated, decreased significantly (p less than 0.05) during both medication periods, but there were no significant differences between the two drugs. No changes were found in whole blood or plasma viscosity. We conclude that the decrease in red cell rigidity may have contributed to the increased walking distance.