Claudication Medical Therapy for Peripheral Arterial Disease
Exercise Training
The use of a formal exercise program to treat claudication has been studied over the past 30 years. Exercise therapy for claudication had demonstrated efficacy in terms of improving exercise performance, quality of life, and functional capacity. Numerous types of exercise programs have been devised, but the most successful employ a supervised exercise setting. Patients should also undergo an exercise test to maximal claudication pain. A typical supervised exercise program is 60 min in duration and is monitored by a skilled nurse or technician.
Patients should be encouraged to walk primarily on a treadmill because this most closely reproduces walking in the community setting. The initial workload of the treadmill is set to a speed and grade that brings on claudication pain within 3 to 5 min.
Patients walk at this work rate until they achieve claudication of moderate severity. They then rest until the claudication abates and then resume exercise. This repeated on-and-off form of exercise is continued throughout the supervised rehabilitation setting. On a weekly basis, patients should be reassessed as they are able to walk farther and farther at their chosen workload; this then will necessitate an increase in speed or grade or both to allow patients to successfully work at harder and harder workloads. This scenario then induces a training benefit. The duration of an exercise program is 3 to 6 months. The typical benefits include a 100% to 200% improvement in peak exercise performance on the treadmill and significant improvements in functional status.
Drug Therapy for Claudication
Vasodilators were an early class of agents used to treat claudication but have not been shown to have clinical efficacy. In 1984, pentoxifylline was approved for the treatment of claudication. In early controlled trials, the drug produced a 12% improvement in the maximal treadmill walking distance. However, in a recent study, pentoxifylline was no more effective than placebo on improving treadmill walking distance or functional status assessed by questionnaires. A meta-analysis concluded that the drug produced modest increases in treadmill walking distance over placebo, but the overall clinical benefits were questionable.
Cilostazol is currently the most effective drug for claudication. Approved in 1999, the primary action of cilostazol is to inhibit phosphodiesterase type 3, which results in vasodilation and inhibition of platelet aggregation, arterial thromboses, and vascular smooth muscle proliferation. In four trials of 1534 patients, cilostazol 100 mg twice daily improved both pain-free and maximal walking distance as compared with placebo. In one trial, cilostazol 100 mg twice daily was superior to both placebo and pentoxifylline. In three of the trials, cilostazol also improved several aspects of physical functioning and quality of life as assessed by questionnaires. The most common side effects of cilostazol are headache, transient diarrhea, palpitations, and dizziness. Cilostazol should not be given to patients with claudication who also have heart failure.
Additional drugs are in clinical trials for treating claudication. Propionyl-l-carnitine is a metabolic agent that has been shown to improve treadmill performance and quality of life in patients with claudication. Prostaglandins have been extensively studied in patients with PAD, but with mixed results. In a recent study, beraprost, an oral prostaglandin, had positive effects on treadmill walking distance and quality of life. However, these drugs are still under study and their utility needs further evaluation. Very few studies have addressed the issue of combined drug plus exercise therapy for claudication. However, the available data suggest at least an additive effect of exercise training plus a drug for claudication.