Atherosclerotic cardiovascular disease is the most significant health problem in the United States, as heart and cerebrovascular diseases are leading causes of mortality and peripheral vascular disease is a leading cause of morbidity in elderly people. Peripheral arterial disease (PAD) is the most typical form of peripheral vascular disease. PAD is characterized by a partial or complete failure of the arterial system to deliver oxygenated blood to peripheral tissue. Atherosclerosis is, by far, the most common etiology of PAD. However, several other processes can lead to the clinical syndrome (Table 80-1). Although lesions (and symptoms) of PAD can occur in both the upper and the lower extremities, these are much more common in the lower extremity, which is the focus of this chapter.
Table 80-1 Causes of Peripheral Arterial Disease ||Download (.pdf)
Table 80-1 Causes of Peripheral Arterial Disease
The ankle–brachial blood pressure index (ABI), defined as the systolic blood pressure measured at the ankle divided by the systolic blood pressure measured in the arm during supine rest, is the most widely used quantitative measure to identify subjects with PAD and to determine PAD severity. The ABI varies widely in the general population and is generally normally distributed with a long tail of low values (Figure 80-1). The prevalence of PAD is highly dependent on the exact ABI cutpoint used to detect inadequate peripheral circulation. The definition of an abnormal ABI has ranged between <0.80 and <0.97, with a value of ≤0.90 generally considered to be the best reference standard.
Ankle–brachial blood pressure index (ABI) in men and women in the Edinburgh Artery study. The bars and left-hand scale represent the percentage of subjects having a given ABI. The solid line and right-hand scale represent the cumulative percentage of subjects having an ABI at or below the ABIs listed on the abscissa. (Adapted from Fowkes FG. Epidemiological research on peripheral vascular disease. J Clin Epidemiol. 2001;54:863.)
The prevalence of PAD is 16% in the general population older than 55 years of age when an ABI value of ≤0.90 and symptoms of intermittent claudication and rest pain are used as criteria of PAD. In the Edinburgh Artery Study, approximately 20% of the men and women aged 55 to 74 years were noted to have an ABI ≤0.90 and, thus, were diagnosed as having PAD. The prevalence of PAD increases with age and at all ages is higher in men than in women. At ages 65 to 69 years, the prevalence of PAD in men from the Cardiovascular Health Study was approximately 7%, and approximately 5% in women. In subjects aged 85 years and older, the prevalence was 23% in men and 21% in women.