What You Should Know About Screening For PAD
- Volume 21 - Issue 5 - May 2008
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We are an aging population. One can ascertain that with aging comes an increased incidence of comorbid conditions. With the vast majority of podiatric surgical cases being elective, documentation supporting the vascular system prior to surgery will protect the surgeon from postoperative complications associated with circulatory issues, or may help surgeons recognize an asymptomatic issue for appropriate intervention prior to surgery. Recognition of asymptomatic circulatory issues is of particular importance in the younger diabetic population prior to surgery.
Systemic atherosclerosis is one of the many complications of poorly controlled diabetes that results in peripheral arterial disease (PAD). The consequences of systemic atherosclerosis can end with lower extremity amputations, ischemic heart disease, cerebrovascular disease and/or death.1 Podiatric physicians can aid in the early diagnosis of PAD by familiarizing themselves with the risks and symptoms associated with the disease.
Approximately 12 million people in the United States have PAD and patients with diabetes reportedly comprise between 20 and 30 percent of the PAD population.2 However, the prevalence could be higher because many patients with diabetes demonstrate factors that would affect clinical findings. Many patients with diabetes are asymptomatic and this could very well be the result of peripheral neuropathy masking the symptoms of intermittent claudication.3 In fact, 53.8 percent of the general population with PAD is asymptomatic so looking at the pathophysiology and risk factors is essential to aid in recognizing patients who need further evaluation.4
Atherosclerosis, the primary cause of PAD, is a systemic condition caused by a chronic inflammatory condition. One may see an elevated level of C-reactive protein (CRP) among patients with atherosclerosis as well as patients with impaired glucose tolerance. This finding is associated with the development of PAD.5 High levels of CRP inhibit the vasodilatory effects of nitric oxide (NO), which subsequently produce an uncharacteristic vascular tone. Diabetes further impairs the effects of NO due to hyperglycemia, excess free fatty acids and insulin resistance.6
Not only is the vasodilation of arteries affected by diabetes but the vasoconstriction of arteries is augmented by the induction of arthrogenic pathways. This occurs via activation of protein kinase C and nuclear factor kappa-B. Protein kinase C has an adrenergic effect on vascular smooth muscle, producing vasoconstriction. Nuclear factor kappa-B resides within a cell and becomes a first-responder through gene expression to aid in an immune response to initiate inflammation.7
Overall, atherosclerosis has the same pathophysiology in non-diabetics and patients with diabetes. However, the presence of diabetes further enhances the process of atherosclerosis and more commonly involves the vessels below the trifurcation in the lower extremity.8 Accordingly, this may correlate to the increased lower limb amputations one sees in the diabetic community.