Nonatherosclerotic Arterial Disorders of the Lower Extremities

Abstract

Atherosclerotic peripheral artery disease (PAD) is common, estimated to affect 4.3% to 29% of the adult population.1,2 PAD is an important syndrome to identify promptly because it is associated with an increased risk of premature myocardial infarction, stroke, and all-cause mortality.3 The public has limited appreciation for the disorder and its associated risks, making awareness of this disorder a high priority.4 Conversely, nonatherosclerotic artery diseases of the lower extremities (nonatherosclerotic PAD [NAPADs]) represent a heterogeneous group of uncommon conditions (Figure 1). Given the frequency of symptoms of leg discomfort, these disorders must also be considered in the differential diagnosis of patients who may not have the classic profile of atherosclerosis. Although each condition has distinctive pathophysiology, clinical manifestations, treatment, and prognosis, NAPAD also has unifying characteristics. Furthermore, left undiagnosed or mismanaged, these conditions may result in seriously adverse outcomes that may otherwise have been avoided or minimized. Figure 1. Examples of various types of lower-extremity peripheral artery disease. A , Halo sign caused by artery wall edema, typical of vasculitis. B , Computed tomographic angiography reconstruction of lower extremities revealing diffuse arterial calcification, typical of atherosclerosis. C , Angiography revealing transient occlusion of the popliteal artery on active plantar flexion (right), consistent with popliteal artery entrapment. D , Typical beaded appearance of the medial fibroplasia type of fibromuscular dysplasia (FMD) in the right external iliac artery. Note the associated aneurysms of the common iliac arteries, potentially representing aneurysms associated with FMD or combined atherosclerosis and FMD. Patients with symptoms of exertional limb discomfort or physical examination findings suggestive of lower-extremity arterial ischemia may have PAD; however, it is important to differentiate between PAD and NAPAD. Given the uncommon nature of NAPAD, the differential diagnosis is unfamiliar to most clinicians. PAD is the most common arterial cause of …