Pathophysiology
Summary
Peripheral artery disease (PAD) is the atherosclerosis of non-cardiac vessels, prominently targeting the abdominal aorta, common iliac artery, and external iliac artery. Smokers and a history of hypertension have an increased risk for developing PAD. Lesions in PAD most frequently appear in the superficial femoral artery—which derives from the external iliac artery once it passes underneath the inguinal ligament. These lesions tend to be diffuse, bilateral, and impact multiple vessels. The hallmark symptom of PAD is intermittent claudication, an ischemic pain that is triggered by exertion and ameliorated with rest. Specifically, calf claudication results from lesions in the superficial femoral artery. Conversely, buttock pain and erectile dysfunction are associated with lesions in the internal iliac artery or its more distal branches.
Additional clinical features of PAD include cool extremities due to diminished blood flow and hair loss in the affected limb, as the blood supply to hair follicles is compromised. Furthermore, ischemic skin ulcers may form at pressure points, such as the lateral ankle. These ulcers present as deep, ‘punched-out’ lesions with well-defined margins, and their compromised blood flow inhibits bleeding or granulation tissue formation. Among the severe complications of PAD is acute limb ischemia. This can be precipitated by emboli—where proximal atherothrombotic plaques dislodge and migrate to smaller downstream arteries—or by the rupture and thrombosis of atheroma in the involved artery. When acute limb ischemia ensues, the patient experiences a constellation of symptoms including pain, pallor, paralysis, poikilothermia, pulselessness, & paresthesias.
For diagnostic purposes, the ankle-brachial index (ABI) is an instrumental tool. Here, the systolic blood pressure (SBP) of the ankles is divided by the SBP of the upper extremities. A low ABI is indicative of PAD. Patients with PAD have a strong correlation with coronary artery disease and cerebrovascular disease, increasing their susceptibility to MI and stroke. Treatment options include lifestyle changes, aspirin, and cilostazol, a phosphodiesterase inhibitor.
Lesson Outline
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FAQs
Peripheral artery disease (PAD) manifests primarily through atherosclerotic narrowing of non-cardiac blood vessels, most commonly affecting the superficial femoral artery. Its classic symptom is intermittent claudication, an ischemic pain that worsens with physical activity and eases upon rest. Other symptoms can include cool skin, hair loss on the affected limb, and ischemic skin ulcers. In severe cases, acute limb ischemia can cause symptoms such as pain, pallor, pulselessness, paralysis, poikilothermia, and paresthesia.
In PAD, lesions are most commonly found in the superficial femoral artery, which originates from the external iliac artery after it passes under the inguinal ligament. The location of lesions can influence symptoms. For instance, calf claudication is specifically related to lesions of the superficial femoral artery. Lesions affecting the internal iliac artery or more distal arteries are linked to gluteal pain and erectile dysfunction.
Acute limb ischemia in PAD can result from emboli, where proximal atherothrombotic plaques break off and occlude smaller arteries downstream. Another mechanism involves atheroma rupture and thrombosis directly within the affected artery. Acute limb ischemia can cause serious complications, including symptoms like pain, pallor, paralysis, poikilothermia, pulselessness, and paresthesias.
Ankle-brachial index (ABI) is a valuable diagnostic tool for PAD. It is calculated by dividing the systolic blood pressure at the ankle by that of the upper extremity. A low ABI score suggests the presence of PAD.
Treatment for PAD includes pharmacological and lifestyle modifications. Aspirin and cilostazol, a phosphodiesterase inhibitor, are commonly prescribed to minimize clot formation. Lifestyle changes like smoking cessation and blood pressure control are also important in slowing the progression of PAD.
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