Peripheral Vascular Disease

Background

Peripheral vascular disease (PVD) is a nearly pandemic condition that has the potential to cause loss of limb or even loss of life. Peripheral vascular disease manifests as insufficient tissue perfusion caused by existing atherosclerosis that may be acutely compounded by either emboli or thrombi. Many people live daily with peripheral vascular disease; however, in settings such as acute limb ischemia, this pandemic disease can be life threatening and can require emergency intervention to minimize morbidity and mortality.

NextPathophysiology

PVD, also known as arteriosclerosis obliterans, is primarily the result of atherosclerosis. The atheroma consists of a core of cholesterol joined to proteins with a fibrous intravascular covering. The atherosclerotic process may gradually progress to complete occlusion of medium and large arteries. The disease typically is segmental, with significant variation from patient to patient.

Vascular disease may manifest acutely when thrombi, emboli, or acute trauma compromises perfusion. Thromboses are often of an atheromatous nature and occur in the lower extremities more frequently than in the upper extremities. Multiple factors predispose patients for thrombosis. These factors include sepsis, hypotension, low cardiac output (see the Cardiac Output calculator), aneurysms, aortic dissection, bypass grafts, and underlying atherosclerotic narrowing of the arterial lumen.

Emboli, the most common cause of sudden ischemia, usually are of cardiac origin (80%); they also can originate from proximal atheroma, tumor, or foreign objects. Emboli tend to lodge at artery bifurcations or in areas where vessels abruptly narrow. The femoral artery bifurcation is the most common site (43%), followed by the iliac arteries (18%), the aorta (15%), and the popliteal arteries (15%).

The site of occlusion, presence of collateral circulation, and nature of the occlusion (thrombus or embolus) determine the severity of the acute manifestation. Emboli tend to carry higher morbidity because the extremity has not had time to develop collateral circulation. Whether caused by embolus or thrombus, occlusion results in both proximal and distal thrombus formation due to flow stagnation.

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