Peripheral artery disease, commonly abbreviated PAD, is a condition in which arteries outside the heart and brain become narrowed or blocked, most commonly because of atherosclerotic plaque. In UK terminology, the condition is generally called peripheral arterial disease. It most often affects arteries supplying the legs and feet, reducing blood flow to muscles and other tissues. The NHS describes PAD as a cardiovascular condition in which fatty deposits in arteries cause reduced blood flow to the legs and feet. PAD is not merely a local leg disorder: it is evidence of systemic arterial disease and is associated with increased risk of coronary heart disease, heart attack and stroke.
The dominant underlying mechanism is atherosclerosis. LDL-containing lipoproteins and other atherogenic particles can become retained in arterial walls, initiating an inflammatory process that leads to plaque formation. Plaque can progressively narrow the arterial lumen and restrict blood flow, particularly when the muscles require substantially more oxygen during exercise. A narrowed artery may provide adequate resting blood flow but fail to deliver enough oxygen during walking, producing the characteristic symptom of intermittent claudication. Advanced disease can cause inadequate blood flow even at rest, leading to more serious tissue consequences.
The classic symptom of PAD is intermittent claudication, in which walking or another form of exertion causes aching, cramping, heaviness or fatigue in the muscles of the leg that improves after resting. The location depends on which arterial segment is affected. Calf symptoms are common when the superficial femoral or popliteal arterial circulation is involved, while disease higher in the arterial tree can produce symptoms in the thigh or buttock. Not everyone with PAD has typical symptoms; some people have atypical leg discomfort or no obvious symptoms despite objectively reduced blood flow. This makes risk-factor assessment and appropriate vascular testing important.
More advanced PAD can cause pain at rest, particularly in the foot, because blood flow is insufficient even when muscles are not exercising. Severe arterial insufficiency can produce non-healing wounds, ulcers, skin changes, tissue loss and, in extreme cases, gangrene. These findings indicate threatened tissue viability and require urgent vascular assessment. A sudden complete blockage can produce acute limb ischaemia, which is different from slowly progressive chronic PAD and can cause sudden pain, pallor, absent pulses, altered sensation and weakness. Acute limb ischaemia is a medical emergency because prolonged severe ischaemia can result in permanent tissue damage.
Smoking is one of the most important risk factors for PAD, while diabetes, high blood pressure, abnormal cholesterol, older age and other cardiovascular risk factors also contribute. Atherosclerosis can affect multiple arterial territories simultaneously, so a person with PAD may also have clinically silent disease in the coronary or cerebral circulation. This explains why PAD is treated as a marker of high cardiovascular risk rather than only as a cause of leg pain. NICE and NHS approaches consequently emphasise comprehensive cardiovascular risk reduction, including lipid management, blood-pressure control, smoking cessation and appropriate antithrombotic therapy.
Diagnosis commonly begins with the medical history and examination, followed by vascular testing when appropriate. The ankle-brachial pressure index, or ABPI, compares blood pressure measured at the ankle with pressure measured in the arm and can identify reduced arterial perfusion. Doppler ultrasound can assess blood flow and arterial structure, while CT angiography or MR angiography can provide more detailed anatomical information when intervention is being considered. The precise investigation depends on symptoms, severity and the planned treatment. A normal resting test does not necessarily exclude exertional disease in every circumstance, so clinical interpretation remains important.
Treatment aims both to improve symptoms and to reduce the risk of cardiovascular events. Regular exercise is a core intervention, and NHS information identifies supervised exercise as an important early management strategy. Smoking cessation is particularly important. Medicines can include statins to reduce LDL cholesterol, antihypertensive drugs when indicated and medicines that reduce thrombotic risk. Severe or disabling disease may require revascularisation, such as angioplasty with or without stenting or bypass surgery, particularly when symptoms remain severe despite initial management or when limb viability is threatened.
PAD is therefore best understood as a manifestation of systemic atherosclerotic vascular disease affecting the peripheral arteries, particularly those supplying the lower limbs. Its significance extends beyond walking symptoms because its presence identifies increased risk of cardiovascular events elsewhere. The disease ranges from asymptomatic arterial narrowing to exertional claudication, rest pain, tissue loss and acute limb-threatening ischaemia. Management combines modification of atherosclerotic risk factors, exercise, appropriate medicines and, when necessary, restoration of blood flow through vascular procedures. NHS guidance specifically notes that treatment of PAD can reduce the risk of other cardiovascular diseases such as heart attack and stroke, reinforcing the importance of treating the underlying vascular disease rather than focusing solely on leg symptoms.
