Intermittent Claudication

Introduction

Intermittent Claudication (IC) refers to muscle pain in the lower extremities during exercise caused by inadequate oxygen delivery to meet metabolic needs. It commonly arises from Peripheral Arterial Disease (PAD) involving atherosclerotic artery stenosis in the extremities. Pain is typically felt in the thigh, hip, buttock, and calf muscles, triggered by walking and relieved with rest. The severity may correlate with artery blockage. The hallmark is reproducible muscle discomfort during physical activity, often seen in diabetes and smokers.

What Is Intermittent Claudication?

Intermittent Claudication is characterized by pain in the calf (occasionally the thighs and buttocks), triggered by exercise and relieved by rest. It results from the narrowing or blockage of the femoral artery, the main leg artery, caused by atherosclerosis. While blood flow is sufficient at rest, walking intensifies the demand on calf muscles, resulting in cramps and pain due to inadequate blood supply. Resting eases discomfort, but activities like uphill walking can hasten pain onset. Typically seen in those over age fifty, it may occur earlier in smokers, individuals with diabetes, high blood pressure, or high cholesterol. Although the blockage persists, collateral circulation in smaller leg arteries can develop, improving symptoms within six to eight weeks of the onset of claudication.

Intermittent Claudication adversely affects various aspects of life and the ability to work. While its socioeconomic impact remains largely unassessed, it is likely substantial. Importantly, individuals with Intermittent Claudication face an elevated risk of mortality. Unfortunately, many with this condition do not seek medical care. Early diagnosis and effective risk factor management by primary care physicians are crucial in mitigating the mortality risk associated with claudication.

What Are the Causes and Prevalence of Intermittent Claudication?

1. The factors contributing to the onset of intermittent claudication are associated with atherosclerosis.

2. Modifiable risk factors are smoking, obesity, hypertension, dyslipidemia, diabetes, and metabolic syndrome.

3. Non-modifiable risk factors include age, gender, family history, and congenital predisposition. Investigational risk factors include infection, alcohol, C-reactive protein, radiation, reduced adiponectin, homocysteinemia, lipoprotein, and fibrinogen.

4. Additionally, alongside smoking, diminished renal function is considered a significant high-risk factor for the development of intermittent claudication.

Individuals aged 60 and above in the general population, five percent of men and 2.5 percent of women, experience Intermittent Claudication. Among those with peripheral arterial disease, 10 to 35 percent present with the classic form of Intermittent Claudication.

Specific demographics with a heightened incidence of Peripheral Arterial Disease include those over 70, smokers, individuals aged 50 to 69 with diabetes, and those with other atherosclerotic cardiovascular diseases.

Intermittent Claudication results from the narrowing of lower extremity vessels due to atherosclerosis. Oxidative injury initiates atherogenesis by affecting the inner layer of endothelial cells. Endothelial dysfunction leads to the localized deposition of oxidized LDL and the synthesis of pro-inflammatory plaque. Macrophages recruited to the site become foam cells, creating a histologic feature known as a fatty streak.

As the plaque grows, vascular smooth muscles migrate, and collagen deposition forms a fibrous cap. In peripheral arterial disease, plaque formation commonly occurs in the superficial femoral artery, resulting in calf symptoms.

Other locations include the aortoiliac bifurcation, causing hip and buttock pain, and the common femoral artery, leading to thigh or calf claudication. Resting blood flow is comparable to healthy adults, but blood circulation may be reduced to the obstructed areas during exercise. Additionally, individuals with intermittent claudication take longer to recover from physical activity than their healthy counterparts.

What Are the Symptoms of Intermittent Claudication?

Intermittent Claudication typically manifests as lower extremity pain during walking, alleviated by rest, with a gradual progression of symptoms. The pain’s localization depends on the occlusion site, ranging from the buttocks to the lower leg. Aortoiliac disease often presents with buttock pain.

On physical examination, signs of arterial insufficiency, such as a cool limb and diminished pulses, may be evident. The examination should assess femoral, popliteal, dorsalis pedis, and posterior labial artery pulses. Careful differentiation is crucial from other causes of leg pain, including neurogenic pseudo-claudication (spinal stenosis), musculoskeletal pain, and venous claudication with leg swelling and varicosities. Strong pedal pulses generally argue against an Intermittent Claudication diagnosis.

A handheld Doppler device may be necessary when pulses are not palpable. Comparing blood pressure in the arms and ankles is essential; typically, they should be similar, with ankle pressure slightly higher in most individuals. The Ankle-Brachial Index, measured in all individuals, is a valuable indicator of some degree of vascular disease.

How Is Intermittent Claudication Diagnosed?

Diagnosing Intermittent Claudication relies on a characteristic history of muscle pain and cramping after consistent exercise, promptly alleviated by rest. However, conditions like nerve root compression, spinal stenosis, hip arthritis, Baker’s cyst, venous claudication, and chronic compartment syndrome can mimic its symptoms. Pain from nerve root compression often radiates down the back of the leg and is described as sharp or lancinating, sometimes relieved by adjusting the back’s position.

The presence of absent or reduced peripheral pulses or audible bruits supports intermittent claudication diagnosis, but some patients may have normal pulses and no bruits. A low ankle-brachial pressure index also supports the diagnosis, while palpable pulses or a normal resting ankle-brachial pressure index do not rule it out.

If clinical history strongly suggests Intermittent Claudication with a normal Ankle-Brachial Index, an exercise ankle-brachial pressure index is recommended. A substantial drop in ankle pressure after exercise and concurrent symptom development confirms the diagnosis. In cases where the Ankle-Brachial Pressure Index is more than 1.3, potentially due to heavily calcified vessels, a Toe-Ankle Brachial Pressure Index should be calculated.

Standard imaging techniques for intermittent claudication include non-invasive duplex vascular ultrasound, minimally invasive computed tomography, formal peripheral angiography, and magnetic resonance angiography. These modalities help identify the location of diseased vasculature. Aortoiliac disease, termed inflow disease, often manifests with symptoms in the thigh or gluteal muscles. On the other hand, disease below the inguinal ligament typically causes claudication, affecting the calf muscles.

What Is the Treatment of Intermittent Claudication?

Individuals with peripheral arterial disease face a cardiovascular death risk similar to those with a history of coronary or cerebrovascular disease. Managing Intermittent Claudication involves a dual approach: first, focusing on secondary prevention to reduce cardiovascular risks, and second, addressing claudication symptoms for overall symptoms. Secondary risk factor modification involves the following key strategies:

1. Smoking Cessation: Quitting smoking is crucial for reducing cardiovascular risks in peripheral arterial disease. Continuing to smoke increases atherosclerosis progression and the risk of amputation. Despite inconclusive evidence on improving claudication symptoms, the consensus supports smoking cessation as integral to treating intermittent claudication. Nicotine replacement therapy, Bupropion, and Nortriptyline significantly enhance successful smoking cessation.

2. Antiplatelet Drugs: Evidence supports using antiplatelet drugs in reducing major cardiovascular events, arterial occlusion, and the need for revascularization procedures. Various guidelines recommend antiplatelet treatment for peripheral arterial disease patients.

3. Statins: Statins play a dual role by reducing cardiovascular event risks and potentially improving claudication symptoms. Prescribing statins to all eligible patients is recommended unless there is a major contraindication.

4. Diabetes Control: Given the higher prevalence of diabetes in Intermittent Claudication patients, diabetes screening is essential. While control of blood glucose significantly reduces cardiovascular events in diabetes, it does not affect the risk of peripheral arterial disease. Intensive therapy reduces myocardial infarction incidence but not the risk of leg amputation.

5. Blood Pressure Control: Effective hypertension control protects against cardiovascular events. Intensive blood pressure control in diabetic patients is particularly beneficial. However, evidence on blood pressure lowering impact on Intermittent Claudication is limited, and recommendations are lacking.

Symptomatic Treatment:

1. Exercise: Regular exercise has improved total walking distance and maximal exercise time at least thrice a week. Some indications state that supervised exercise may offer greater benefits than non-supervised alternatives.

2. Oral Treatment: Cilostazol, after 12 to 24 weeks of treatment, significantly enhances walking distances compared to placebo. However, common side effects like headache, diarrhea, and palpitations are associated with this drug.

3. Percutaneous Transluminal Angioplasty (PTA): The role of PTA in treating Intermittent Claudication is controversial. While some evidence suggests improved walking distance and quality of life at six months.

4. Transatlantic Inter-Society Consensus Working Group Recommendations: PTA is recommended for patients meeting specific criteria, including single stenoses or external iliac artery, single stenoses or occlusions in the femoropopliteal segment, or multiple lesions without involvement of the distal popliteal artery.

5. Bypass Surgery: The appropriateness of surgery for intermittent claudication varies. For patients with severe symptoms unsuitable for PTA, surgery may be effective but comes with increased risks of morbidity and mortality.

Conclusion

Intermittent Claudication is the initial clinical sign of peripheral arterial disease, often indicative of underlying atherosclerosis. Despite the term ‘peripheral,” this condition’s association with atherosclerosis underscores its significance, with patients facing an elevated risk of cardiovascular death. While managing leg pain is part of symptomatic treatment, the primary emphasis should be reducing overall cardiovascular risk.