Peripheral Arterial Occlusive Disease Clinical Presentation

Intermittent claudication typically causes pain that occurs with physical activity. Determining how much physical activity is needed before the onset of pain is crucial.

• Typically, vascular surgeons relate the onset of pain to a particular walking distance in terms of street blocks (eg, 2-block claudication). This helps to quantify patients with some standard measure of walking distance before and after therapy.
• Other important aspects of claudication pain are that the pain is reproducible within the same muscle groups and that it ceases with a resting period of 2-5 minutes.
• Location of the pain is determined by the anatomical location of the arterial lesions. Peripheral arterial occlusive disease (PAOD) is most common with the distal superficial femoral artery (located just above the knee joint), which corresponds to claudication in the calf muscle area (the muscle group just distal to the arterial disease).
• When atherosclerosis is distributed throughout the aortoiliac area, thigh and buttock muscle claudication predominates.
• The perceived significance of claudication is variable. Most patients appear to accept a decrease in walking distance as a normal part of aging. Investigators report that 50-90% of patients with definite intermittent claudication do not report this symptom to their clinician.
• Atherosclerosis is a systemic disease process. Patients who present with claudication due to PAOD can be expected to have atherosclerosis elsewhere. A full assessment of the patient's risk factors for vascular disease should be performed.
• The risk factors for PAOD are the same as those for coronary artery disease or cerebrovascular disease and include diabetes, hypertension, hyperlipidemia, family history, sedentary lifestyle, and tobacco use.
• Smoking is the greatest of all the cardiovascular risk factors. The mechanism by which smoking causes or accentuates atherosclerosis is unknown. What is known is that the degree of damage is directly related to the amount of tobacco used. This finding was recently documented in women, in whom smoking was found to not only be a potent risk factor for symptomatic peripheral arterial disease, but also subclinical systemic inflammation.^[2] Counseling patients on the importance of smoking cessation is paramount in PAOD management.

Essential to the physical examination of a patient with claudication is a complete lower extremity evaluation and pulse examination, including measuring segmental pressures, as depicted in the image below. Atrophy of calf muscles, loss of extremity hair, and thickened toenails are clues to underlying peripheral arterial occlusive disease (PAOD).

• Palpation of pulses should be attempted from the abdominal aorta to the foot, with auscultation for bruits in the abdominal and pelvic regions. This can be difficult in a patient who is obese, in whom palpable pulses may be hidden under a deep subcutaneous layer.
• Except in the rare case of a congenital absence of a pulse (eg, persistent sciatic artery), the absence of a pulse signifies arterial obstruction proximal to the area palpated. For example, if no femoral artery pulse is palpated, significant PAOD is present in the aortoiliac distribution. The same can be said if no palpable popliteal artery pulse is present because of existing superficial femoral artery occlusive disease.
• Patients who report intermittent claudication and have palpable pulses can present a clinical dilemma.

  • If the history is consistent with typical claudication symptoms, the clinician can have the patient walk around the office (or perform toe raises) until the symptoms are reproduced and then palpate for pulses.
  • The exercise should cause the atherosclerotic lesion to become significant and should diminish the strength of the pulses distal to the lesion.
• When palpable pulses are not present, further assessment of the circulation can be made with a handheld Doppler device.

  • An audible Doppler signal assures the clinician that some blood flow is perfusing the extremity.
  • If no Doppler signals can be heard, a vascular surgeon should be immediately consulted.
• Pressure measurements can be performed to gain objective data on the circulatory status.

  • To obtain an accurate pressure reading, (1) place the pneumatic cuff around the ankle, (2) position the Doppler probe over the dorsalis pedis or posterior tibial artery, and (3) inflate the cuff to a reading above the systolic pressure and deflate. The systolic tone at the ankle vessel is the pressure recorded.
  • A healthy person has no pressure drop from the heart to the ankle. In fact, the pressure at the ankle may be 10-20 mm Hg higher due to the augmentation of the pressure wave with travel distally.
  • In patients with claudication, the measured pressure is diminished to some extent, depending on the severity of PAOD.
• A useful tool in assessing a patient with claudication is the ankle-brachial index (ABI), which is calculated as the ratio of systolic blood pressure at the ankle to the arm.

  • Determining the ABI provides an assessment of the impact that the PAOD is having on the patient. A normal ABI is 0.9-1.1. However, any patient with an ABI less than 0.9, by definition, has some degree of PAOD. The ABI decreases with worsening PAOD.
  • A 2011 study investigated whether subjects not considered to be at high risk for cardiovascular disease based on their Framingham Risk Score had abnormal ABIs. As determined based on Framingham Risk Score, 56.3% of subjects in the study were at low risk for cardiovascular disease, 25.8% were at intermediate risk, and 17.9% were at high risk. However, a relatively low percentage of participants (approximately 12%) had a low or intermediate Framingham Risk Score and still had an had an abnormal ABI.^[3]
  • One area of inaccuracy with the ABI is in patients with diabetes who have PAOD. Peripheral vessels in patients with diabetes may have extensive medial layer calcinosis, rendering the vessel resistant to compression by the pneumatic cuff. These patients should be referred to a vascular laboratory for further evaluation.