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Ankle Brachial Index

Introduction

PAD is a narrowing of the peripheral arteries, most common in the arteries of the pelvis and legs. PAD is similar to coronary artery disease (CAD) and carotid artery disease. Narrowed and blocked arteries in various critical regions of the body cause all three of these conditions. Hardened arteries (or atherosclerosis) in the coronary artery region, restricts the blood supply to the heart muscle. Carotid artery disease refers to atherosclerosis in the arteries that supply blood to the brain.

 Problem

  • Many people mistake the symptoms of PAD for something else.
  • PAD often goes undiagnosed by healthcare professionals.
  • People with peripheral arterial disease have four to five times more risk of heart attack or stroke.
  • Left untreated, PAD can lead to gangrene and amputation

PAD Symptoms

For many, the first noticeable symptom of PAD is a painful cramping of leg muscles during walking called intermittent claudication.  When a person rests, the cramping goes away.  This leg pain can be severe enough to deter a person from normal walking.

Some individuals will not feel cramping or pain but might feel a numbness, weakness or heaviness in the muscles.

In patients whose PAD is more severe, insufficient blood flow to the feet and legs may cause a burning/aching pain in the feet and toes while resting. The pain will occur particularly at night while lying flat. For more information, visit our section on critical leg ischemia. Other symptoms include

  • Cooling of skin in specific areas of legs or feet
  • Color changes in the skin and loss of hair
  • Toe and foot sores that do not heal

Lastly, many people are affected by PAD yet they do not have symptoms. These individuals are at a high risk for suffering an early heart attack or stroke. Research has proven that the life expectancy for a person with PAD is greatly reduced. For example, the risk of dying from heart disease is six times higher for those with PAD compared to those without. Therefore, it is important to discuss the possibility of PAD with a health care professional if someone has several of the risk factors for PAD.

PAD Risk Factors

Certain risk factors for PAD can’t be controlled, such as age or having a personal or family history of PAD, cardiovascular disease or stroke. However, patients can control many risk factors including:

  • Cigarette smoking – Smoking is a major risk factor for PAD. Smokers may have four times the risk of PAD than nonsmokers.
  • Obesity – People with a Body Mass Index (BMI) of 25 or higher are more likely to develop heart disease and stroke even if they have no other risk factors
  • Diabetes mellitus– Having diabetes puts patients at greater risk of developing PAD as well as other cardiovascular diseases.
  • Physical inactivity- Physical activity increases the distance that people with PAD can walk without pain and also helps decrease the risk of heart attack or stroke.
  • High blood cholesterol – High cholesterol contributes to the build-up of plaque in the arteries, which can significantly reduce the blood’s flow. This condition is known as atherosclerosis.
  • High blood pressure – Sometimes called “the silent killer” because it has no symptoms.

Solution

PAD diagnosis begins with a physical examination and ABI test.

 

A healthcare provider will check for weak pulses in the legs. The physical examination may include an Ankle-brachial index test.  Ankle-brachial index (ABI) is a painless exam that compares the blood pressure in the feet to the blood pressure in the arms to determine how well the blood is flowing. This inexpensive test takes only a few minutes and can be performed by the healthcare professional as part of a routine exam. Normally, the ankle pressure is at least 90 percent of the arm pressure, but with severe narrowing it may be less than 50 percent.  If an ABI reveals an abnormal ratio between the blood pressure of the ankle and arm, you may need more testing.

Testing Results

The ABI result can help diagnose peripheral arterial disease (PAD). A lower ABI means a patient might have PAD. A slight drop in the ABI with exercise, even if the patient has a normal ABI at rest, means that they probably have PAD.

 

  • No blockage (1.0 to 1.3). An ankle-brachial index number in this range suggests that you probably don’t have peripheral artery disease. But if you have certain risk factors, such as diabetes, smoking or a family history of PAD, tell your doctor so that he or she can continue to monitor your risk.
  • Mild blockage (0.8 to 0.99). If your ankle-brachial index number is less than 1.0, you may have some narrowing of the arteries in your leg. People with an ankle-brachial index of 0.9 or lower may have the beginnings of peripheral artery disease. Your doctor may then monitor your condition more closely.
  • Moderate blockage (0.4 to 0.79). An ankle-brachial index number in this range indicates more significant blockage of your ankle and leg arteries. You may have noticed some pain in your legs or buttocks when you exercise.
  • Severe blockage (less than 0.4). If your ankle-brachial index number is in this range, your leg arteries are significantly blocked and you may have pain in your legs even while resting. An ankle-brachial index of less than 0.4 suggests severe peripheral artery disease.
  • Rigid arteries (more than 1.3). If your ankle-brachial index number is higher than 1.3, this may mean that your arteries are rigid and don’t compress when the blood pressure cuff is inflated. You may need an ultrasound test to check for peripheral artery disease instead of an ankle-brachial index test, or a toe-brachial index test, in which the blood pressures in your arm and big toe are compared.
  • Depending on the severity of your blockage, your doctor may recommend lifestyle changes, medications or surgery to treat peripheral artery disease. Talk to your doctor about your options. You may also need additional imaging tests to see what treatment is best for you.
  • The test may not adequately measure the ankle-brachial index if you have severe diabetes or calcified arteries with significant blockage. Instead, your doctor may need to read your blood pressure at your big toe (toe-brachial index) to get an accurate test result if you have either of these condition

Summary

Treatment options vary and depend on the overall health of the patient and the severity of the diagnosis. The physician should provide the patient with adequate information to help understand all options. The majority of intermittent claudication cases are treated without surgery. Multiple long term studies following a large number of patients with claudication demonstrated that only 1 out of 4 developed worsening symptoms. It also found that only 1 out of 20 patients would require an amputation.  ABI helps physicians to accurately diagnose and provide early treatment for PAD.

Appendix A:

Insurance Coverage

The following is taken from : http://www.summitdoppler.com/docs/REIMBURSEMENT%20for%20the%20PAD%20EXAMINATION.pdf

 

MEDICARE

Non-invasive testing for peripheral arterial disease (PAD) does not have “National Coverage”.  Instead, each individual Medicare insurance carrier determines the local coverage requirements.

 

CPT 93922 Coverage

In general, most Medicare carriers consider an “ABI” exam without blood-flow waveforms to be part of the general physical examination, and hence do not reimburse for “ABI’s” unless waveform analysis is included.  CPT 93922 provides coverage for a single-level lower extremity physiologic study.      When conducted at the ankle, this physiologic study has two components: 1) ABI values and 2) the bi- directional Doppler waveforms from the ankle (PT or DP arteries).      The LifeDop ABI instrument provides a digital printout of the spectral mean Doppler waveform for documentation and reimbursement purposes. Note: Most Medicare carriers prohibit reimbursement for ankle waveforms generated by the older analog strip chart recorders, or for any device that does not provide a hard-copy of the waveform.

 

Medical Necessity

Most Medicare carriers require the health care practitioner to document that the peripheral arterial study was “medically necessary”.  The following are examples of conditions that normally meet the necessary criteria:

  • Claudication of less than one block, or of such severity that it interferes significantly with the patient’s occupation or lifestyle;
  • Rest pain (typically including the forefoot), usually associated with absent pulses, which becomes increasingly severe with elevation and diminishes with placement of the leg in a dependent position;
  • Tissue loss defined as gangrene or pre-gangrenous changes of the extremity, or ischemic ulceration of the extremity occurring in the absence of pulses;
  • Aneurysmal disease; •   Evidence of thromboembolic events; and/or •    Blunt or penetrating trauma (including complications of diagnostic and/or therapeutic procedures).
  • Peripheral arterial studies are usually not reimbursable for the asymptomatic patient (i.e. screening is not reimbursable) under CPT 93922.
  • CPT code and description only © 2004 American Medical Association
  • 1Examples of conditions that may not meet the Medicare requirements for necessity include:
  • Continuous burning of the feet (considered to be a neurologic symptom);
  • “Leg pain, nonspecific” and “pain in limb” as single diagnoses are too general to warrant further investigation unless they can be related to other signs and symptoms;
  • Edema, unless it is in the immediate postoperative period, in association with another inflammatory process or in association with rest pain; and/or
  • Absence of pulses in minor arteries, e.g., dorsalis pedis or posterior tibial, in the absence of symptoms. The absence of pulses is not an indication to proceed beyond the physical examination unless it is related to other signs and/or symptoms.

 

Accreditation Requirements Medicare insurance carriers impose varying degrees of restriction on who may be reimbursed for performing vascular examinations.     Some carriers require only that a person with adequate training and background perform the exam.

 

Other carriers recommend, but don’t require, that the “studies either be rendered in a physician’s office by/or under the direct supervision of persons credentialed in the specific type of procedure being performed or performed in laboratories accredited in the specific type of evaluation.”

The most restrictive Medicare carriers require that the exam be supervised by or performed by a physician, registered technician or specialist (RVT, RCVT, RVS), or by an accredited laboratory.

 

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