Mayo Clinic researchers have developed a new test for diagnosing patients with blood vessel disease in their lower legs that is cheaper, simpler and just as reliable as conventional treadmill testing, according to findings reported in the April 2001 edition of The Journal of the American College of Cardiology.

Between 10 and 30 percent of people over age 70 are affected by a condition called intermittent claudication, which refers to discomfort in the leg muscles when walking. This condition is due to atherosclerosis (plaque deposits resulting in narrowing of the leg arteries) causing inadequate blood flow to the lower leg muscles during exercise. The discomfort occurs each time a person walks a certain distance and goes away after a few minutes of rest, standing still. According to the Mayo Clinic cardiologist who developed the new test, improved diagnosis of claudication holds promise for improved quality of life.

"Circulation problems can produce a significant reduction in quality of life and cause the overwhelming majority of amputations, particularly in patients with diabetes," says Peter C. Spittell, M.D., a Mayo Clinic cardiologist and an author of the study. "If doctors know a patient has narrowed arteries, we have effective treatment that will prevent the loss of a limb. And since atherosclerosis is not just confined to one region of the body, a claudication diagnosis also tips us off that we need to check more closely for heart disease and stroke risks. A large portion of individuals with intermittent claudication do not know they have it, and therefore aren’t being treated. That’s why a new test was needed."

Claudication is diagnosed by dividing the blood pressure reading in the ankle by the blood pressure in the arm. Pressure in the ankle is normally higher than in the arm, so an ankle : brachial index (ABI) that is less than 1.0 indicates blood vessel disease. Since the resting ABI for many patients is normal, conventional testing calls for measuring the ankle and arm pressures after a five-minute walk on a treadmill. Many patients are physically unable to complete the treadmill test, however, and it also requires expensive monitoring equipment.

The new Mayo Clinic test involves measuring the ABI after the patient does up to 50 toe raises next to a wall. "In our study, the tip toe test results correlated exactly with the established treadmill test, but with some significant advantages," says Dr. Spittell. "None of the patients experienced chest discomfort with the tip toe test, but 22 percent were unable to complete the treadmill test because of chest pain or breathing difficulties. And while the treadmill test is conducted in a special lab with expensive monitoring equipment, the tip toe test can be administered in almost any exam room by a nurse practitioner or other health aide, using equipment most physician offices already have."

"This new method can easily reduce expenses for ABI testing by at least 25 percent, and the results are immediate. While family history, high cholesterol, lack of exercise, poor diet and tobacco use are all important risk factors for a heart attack, an abnormal ABI is the single best predictor of future cardiac events. Using the tip toe test will make it easier and more cost-effective for doctors to identify patients at risk and take action to help prevent those events."