Post-Exercise Test May Help Your Doctor Better Diagnose Your Peripheral Artery Disease (PAD)
A simple test provides a truer sense of blood flow in the legs, providing a better way to test for and grade peripheral artery disease.
Peripheral artery disease (PAD) – also known as atherosclerosis or hardening of the arteries – occurs in the arteries that carry blood to the arms and legs. The arteries slowly become narrowed or blocked when plaque forms inside the artery walls, which can cause damage to the tissues and eventually lead to tissue death.
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The first symptoms of PAD may be leg discomfort, pain or cramping when walking, but is relieved with rest. The risk factors for PAD include smoking, diabetes, individuals 50 and older, African Americans, family history of heart or blood vessel disease, high blood pressure and high cholesterol.
The ankle/brachial index (ABI) is a measurement of the blood pressure in the lower legs compared to the blood pressure in the arms. Vascular surgeon Mehdi Shishehbor, DO, MPH, says post-exercise ABI – blood pressure measurements taken after exercise or walking – may more accurately represent blood flow when patients are experiencing PAD symptoms.
Most patients, Dr. Shishehbor says, present with mild to moderate ABI when using resting ABI alone. But some patients may present with severe disease in post-exercise ABI testing.
“When patients come in complaining of pain in the calf, the test typically performed in most centers in the United State is a resting ABI,” Dr. Shishehbor says. “There is a disconnect because the patient is complaining of symptoms when they walk, but the test for blood flow is performed only at rest. To better understand blood flow and its relation to patient’s symptoms, we should add an exercise test to reflect that.”
Ideally, Dr. Shishehbor says, patients should undergo resting ABI, then walk on a treadmill for five minutes at a 12.5% grade at two miles per hour or until symptoms force them to stop, and then recalculate the ABI post exercise. The combined tests provide a truer sense of blood flow in the legs.
But there are challenges to convincing centers to add post-exercise ABI as a standard of care.
Some centers, Dr. Shishehbor says, have patients perform repetitive pedal plantar flexion technique, which has very comparable results to the treadmill test. Unfortunately, time and insurance constraints prevent many centers from offering the treadmill exercise ABI.
“Patients need to understand when they do these tests at rest, it really reflects blood flow at rest when they have no symptoms,” he says. “As physicians, we have a difficult time understanding what a patient experiences just by talking to them. For some, their pain tolerance may be very high and they can do a lot with little blood flow. Others can do very little with the same amount of blood flow.
“By doing exercise ABI, it offers an objective assessment rather than dealing with subjective issues.”