VASCULAR TESTING

This page describes some of the ways that can determine how good the patient's circulation is.

Doppler

The Doppler test uses a special probe is pointed over an artery to test blood flow in an artery.

How does it work? If you've ever noticed that the pitch of a car engine goes up as it approaches you, then goes down as it moves away from you, you've experienced the Doppler effect. The reason for the effect is that sound waves don't move all that fast (at least compared to, say, light), so adding the speed of an automobile to the speed of sound causes sound waves to become compressed, which raises their pitch. Similarly, if the automobile is moving away from you, the car's speed deducted from the speed of sound will cause the sound waves to be more widely spaced, and the pitch goes down.

The Doppler test works the same way. The probe of the machine shoots sound waves at the red blood cells in the artery, and the speed of the red blood cells is measured by noting how quickly the sound waves bounce back off the blood cells towards the Doppler probe. The test works because if there is vascular disease, the blood vessels are more constricted, which causes the speed of the red blood cells to go down, giving a different read-out on the Doppler machine.

The test is completely painless.

Diabetics, smokers, the elderly, and anyone else with circulation concerns should be considered for this sort of vascular testing.

Koven SmartDop 20

A PPG or Photoplethysmograph is another non-invasive test. Unlike the Doppler, the PPG measures the health of the tiny vessels. It is done by applying a small probe to the tips of a toe. It is painless.

An ABI or Ankle-Arm Index or Ankle-Brachial Index tests how good the large vessels that head down towards the foot. The patient's blood pressure is taken at each arm and at each ankle, and the ratios are compared. People with poor circulation in the vessels that head towards the foot will have altered ABI's. For example, an ABI of .96 or above is normal. An ABI of .31 to .95 will have pain with activity. An ABI of .25-.3 will have pain at rest. And an ABI under .3 will have a tendency towards gangrene. Most podiatric physicians will generally not perform elective surgery once the ABI nears .75.

Toe pressures are like a blood pressure test for the toes. Like with the ABI, large pressure differences between the toe pressure and the arm pressure signify disease.

Angiography is a study where a dye is injected into a blood vessel and a special X-ray is taken. While blood vessels are typically invisible to X-ray, the dye is visible. Any areas where the vessel is constricted, there is less dye seen on the X-ray. This test may be done when the level of blockage needs to be identified.

We have vascular testing equipment on-site at the Achilles Foot Health Centre.