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Oct 31

How Poor Leg Circulation Is Detected

Poor leg circulation is a common disease that is unfortunately under-diagnosed in this country. Poor circulation contributes to foot wounds, gangrene, and is a direct cause of leg amputation. Early detection is key to preventing serious complications, and this article will discuss how that is done.

The body requires the oxygen and nutrients in the blood stream in order for tissue to survive. All this is delivered through the blood stream by the arteries, and returned back to the heart by the veins. Unfortunately, arteries are susceptible to blockages that can limit or even cut off the supply of blood going to the feet. This can occur because of plaques that develop on the inner walls of the arteries (similar to heart disease), or due to calcium deposits in the muscle layer of the artery which limits it flexibility. Once the blockage occurs, it can gradually worsen. The body has an ability to re-route some blood through other channels to get to the feet, as there are numerous pathways to the feet in the legs. However, these alternate pathways are not infinite, and eventually the body runs out of options. People at risk for this disease include those with high blood pressure, high cholesterol, diabetes, kidney disease, heart disease, stroke, obesity, advanced age, or those who smoke, amongst others. Early symptoms include thinner foot and leg skin, cooler foot skin temperature, and loss of foot hair. Later stages see the development of foot discoloration to a red, purple, or dark color, and calf or leg pain begins to develop after walking short distances. Severe disease causes painful wounds to develop, toes can turn black, and constant foot or leg pain appears as the tissues begin to die from lack of nutrients. All this can lead to amputation of the leg if the arteries are not repairable. New minimally invasive surgical techniques are available that can repair these artery blockages, in addition to the older techniques of bypassing the blocked segment. However, like all things, these techniques work best when the disease is not as severe. Early detection is the key to preventing severe disease from developing, and physicians have several options available to them to assist with this detection.

Ankle Brachial Index (ABI)

The ankle brachial index is an easy way to get a general picture of how well circulation is getting to the foot. It can be performed in any office, and only takes a few minutes. Blood pressure cuffs and a stethoscope or hand-held Doppler device are used to measure and listen to the blood pressure in the ankle and compare it to the arm, which generally should always have normal circulation. When they are equal, a ratio of 1 is calculated. When the pressure at the ankle is less than the arm, indicating poor leg circulation, the ratio will be less than one. Ratios of 0.6 to 0.9 indicate mild to moderate disease, and those less than 0.5 indicate more severe disease. The ABI is reliable, reproducible, and is a good indicator of leg circulation.

Segmental Pressures and Pulse Volume Recordings (PVR)

This test requires some more specialized equipment, but is available in many physician’s offices as it is portable and relatively inexpensive. Segmental pressures are essentially blood pressure measurements taken at various points over the leg, extending down to the ankle. These pressures function similarly to an ABI, but they can help to generally pinpoint where the actual disease is located along the leg, something an ABI cannot do. PVR is used visually graph the pulsation of the blood in the arteries. A normal graph should have a large incline followed by a steep decline, with a slight leveling of the decline in the middle. When blood flow is poor, the incline and decline flattens out, and in serious artery disease the graph appears to have a nearly flat line. These measurements are taken at the same areas that the segmental pressures are taken, giving the physician a picture into where the flow may be blocked.

Arterial Doppler

Doppler technology uses sound waves bounced off the artery surface to obtain information on how well the circulation is flowing in the leg. The doppler can create several different types of information. Firstly, the doppler creates a distinct audible sound that can be heard as well as graphed visually on a monitor or on paper. Secondly, more sophisticated instruments can create a visual image of the artery, much like an ultrasound for a pregnancy, where blood flow speed can be seen and measured, and color can be added to show the flow direction of the blood more distinctly.

Angiography

Still considered the gold standard for the detection and direct visualization of leg artery blockages, the angiogram is essentially an extended x-ray image of the legs in which radioactive dye is pumped through the leg arteries. Since blood vessels cannot be seen on x-ray, the dye is used to highlight where the blood is going. Where there is blockage, the artery ‘tube’ that the dye illuminates will appear thinner, or even crimp off. This technology can show exactly where the blockage is, and can guide treatment which may even be performed right there during the testing. Unfortunately, the dye can be toxic to the kidneys, and those with kidney disease cannot tolerate this test. It also requires puncturing an artery to insert the dye, which can have complications if there is an issue with clotting or if one is on powerful blood thinners.

Computed Tomography Angiography (CTA)

CT is an advanced x-ray that uses several x-ray exposures to create a three dimensional image of the body’s tissue with the help of computer software. Soft tissue is better seen on a CT than on a regular x-ray, and the image can be rotated and moved to get a better look at various aspects of the body. Unlike regular angiography, the dye used does not have to be placed in an artery. It is injected into a vein, which is safer than an artery. The dye can still cause kidney damage in those with kidney disease, and radiation is still used to obtain the images like an x-ray or standard angiogram. However, the amount of detail obtained by this study is impressive, and can show the leg blood vessel system in its entirety.

Magnetic Resonance Angiography (MRA)

MRAs are an artery specific form of MRI. In this study, the body is subjected to a quick change in its magnetic field. This releases energy that is read by a computer that produces an image of the body’s tissues based on the energy release. The body is not subjected to radiation like in angiography or CTA. A contrast solution is placed in the body through a vein to help the arteries stand out, but this material has less toxicity to the kidney than dye. The image produced is not as defined as CTA, but it is safer for the body overall.

The above studies are a vital part of early prevention of PAD, and regular monitoring of at-risk individuals with at least an annual ABI and PVR or Doppler can help prevent the eventual amputation many serious cases of PAD lead to. If one has a concern for their leg circulation, they should speak promptly with their family doctor, internist, podiatrist, or cardiologist for a more in-depth examination.

Dr. Kilberg provides compassionate and complete foot and ankle care to adults and children in the Indianapolis area. He is board certified by the American Board of Podiatric Surgery, and is a member of the American Podiatric Medical Association. He enjoys providing comprehensive foot health information to the online community to help the public better understand their feet. Visit his practice website for more information.

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