How is the test given?
In community screening organizations and services that provide arterial testing to the community are strictly for screening purposes. With these studies, blood pressure cuffs are placed around each biceps and each ankle. Blood pressures are obtained at each area and for each artery in each foot. The high arm pressure in each arm is compared with the highest blood pressure in each foot and an ankle to brachial index (ABI) is calculated. For screening a ratio under 0.90 indicates peripheral arterial disease.
In the office of a vascular specialist the following studies and combination of studies will be performed.
Ankle to brachial index
The first way additional studies are obtained in your doctor’s office is with ankle to brachial index. For ankle to brachial index in the doctor’s office there are other parameters tested and diagnostic criteria.
In addition to what is done by community screening, a great toe to brachial index is also obtained. The toe vessels are less likely affected by hardening of the arteries under the blood pressure cuff.
With these studies, an ankle to brachial index under 0.96 is considered abnormal. The toe to brachial index should be above 0.80 with under 0.60 being the absolute low limit of normal . The toe to brachial index also identifies small vessel disease secondary to diabetes mellitus or a vasculitis (inflammation in your artery). In addition, Doppler waveform analysis of the arm and ankle arteries are obtained. Also, segmental plethysmography is obtained which measures the volume change under the blood pressure cuff with each heartbeat. If the Doppler waveform analysis and/or segmental plethysmography are abnormal and even if the blood pressure is normal or high, you can still have peripheral arterial disease (PAD). You then will need to consider a duplex arterial study of your legs or do multilevel segmental pressures. Duplex means visualization of the arteries with ultrasound and pinpoint directed Doppler analysis in the stenosis and its exit jet. It also includes color flow Doppler looking for areas of color flow turbulence that indicate an area of narrowing that was not seen with plain ultrasound imaging.
The second way if arm and ankle segmental pressures are abnormal is to do multilevel segmental pressures. With this the blood pressure cuffs are placed on the biceps, thighs, calves, ankles, arch of the foot and great toe (or if the great toe is absent then the largest toe remaining) in each foot. Blood pressures are taken with inflation of the cuffs first on each arm, then each great toe and then each ankle, calf and thigh. The cuffs are pumped up above arterial pressure and then deflated and a Doppler is used to document the pulse returns just like a stethoscope can be used on your arm. Segmental plethysmography is obtained over the biceps, thighs, calves, ankles, arch of the foot and great toe. Doppler waveform analysis is obtained in the brachial artery at the elbow, the femoral artery in the groin, the popliteal artery behind the knees and both arteries at the ankles.
The third way your arteries can be studied in the doctor’s office is to perform ankle to brachial pressures as above and perform duplex (visualization in gray scale, color flow and pinpoint position Doppler analysis) of the entire leg or legs. The ankle to brachial index is performed as above and includes plethysmography and Doppler waveform analysis and also includes toe pressures and toe plethysmographic waveforms.
For a duplex arterial study a gel-like substance (which provides for better contact of the scanning head with the skin) is placed over the leg and the soundwaves that travel into the tissue and reflect back to the scanning head are used to make pictures. A pinpoint Doppler can be positioned into a specific area in the artery while viewing it and color is turned on to further identify areas of stenosis and turbulence. The direct Doppler waveforms can then be analyzed to determine the degree of stenosis. This is more specific than the hand-held Doppler for doing multilevel segmental pressures. A limitation of this technique is if the artery is calcified a Doppler signal cannot be obtained from the correct point and is not accurate. Also in this point of the vessel the artery cannot be visualized and color flow cannot be obtained. There is just a shadow.
One other word about toe pressures and plethysmography. The flow is measured by a sensor placed on the tip of the toe that determines when blood flow returns as the cuff is deflated (the blood pressure). This sensor can also determine plethysmographic waveforms.
What other tests can be done?
There are no perfect ways to diagnose all patients. Arteriography in the hospital with a catheter injecting contrast (dye) into the artery and taking serial x-rays to determine the blood flow in the arteries is the gold standard. CT angiography (CTA) and MR angiography (MRA) are the next best to the gold standard. With these exams, however, contrast (dye) can injure the kidneys if you already have kidney damage from diabetes mellitus, hypertension or other causes.
Treadmill exercise stress testing for PAD
If it still cannot be determined for certain what is causing your pain with waking (such as spinal stenosis, lumbar disk disease with radiation to your leg or peripheral arterial disease) then usually treadmill exercise stress testing will determine this.
Arm and ankle blood pressures and routine plethysmography are done before getting on the treadmill. Usually with the treadmill at an incline of 10 to 12 degrees and at 2 to 2.5 mph, you will walk for 5 minutes or until the pain is so severe you cannot walk further. You note where the pain is and if it is the same pain you have been having. You immediately lie down and ankle and arm blood pressures are obtained every 2 minutes. If your arteries are normal, the ankle blood pressures will return to normal at 2 minutes and never longer than 4 minutes. The worse the blockage the longer it takes for the blood pressure to return to normal. If the blood pressures are normal at 2 to 4 minutes, then the problem causing the pain or numbness in your legs is not your arteries.
The only limitation of this test is that the patient must be able to walk on a treadmill.
Post-Occlusive Reactive Hyperemia Testing
If you cannot walk on a treadmill, there is another way of testing, but it is not always completely diagnostic. A blood pressure cuff is placed over the upper thigh and is pumped up above arterial pressure and held for 5 minutes. The cuff is then deflated and blood pressures should return to normal in 30 seconds if your arteries are normal.
The disadvantage of this study is that the cuff may be too painful for some people to tolerate. Also, these cuffs do not occlude blood flow to your buttocks muscles and proximal thigh muscles, but this test still can be very helpful.
Arterial testing for the upper extremities
This is done like multilevel segmental pressures for the legs except the blood pressure cuffs are placed on both arms over the biceps, forearms and index fingers with the segmental plethysmography sensor on the fingertip.
Both arms are compared at all levels for blood pressure, Doppler waveform analysis and plethysmography. Blood pressures can also be compared in all fingers on the same hand but only two fingers at one time. The fingers can be compared at room temperature, after exposure to cold and with warming when checking for cold intolerance—or Raynaud’s— (cold-induced vasospasm).
Finally, the upper extremities can also be studied with duplex Doppler arterial studies and are also used to visualize and study specific areas of narrowing.
We hope the information on these pages is both informative and helpful, but it is intended for education only. Please do note that no web site, no matter how much information is shared, can replace a consultation with your doctor and a vascular specialist. Medical technology and treatment are continually improving and evolving so before making any decision on treatment, it is always advisable to see your doctor first for a comprehensive evaluation of your vascular disease and other medical conditions.
At the Vascular Center of Wichita Falls, we work closely with your other physicians. If you have concerns about your arteries or veins, contact us. A referral is not necessary to make an appointment.