Peripheral Vascular Arterial Dopplers

Relevant Social Security Medical Listings

  • Listing 1.10 Amputation of One Lower Extremity
  • Listing 4.12 Peripheral Arterial Disease (Adults)

Type

Objective/Ultrasound (Arterial)

Can SSA Purchase?

Yes. This is not an unusual test for the SSA to purchase. Also, test results should always be considered as part of the evidence of record when provided by a treating doctor.

Purpose

Evaluate the adequacy of arterial blood flow in the arms or legs.

General

The Doppler probe is a transducer that emits high frequency (ultrasonic) sound waves which in turn bounce off of red cells in the moving blood; the probe is placed over the artery after application of a gel to the skin to permit adequate transmission of the sound waves. The returning sound waves are received by a sensor and analyzed electronically; based on the Doppler principle, blood moving toward the transducer causes a shift in reflected sound to a higher frequency and sound reflected from blood moving away from the transducer is shifted to a lower frequency. The greater the frequency difference between sound waves bounced off blood moving toward the transducer compared to that moving away from it, the faster the blood is flowing.

The following diagram shows the major arteries in the lower extremities. The femoral artery is often referred to as the superficial femoral artery to distinguish it from the common femoral and deep femoral arteries.

Contraindications

If exercise Dopplers are done, see Treadmill Stress Testing (TST, TMST), §4.51. There are no contraindications to resting Dopplers.

Technique

Lower Extremity Resting Dopplers

Peripheral vascular disease (PVD) is most frequently characterized by degrees of obstruction (blockage) affecting arterial blood flow to the legs, usually consisting of fatty deposits similar to those that affect arteries in the heart in coronary artery disease. Obstructions affecting blood flow may be in the lower (abdominal) aorta; large pelvic arteries that branch from the aorta (iliac arteries); large arteries of the thigh (superficial or deep femoral arteries); or in the popliteal, posterior tibial (PT), or dorsalis pedis (DP) arteries of the leg and foot. Obstructions in the larger arteries can affect blood flow in the smaller arteries branching from them.

Lower extremity arterial Dopplers can be used to measure the systolic blood pressure in the popliteal artery behind the knee, the posterior tibial artery behind the inner ankle bone, or the dorsalis pedis artery on top of the foot. Most peripheral vascular disease affects the arteries supplying the lower extremity and the most important measurement is that taken on the posterior tibial artery.

To measure the systolic blood pressure in the posterior tibial or dorsalis pedis arteries, a blood pressure cuff is wrapped around the calf (above the point of measurement by the Doppler transducer) and inflated to a pressure that occludes the pulse in the artery. The cuff is then slowly deflated until blood pressure is sufficient to permit flow again under the cuff. Restored blood flow is detected by the Doppler probe and the pressure in the cuff is the same as the systolic pressure. Cuff pressures can be read off in a variety of instruments. The Doppler can also graphically record the waveform shape of the pulse and amplify the returning sounds so that they are audible.

Unfortunately, there is no standardization of protocol for arterial Doppler blood pressure measurements. An acceptable procedure is as follows.

  1. Patients are evaluated while supine, after a 5-minute rest.
  2. A blood pressure cuff is placed on each arm and ankle
  3. A Doppler transducer is used to detect each pulse, by inflating the cuff to 10 mm Hg above systolic pressure and deflating it at 2 mm Hg per second.
  4. The first reappearance of the pulse was taken as the systolic pressure. The systolic pressure is taken a second time, and the two values were averaged. If any pair of values differs by more than 6 mm Hg, repeat pressures are taken, and the average of the most consistent pair was used for analysis and calculations.
  5. Pressures are obtained in the following order: right arm brachial artery, right DP, right PT, left DP, left PT, and then left arm.

To measure the systolic blood pressure in the popliteal artery behind the knee, a larger cuff is used and wrapped around the thigh above the popliteal artery. Otherwise, the principle is the same.

Systolic blood pressure is also measured in the brachial artery of the arm, in order to compare it to the lower extremity blood pressure.

Upper Extremity Resting Dopplers

Measurement of systolic blood pressure in arteries of the upper extremity (subclavian, brachial, radial, ulnar) is performed using the same general technique as described for the lower extremities. Obstructions in the upper extremities are much less common than in the legs.

Exercise Dopplers

Exercise Dopplers may be done to assess the impact of PVD on the functional capacity of the patient, especially when symptoms of claudication are severe compared to those that would be expected in a patient with only a moderate resting Doppler abnormality.

An exercise Doppler study involves the patient walking on a treadmill at 2 mph on a 10 or 12 percent grade for 5 minutes. Resting Dopplers are done before the exercise test, for comparison with the post-exercise values. Continuous EKG, blood pressure, and other vital sign monitoring should be done during this testing.

Complications

If exercise Dopplers are done, see Treadmill Stress Testing (TST, TMST). There are no complications to resting Dopplers.

Interpretation

The systolic blood pressure in the ankle (posterior tibial) artery is divided by the systolic pressure in the arm (brachial) artery. The systolic pressure is normally about 30 mm Hg higher in the legs than in the arms. Therefore, an ankle/brachial (A/B) ratio of systolic blood pressures greater than 1.0 is expected when blood flow to the lower extremities is normal. When significant peripheral vascular disease is present, the A/B ratio will be less than 1. Although the Social Security Administration and many physicians use the A/B ratio to specifically refer to use of the posterior tibial artery, some practitioners use “ankle” in a broader sense that could mean either an A/B ratio using the posterior tibial artery or an A/B ratio calculated using the dorsalis pedis artery. Therefore, it is important to have not to make assumptions about how a test was done without the actual report.

Very severe PVD is present when the A/B ratio is less than 0.5, and any ischemic ulcers present will not heal. The ankle/brachial ratio is frequently referred to as the Doppler Index (DI). Although a Doppler study could be obtained for any lower extremity artery, it is the ankle artery that must be used for an A/B ratio. On physical examination of a normal person the pulse of the posterior tibial artery can be felt behind the inner bone of the ankle (medial malleolus). Moderate arterial insufficiency of blood flow to the legs is indicated by DI values of 0.5 to 0.7. Mild insufficiency is present when the DI is between 0.7 and 0.9. The dorsalis pedis artery runs on top of the foot, but is smaller and more difficult to obtain an accurate a Doppler reading on or feel a pulse.

Normal resting DI values are 0.9 to 1.0 or greater, but there is no universal agreement on the lower cut-off point that should be considered abnormal. If the resting DI is less than 0.8, there is almost always some degree of arterial disease. Generally speaking, the normal resting DI in women is 0.07 lower in women than men. Part of this difference can be attributed to the fact that for each 10 cm in height there is a 1 mm Hg increase in ankle pressure. However, there is an additional unknown factor accounting for the remainder of the difference. In both sexes, the dorsalis pedis DI is normally lower than the posterior tibial artery DI by an average of 0.04. The right leg has a normal resting DI on average of 0.04 higher than the left leg, possibly because it is the leg usually measured first. Most people with significant occlusive peripheral arterial disease have at least two-vessel involvement in the same leg, so that there can be expected a decrease in the DI for both the dorsalis pedis and posterior tibial arteries. Isolated disease in the posterior tibial artery alone is unusual.

Exercise Dopplers refers to systolic ankle Doppler pressures taken after treadmill exercise. The importance of exercise Dopplers lies in the fact that decreases in peripheral blood flow to the lower extremities may be present with exercise that at not present at rest. If the ankle systolic pressure decreases by at least 50 percent with exercise and requires at least 10 minutes to return to pre-exercise values, very severe PVD is present. Such a patient would have an extremely limited exercise capacity. Resting Dopplers showing a Doppler Index of 0.8 or higher are not likely to result in an abnormal exercise Doppler test.

Comments

Doppler ultrasound can provide information about blood flow, but does not permit imaging of arteries or the occlusions (usually atherosclerotic fatty deposits) within them that may impair such flow. Doppler ultrasound does not permit evaluation of small artery disease, as is present in many individuals with diabetes mellitus. It is also well-known that peripheral arterial disease and coronary artery disease frequently occur together. Asymptomatic coronary disease is even more prevalent in diabetics than in the non-diabetic population. However, the ABI should not be used to screen out the likelihood of coronary artery disease in asymptomatic diabetics, including those with type 2 diabetes. Many diabetic individuals have normal ABIs and significant coronary artery disease.

Examples

Example 1

Peripheral Vascular Exercise Dopplers
Patient:
Sex: Female
Age: 63
Height: 62 inches
Weight: 137 lbs.
Vascular History:
Smoker: Yes, current
Hypertension: Yes
Hyperlipidemia: Yes
Angina: No
Myocardial Infarction: No
Obesity: No
Diabetes mellitus: Yes
Venous abnormalities: No
Arterial Vascular surgery: Aorto-iliac bypass grafting two years previously.
Symptoms:
Pre-exercise: History of pain with numbness across buttocks that works its way down to ankles.
Post-exercise: Severe pain starting in right buttock extending down to calf on the right side.
Pre-exercise Clinical Examination:
Femoral pulses: normal bilaterally
Popliteal pulses: normal bilaterally
Posterior tibial (ankle) pulses: normal bilaterally
Dorsalis pedis pulses: normal bilaterally
Skin color normal.
No ulcerations.
Feet warm.
No edema.
Pre-Exercise Data Summary:
Brachial Arterial Pressures:
Right arm: 138/68 Left arm: 134/68
Lower Extremity Arterial Systolic Pressures:
Superficial Femoral (thigh): Right 145, Left 156
Popliteal: Right 144, Left 173
Posterior tibial (ankle): Right 138, left 137
Dorsalis Pedis: Right 95, left 83
Ankle/Brachial (A/B) Index: Right 1.00, left 0.993
Exercise: Treadmill, 2.5 mph, 12% grade, duration 2:16
One Minute Post-Exercise Data Summary:
Brachial Arterial Pressures (systolic):
Right arm: 164 Left arm: 158
Lower Extremity Arterial Systolic Pressures:
Right posterior tibial (ankle): 178
Left posterior tibial (ankle): 186
Ankle/Brachial (A/B) Index: Right 1.09, left 1.13

Comments

The arterial vascular study on this patient demonstrates normal pressures throughout. The post-exercise recordings are completely within normal limits.

Impression

Normal peripheral arterial exercise Doppler study with excellent flows into the ankles. I would think that this patient’s numbness and pain are not due to peripheral arterial disease.