Summary Of Evidence

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Analysis of Evidence

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Overview
Non-invasive peripheral arterial vascular studies utilize ultrasonic Doppler and physiologic studies to assess the irregularities in blood flow in arterial systems. These noninvasive peripheral arterial vascular studies include the patient care required to perform the studies, supervision of the studies, and interpretation of study results, with copies for patient records of test results and analysis of all data, including bi-directional vascular flow or imaging when provided.

Diagnostic tests must be ordered by the physician who is treating the beneficiary and the results used in the management of the beneficiary’s specific medical problem. Services are deemed medically necessary when all of the following conditions are met:

1. Signs/symptoms of ischemia or altered blood flow are present;
2. The information is necessary for appropriate medical and/or surgical management;
3. The test is not redundant of other diagnostic procedures that must be performed. Although, in some circumstances, non-invasive vascular tests are complimentary, such as MRA and duplex, where the latter may confirm an indeterminate finding or demonstrate the physiologic significance of an anatomic stenosis (especially in the lower extremity arterial system).

Definitions:

Duplex Scans: Duplex combines Doppler and conventional ultrasound, allowing the structure of blood vessels, how the blood is flowing through the vessels, and whether there is any obstruction in the vessels to be seen. Color Doppler produces a picture of the blood vessel, and a computer converts the Doppler sounds into colors overlaid on the image, representing information about the speed and direction of blood flow. Using spectral Doppler analysis, the duplex scan images provide anatomic and hemodynamic information, identifying the presence of any stenosis or plaque in the arteries. Duplex scans are in real-time.

Physiologic Studies: Functional measurement procedures including ankle/brachial index measurement (ABI), blood pressure and physiologic waveforms, Doppler ultrasound, segmental pressure measurements, blood pressure measurements, transcutaneous oxygen tension measurements, exercise testing, and/or plethysmography. These studies do not involve imaging.

The most common is the ABI test, which compares the blood pressure measured at the ankle with the blood pressure measured at the arm (brachial) using a Doppler stethoscope and blood pressure cuff.

Doppler Ultrasound uses reflected sound waves called physiologic waveforms to evaluate the blood as it flows through an artery. The waveforms bounce off blood cells in a motion that causes a change in the pitch of the sound, called the Doppler effect. These can be measured at a single level, or at segmental (various) limb levels. If there is no blood flow, the pitch does not change.

Exercise testing can be used to analyze the functional significance of vascular disease by reassessing the blood pressure with the Doppler stethoscope after completion of an appropriate amount of stress testing.

Plethysmography is a measurement of the volume of an organ or limb section, or flow rate, in response to the inflation and deflation of a BP cuff.

Transcutaneous oxygen tension measurement may be done in any area of interest, usually the foot or calf. It measures the influx of blood that provides oxygen for diffusion to the skin.

Peripheral Arterial Examinations
In general, noninvasive studies of the arterial system are to be utilized when invasive correction is contemplated, or severity of findings dictates noninvasive study follow up. The latter may also be followed with physical findings and/or progression or relief of signs and/or symptoms. It can be useful in pre-operative evaluation of patients with known arteriosclerotic diseases who will be undergoing surgeries which put them at high risk for vascular complications (i.e. CABG, cranial surgeries etc.). It can be used for surveillance to ensure graft patency post-operatively.

Non-invasive peripheral arterial studies performed to establish the level and/or degree of arterial occlusive disease are considered medically necessary if:

1. Signs and/or symptoms of possible limb ischemia are present; and
2. The patient can be medically managed or is a candidate for percutaneous, surgical, diagnostic, or therapeutic procedures.

Acute ischemia is characterized by the sudden onset of severe pain, coldness, numbness, and pallor of the extremity. Chronic ischemia or critical limb ischemia can have intermittent claudication, pain at rest, diminished pulse, ulceration, and gangrene.

Indications:

1. Signs and symptoms of reduced peripheral blood flow that result in tissue loss, gangrene, or pre-gangrenous changes. Duplex scans are not always needed but may be helpful in defining the regions for arteriography (angiograms), thus limiting the contrast load to the patient.
2. Suspected arterial occlusive disease with symptoms including claudication, rest pain, ischemic tissue loss, aneurysm, and/or arterial embolization. Claudication is defined as pain occurring within 1 block or less of walking and/or of such severity that it interferes significantly with the patient's occupation or lifestyle. Rest pain of vascular disease (typically including the forefoot), is usually associated with absent pulses, which becomes increasingly severe with elevation and diminishes with placement of the leg in a dependent position.
3. Evaluation of grafts or other vascular intervention when signs and symptoms of ischemia, rejection, and/or vascular disease are present.
4. The monitoring of sites of previous surgical interventions, including sites of previous bypass surgery with either synthetic or autologous vein grafts.
5. The monitoring of sites of various percutaneous interventions, including angioplasty,
   thrombolysis/thrombectomy, atherectomy, or stent placement.
6. Follow-up for progression of previously identified disease, such as documented stenosis in an artery that has not undergone intervention, aneurysms, atherosclerosis, or other occlusive diseases.
7. The evaluation of suspected vascular and perivascular abnormalities, including masses, aneurysms, pseudoaneurysms, arterial dissections, vascular injuries, arteriovenous fistulae, thromboses, emboli, various communications between arteries and veins, or vascular malformations.
8. Mapping of arteries prior to surgical interventions.
9. Clarifying or confirming the presence of significant arterial abnormalities identified by other imaging modalities.
10. Evaluation of arterial integrity in the setting of blunt or penetrating trauma with suspicion of vascular injury (including complications of diagnostic and/or therapeutic procedures).
11. Evaluation of patients suspected of thoracic outlet syndrome, with symptoms of positional numbness, pain, tingling, or a cold hand.
12. Allen’s test to establish patency of palmar arch.

Limitations:
Peripheral artery studies may not be considered medically necessary if only the following signs and symptoms are present:

1. Continuous burning of the feet as it is considered to be a neurologic symptom.
2. Nonspecific leg pain and pain in a limb as a single diagnosis is too general to warrant further investigation, unless they are related to other signs and symptoms.
3. Peripheral edema will only be covered with arterial occlusive disease in the immediate postoperative period, in association with another inflammatory process, or in association with rest pain.
4. Absence of peripheral pulses, e.g., dorsalis pedis or posterior tibial, is not an indication to proceed beyond the physical examination unless the absent pulses can be related to other signs and/or symptoms.
5. Screening of the asymptomatic patient is not covered.
6. Ankle-brachial index alone or when part of the physical examination, and not as part of the limited or complete bilateral physiologic studies, is not separately covered.
7. The use of a simple hand-held Doppler device that does not produce hard copy or that produces a record that does not permit analysis of bidirectional vascular flow, is considered to be part of the physical examination of the vascular system and is not separately reimbursable.

Non-covered peripheral arterial study testing methods include thermography, mechanical oscillometry, inductance or capacitance plethysmography, photoelectric plethysmography, differential plethysmography, and light reflective rheography.

Credentialing and Accreditation Standards
The accuracy of non-invasive vascular diagnostic studies depends on the knowledge, skill, and experience of the technologist and interpreter. Consequently, the physician performing and/or interpreting the study must be capable of demonstrating documented training and experience. A vascular diagnostic study may be personally performed by a physician, a certified technologist, or in a certified vascular testing lab.

Services will be considered medically reasonable and necessary only if performed by appropriately trained providers.

1. All non-invasive vascular diagnostic studies must be performed meeting at least one of the following:
   
   1. performed by a licensed qualified physician, or
   2. performed by a technician who is certified in vascular technology, or
   3. performed in facilities with laboratories accredited in vascular technology
2. A licensed qualified physician for these services is defined as:
   1. Having trained and acquired expertise within the framework of an accredited residency or fellowship program in the applicable specialty/subspecialty in ultrasound (US) or must reflect equivalent education, training, and expertise endorsed by an academic institution in ultrasound or by applicable specialty/subspecialty society in ultrasound, or
   2. Has the Registered Vascular Technologist (RVT), Registered Physician Vascular Interpretation (RPVI), or American Society of Neuroimaging (ASN): Neuroimaging Subspecialty Certification; and
   3. Is able to provide evidence of proficiency in the performance and interpretation of each type of diagnostic procedure performed.
3. Nonphysician personnel performing tests must demonstrate basic qualifications to perform tests and have training and proficiency as evidenced by licensure or certification by an appropriate State health or education department. In the absence of a State licensing board, non-physician personnel must be certified by an appropriate national credentialing body.  Appropriate personnel certification includes the American Registry of Diagnostic Medical Sonographers (ARDMS) or Registered Vascular Technologist (RVT) credential; or Cardiovascular Credentialing International’s Registered Vascular Specialist (RVS).
4. Laboratories must be certified by one of the following:
   • Intersocietal Accreditation Commission (IAC),
   • American College of Radiology (ACR),
   • Joint Commission (Vascular lab certification would need to be noted under the main certification either under inpatient or ambulatory care depending on where the test is being performed), or
   • DNV-GL (specific for hospitals only)
   According to which certifying body listed above is selected, that accrediting body’s standards must be followed.
5. Transcutaneous oxygen tension measurement should be performed by personnel possessing the following credentials obtained from the National Board of Diving and Hyperbaric Medicine Technology (NBDHMT): Certified Hyperbaric Technologist (CHT), or Certified Hyperbaric Registered Nurse (CHRN).