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he influence of peripheral arterial disease on the systolic blood pressure of the lower extremities was first described by Dr. T. Winsor in 1950 in the American Journal of Medical Sciences. The instrumentation to measure these pressure changes, however, was not readily available at that time. Largely due to research performed at the University of Washington during the 1960’s, the clinical application of mercury strain gauge and Doppler velocity detection was validated and hence, the vascular laboratory was born. The 1970’s brought a call for improved instrumentation from the American Heart Association’s Subcommittee on Peripheral Vascular Disease, resulting in the proliferation of the field of noninvasive vascular testing.

Vascular laboratories in the early years performed multi-segmental lower extremity arterial examinations using a handheld Doppler and a blood pressure cuff. Over time, the progress in technology has provided a number of instruments that can be used in the evaluation of peripheral arterial disease, allowing laboratories any number of examinations that may be performed in a complete arterial assessment of the upper and lower extremities.

What is Primary Arterial Testing?

For accreditation purposes, the ICAVL defines primary testing as the examination most frequently performed in the evaluation of peripheral arterial disease. As previously acknowledged, a complete arterial examination might consist of a variety of testing procedures. The ICAVL Standards require minimum documentation of an ankle-brachial index and waveforms at three or more levels. The minimum requirements for complete examination in accordance with the Standards can be achieved in any one of the following ways:

1. Segmental systolic pressure measurements from three or more levels with segmental continuous wave (CW) or pulsed wave (PW) Doppler or plethysmographic (PVR) waveforms. If Doppler waveforms are performed, sampling must be obtained from at least the common femoral artery, popliteal artery, and distal tibial artery at the level of the ankle. If plethysmographic waveforms are performed, sampling must be obtained from the thigh, calf and ankle.
2. Single level pressures from the ankle (ABI) and waveforms from three or more levels. Again, with CW and PW Doppler waveforms obtained from at least the common femoral artery, popliteal artery and the distal tibial artery at the level of the ankle. PVR waveforms must be obtained from the thigh, calf and ankle.
3. Duplex ultrasonography utilizing gray scale imaging and spectral Doppler waveform analysis. Laboratories utilizing duplex ultrasonography as their primary testing modality must also include measurement and documentation of an ankle brachial index as part of the standard protocol. A limited duplex exam may be performed to obtain only waveforms; however, the laboratory protocol must distinguish the procedure used in a limited and complete arterial duplex if both procedures are performed.

All laboratories applying for ICAVL accreditation must perform one of the three scenarios above as the primary testing modality. Approximately 50 percent of the laboratories applying for accreditation over the past ten years utilize option 1 as their primary testing procedure.

Supplemental Testing

Many laboratories perform supplemental peripheral arterial testing that may provide additional diagnostic information appropriate for specific indications. Standards for supplemental testing have been written; however, a laboratory is not required to perform all testing procedures in order to apply for accreditation. Supplemental exams include, but are not limited to, exercise/stress testing, upper extremity indirect and direct testing, arterial bypass graft surveillance, digit pressures and photoplethysmography, transcutaneous oximetry and laser Doppler.

Although abdominal aorta duplex examination for aneurysm (AAA) is often a high volume examination, it is considered to be supplemental for accreditation purposes. A laboratory cannot obtain peripheral arterial testing accreditation if performing only AAA duplex. However, documentation of this testing volume, technical protocol, diagnostic criteria and case studies are required for the application if performed.

Limited Examinations

A limited examination is one that does not include the minimum required documentation as defined in Section 3 of the Standards. For example, an ABI with ankle waveforms does not meet the requirements of the Standards and is considered a screening examination. As well, a duplex that includes specific arteries to identify a pseudoaneurysm or to identify other abnormalities does not meet the requirements of the Standards. Specific protocols should exist for these testing procedures and should include the specific indications leading to the limited exam. When submitting case studies, the ICAVL requires complete cases for evaluation.

Case Study Selection

Identifying whether examinations are primary or supplemental is the first step to organizing your application. Choosing the representative case studies is paramount to a successful completion of the peripheral arterial testing section.

Case studies are reviewed to evaluate the interpretive and technical quality of the laboratory as a whole and are heavily weighted in the final accreditation decision. The best representative cases from as many medical and technical staff members interpreting or performing peripheral arterial examinations in the laboratory should be included.

Case Study Requirements: First Time Accreditation Applicants

Primary Testing
Laboratories applying for their initial accreditation and performing at least 100 primary examinations per year, must submit five (5) complete representative case studies. One case may reflect normal findings; the other four cases must reflect varying degrees of pathology.

If performed in the laboratory, the following supplemental case studies are additionally required:

Arterial Duplex
If your laboratory performs arterial duplex examinations, and it is not submitted as the primary testing examination, you must submit two (2) representative duplex cases. One case may be normal and one case must be abnormal. These cases can be selected from any duplex procedure performed (i.e., graft surveillance, arterial mapping).

AAA Duplex
Laboratories performing abdominal aorta duplex examinations must submit two cases, one normal and one abnormal.

Upper Extremity
If the laboratory performs upper extremity examinations, two cases must be submitted. Again, one case may be normal and one must be abnormal.

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