MAN0024-DFU • Rev. A • 5/13 5 Wallach Surgical Devices
SECTION 3: Description of Product and Controls
Description of Unit
The Vista ABI is a physiologic exam system designed to aid the clinician in the diagnosis of
peripheral arterial disease (P.A.D.). The unit includes a sensitive, bi-directional Doppler
system, and a pressure system that provides inflation, controlled deflation, and pulse volume
recording (PVR) capabilities. A PPG package (model # L450PG) for obtaining both toe and
limb pressures is available separately. This package includes an arterial photoplethysmograph
(PPG) and a digit cuff.
The Vista ABI is well suited for the ankle brachial index (ABI) examination, the gold
standard for the diagnosis of P.A.D. The ABI compares the systolic blood pressure at the
ankles with the systolic pressure at the brachial arteries. A significantly reduced ankle
pressure results in a low (<0.9) ABI value, which indicates P.A.D. Systolic ankle pressures are
obtained with a pressure cuff and audio Doppler probe. ABI measurements are discussed in
detail in Section 6.
A single level, lower extremity arterial exam (CPT®93922) includes the ABI pressures,
calculated index, and arterial physiologic waveforms. Two types of waveform modalities are
provided on the Vista ABI: continuous-wave (CW), bi-directional Doppler and PVR. Both of
these waveform modalities meet the requirements of CPT 93922. Although both modalities
have significant clinical utility, it is generally not necessary to include both PVR and Doppler
waveforms in reimbursement documentation for CPT 93922 - either one is sufficient.
Waveform analysis is discussed in Section 10.
The Doppler waveform is a graph with a vertical axis (Doppler frequency shift, or pitch)
proportional to the velocity of arterial blood flow. Flow toward the probe is indicated above
the baseline. Flow away from the probe is indicated below the baseline. The 8 MHz,
bi-directional probe is best for superficial vessels and all-around use. The optional 5 MHz,
bi-directional probe is used for deeper vessels and with some obese patients.
Pulse Volume Recording (PVR) is a form of plethysmography, which is an indirect method of
limb volume measurement. A pressure cuff is applied to the limb and inflated to 65 mmHg to
detect the minute fluctuations in limb volume that occur with each heart beat. The PVR
waveform’s contour is a qualitative indicator of presence or absence of peripheral arterial
disease. This type of PVR does not permit calibration by injection of a known air volume and
is used for arterial waveform analysis.
Photoplethysmography (PPG) is an optoelectronic technique for detecting the small changes
of blood volume that occur in the capillary bed. Infrared (IR) light is emitted by the PPG
probe into the skin. Light reflected from the underlying tissue is received by a detector and
converted to an electrical signal. Since blood attenuates IR light at a higher level than the
surrounding tissue, the signal’s pulse contours are determined by the arterial blood supply.
This type of PPG system is primarily for arterial pulse detection.
