Peripheral Artery Stenosis Grading | Notes

Walif Chbeir Radiology Notes

December 14, 2016

Peripheral Artery Stenosis Grading by Doppler Ultrasound

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The articles and notes in this website are intended to be used for educational purposes only. The medical informations provided correspond simply to personal notes based on the mentioned bibliography and cannot be guaranteed for accuracy and completeness. Therefore they don’t represent a reference source for scientific articles , neither a medical advice and cannot therefore substitute for the advice of a medical professional. If errors are encountered please send a message to me, so I can make the changes.

* The Peak Systolic Velocity across the stenosis and the Velocity Ratio are the best predictors of peripheral arterial stenosis severity when expressed as % Diameter Reduction.

The Velocity Ratio is the ratio of the PSV at the stenosis compared with the velocity 1–2 cm upstream in a non-diseased segment.

* Normal arteriel caliber

• Triphasic waveform.

• No spectral broadening .

• Normal PSV < 150 cm/sec.

• Velocity Ratio (VR) < 1,5

* 1-19% diameter reduction

• Triphasic waveform with

• Minimal spectral broadening.

• PSV increase < 30% relative to adjacent proximal segment (VR < 1,5)

• Proximal and distal waveforms remain normal* Less than 50% ( 20- 49 %)

• Plaque visualized on grayscale imaging

• Triphasic/biphasic waveforms. Triphasic waveform usually maintained, but reverse flow diminished

. Spectral broadening prominent: Filling in of clear area under the systolic peak

. PSV 150-200.

• 30% to 100% increase in PSV compared with that immediately proximal to the site of

stenosis. VR: 1,5-2

. Proximal and distal waveforms remain normal

* 50 % to 75 % diameter reduction

– Prestenotic segment: Normal

– Intrastenotic segment

. Plaque visualized

. Color flow representation of narrowed flow Channel

. ± Monophasic waveform, loss of reverse flow ( variable) and forward flow throughout cardiac cycle ( si jusqu a 99%).

. Elevated PSV >180 cm/s (200-300).

. More than 100% increase in peak systolic flow velocity compared with that immediately proximal to the site of stenosis. VR 2-4

– Partial post-stenotic turbulence: Systolic spectral broadening

– Distal waveform: Monophasic waveform , Reduced PSV

* 76-99% stenosis– Prestenotic segment: Increased pulsatility

– Intrastenotic segment:

. the real time color Doppler flow will appear as a whitened, color desaturated “flow jet”

. with mosaic color flow extending for several vessels diameters downstream, corresponding to post-stenotic turbulence

. monophasic waveforms

. PSV > 300. EDV > 40. Increased PSV > 4x normal: VR = 4.

– Poststenotic segment: Marked turbulence with Extensive spectral broadening & Simultaneous forward and retrograde velocity spectra during systole & damped waveforms with high-grade obstruction. The spectral broadening (turbulence) may be seen throughout the spectrum if the stenosis is close to the point of measurement; as the distance from the stenosis increases, the spectral broadening is seen in the postsystolic deceleration phase only.

– Distal Waveform: Damped, Monophasic, Reduced.

* As stenosis severity increases to >90% DR, the volume flow through the stenosis trends toward zero, which can produce

. a PSV at the stenosis in a minimally elevated range (100 to 200 cm/s) and

. low velocity (<10 cm/s) “trickle” flow downstream.

* Occlusion

– Occlusion Segment:

. No flow (Absence of color and spectral Doppler signals).

. Intraluminal echoes observed throughout vessel

– Preocclusive thump may be present just proximal to occlusion

– Distal waveform is damped, monophasic with reduced PSV.

• Post Occlusion Reconstitution:. Resumption of flow visualized by color Doppler

. Spectral Doppler flow pattern usually contains both forward and reverse flow

elements (influenced by reentry vessel flow)

– Lengh of occlusion estimated based on distance from exit and re-entry collaterals.

– Some patients will show extensive diffuse disease along the superficial femoral artery but do not show any specific, localised stenoses. This appearance may be severe enough to

produce a significant pressure drop along the vessel, thereby reducing limb perfusion.

– Patients may have several stenoses along the length of the vessel, each of which is not haemodynamically significant but the effects of these are additive, so that there is still a significant drop in perfusion pressure distal to the affected segment.

– The presence of serial stenoses can affect the estimation of the degree of a distal stenosis and a significant proximal stenosis or occlusion will result in a drop in perfusion pressure and velocity which makes application of the PSV and VR problematical.

– Otherwise, the use of velocity ratios in multiple stenoses is somewhat controversial.

Energy Doppler and echo-enhancing agents may allow an estimate of severity of the distal stenosis but if there is clinical doubt, other imaging (CTA, MRA, DSA) should be considered.

* BIBLIOGRAPHY

1– Kelley D. Hodgkiss-Harlowa, and Dennis F. Bandyk, Interpretation of arterial duplex testing of lower extremity arteries and interventions, S E M I N A R S I N V A S C U L A R S U R G E R Y 2 6 ( 2 0 1 4 ) 9 5 – 1 0

2- Simon S. M. Ho, Arterial Occlusive Disease, Peripheral, STATdx ( Ultrasound > Diagnosis > Vascular > Extremities).

https://my.statdx.com/document/arterial-occlusive-disease-periphe-/855f08b5-4624-42d7-abcb- c8ffa9fe5389?searchTerm=Arterial%20Occlusive%20Disease,%20Peripheral,

3- T. Gregory Walker, Femoropopliteal Artery Occlusive Disease, STATdx (Vasculature > Diagnosis > Peripheral Vasculature > Lower Extremity Vasculature ) . https://my.statdx.com/document/femoropopliteal-artery-occlusive-d-/80f5f5fc-1be3-4765-9aa8- bd8c37a1cc84?searchTerm=Femoropopliteal%20Artery%20Occlusive%20Disease.4- Stuart J. Hutchison & Katherine C. Holmes, Lower Extremity Arterial Disease in PRINCIPLES of VASCULAR and INTRAVASCULAR ULTRASOUND, Chapter 5, p 99, ISBN 978-1-4377-0404-4, © 2012 by Saunders, an imprint of Elsevier Inc.

5- Paul L. Allan, The Peripheral Arteries, in Clinical Doppler Ultrasound, Third Edition, Myron A. Pozniak – Paul

6- Cossman et al. Comparison of contrast arteriography to arterial mapping with color-flow duplex imaging in the lower extremities. J Vasc Surg . 1989; 10:522–529.