Doppler study-Severe stenosis of the lower limb arteries

This 54 year old lady has severe stenosis of the popliteal, posterior and anterior tibial arteries. Having gangrene of the left foot, it was necessary to examine her lower limb arterial tree for the extent of disease. Color and spectral Doppler images of the arteries of the lower limb are shown below:
The normal triphasic spectral Doppler waveform of the major arteries of the lower limb are replaced by biphasic and monophasic waveforms that suggest severe and extensive atherosclerotic stenotic changes.

The femoral artery: biphasic pattern- PSV= 63 cms./sec-(normal= 90 cms./sec) several areas of beading or dropout zones in the color flow observed (due to wall calcification)- s/o moderate stenosis (50- 74 % stenosis) of the left femoral artery. There is also spectral broadening and some degree of dampening of the waveforms.

The left popliteal artery: PSV= 23 cms./sec (normal = 68 cms./sec)- spectral broadening with monophasic pattern - and severe dampening of the flow- increased end diastolic velocity- all suggest severe stenosis (75- 99 %) of the popliteal artery.

The left posterior tibial and anterior tibial arteries also show evidence of severe stenosis (75- 99 %) with marked dampening of flow: (PTA= posterior tibial artery) (ATA= anterior tibial artery):

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Reference: Peripheral vascular ultrasound- Abigail Thrush (see p. 128)

Case-2: A case of moderate left popliteal artery stenosis due to chronic diabetes:

This 60-year-old lady has dampening of flow in the left femoral artery:

see colour Doppler ultrasound is images below: 

in these colour Doppler ultrasound images of the left femoral artery, note the loss of triphasic waveform of the artery in the spectral Doppler images, replaced with a mildly dampened and biphasic flow. The damping of the left femoral artery is more obvious in the lower part of this vessel as it approaches the stenosed left popliteal artery. 

A spectral Doppler ultrasound image of the lower third of the left femoral artery: see below:

The left popliteal artery:

And now we shall see the most severely affected part of the lower limb arterial system, namely the left popliteal artery: the first image shows the stenotic segment of the left popliteal artery- note the very high peak systolic velocity or PSV approaching almost 140 cm/s. The normal peak systolic velocity (PSV) for the popliteal artery should not exceed 68 cm/s. Here, the peak systolic velocity of the left popliteal artery is more than twice the normal suggesting a moderate stenosis at this level.

Transverse section colour Doppler ultrasound image of the popliteal artery shows moderate thickening of wall of the artery with significant stenosis at this level:

A longitudinal section view in colour Doppler of the same stenosed segment of the left popliteal artery:

A spectral Doppler waveform study of the pre-stenotic and post-stenotic segments of the left popliteal artery show moderate dampening of the waveform suggesting significant stenosis in the segment in between:
comparing the peak systolic velocity in the prestenotic and stenotic segments of the left popliteal artery, the stenosed segment shows more than twice peak systolic velocity. (See below):

the rest of the arterial tree below the left popliteal artery confirm the degree of stenosis, in this case due to diabetic atherosclerosis. This is very evident in the left anterior tibial artery, left posterior tibial artery, and the Peroneal artery of the left lower limb. As in the earlier case, this patient too shows moderate to severe dampening of flow in the above-mentioned arteries: ( see colour Doppler ultrasound and spectral Doppler ultrasound images below):

in the above three ultrasound and spectral Doppler waveform images, note the complete loss of tri-phasic waveform replaced by a monophasic dampened flow pattern typical of stenosis higher up, in this case, the left popliteal artery.