QVI Case of the
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Patent
History:This
pleasant 68 year old female presents with a long
history of exertional leg pain with absent ankle
pulses. She was therefore referred to the lab for a
bilateral lower extremity arterial duplex exam with
suspcion of peripheral arterial disease. Upon careful
questioning, she also complains of nocturnal
cramps. She denies any pertinent cardiac history and
has never smoked.
Physical Exam:
The femoral, popliteal and DPA pulses are
easily palpable however the PTA is absent bilaterally.
Radial pulses were equal; brachial pressure was 138 mmHg on
the right and 139 mmHg on the left by Doppler. There is
mild edema present bilaterally, right equals left. There
are a number of spider and reticular vein clusters
bilateral lower extremities as well as some small to
moderate sized varicosities. No stasis changes.
Left Leg
Images-





Right Leg Images -




Findings:Pulse
volume recordings were essentially normal
bilaterally. Resting ankle brachial indices (ABI’s) were
as follows: unobtainable PTA and 1.25 DPA on the right
and unobtainable PTA and 1.21 DPA on the
left.
Color flow duplex examination of the
infrainguinal arteries of the bilateral lower extremities
revealed an essentially normal examiniation with only very
minor diffuse disease
through
the distal superficial femoral arteries with estimated stenosis
of 20% or less. However , only two vessel run-off is
identified. The posterior tibial artery could not be
identified despite a diligent search and thought to
be congenitally absent. Additionally, the peroneal
artery is noted to be large in size and the dominant run-off
vessel to the foot. Color flow Doppler demonstrated normal flow
patterns and spectral analysis confirmed normal velocities and
crisply biphasic or triphasic flow throughout. Findings
were virtually identical bilaterally.
Discussion:The awareness of anatomic variations in
popliteal artery branching patterns is important because
certain variations may be limb threatening. Although
popliteal artery branching variations are rare there are two
major variations: a trifurcation or high bifurcation of
the anterior tibial artery and a hypoplastic-aplastic
posterior tibial artery. The latter of the two holds more
clinical significance due to possible compromised distal
blood supply. The actual incidence of a hypoplastic-aplastic
posterior tibial artery ranges between 1.5-11% according to
anatomical studies. In most cases the peroneal artery
was found to be hypertrophic and consequently is referred to
as “great” peroneal artery. According to JCB Grant, "absence
of the posterior tibial artery with compensatory enlargement
of the peroenal artery occurred in 5.2% of 211 limbs." The
peroneal artery usually either joins or replaces the
posterior tibial artery distally and typically continues to
the sole of the foot as the lateral planter artery. In such
a case the medial planter artery is generally found to be
absent. Interestingly
there is a reported correlation of up to 85% between
idiopathic clubfoot and an absent anterior tibial artery,
making it the most common vascular abnormality associated
with idiopathic clubfoot.
When
evaluating patients with duplex imaging, it is important
to be aware of common and even most unusual congenital
abnormalities. Without careful evaluation, this
patient could have been diagnosed with an
occluded posterior tibial artery. Of course, total vessel
occlusion can only be diagnosed when a vessel
is imaged and no flow can be documented. Outflow
collateals at the point of occlusion, inflow collaterals
at the point of reconstitution and a diminished waveform
distal to the occlusion are all diagnostic parameters we
use to make this diagnosis.
QVI Case of the
Month!
For past cases,
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