Vascular Diagnostic Testing Part 2 Lower Extremities and Renal

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Vascular Diagnostic
Testing
Optimum Re
Charlotte A. Lee, M.D., DBIM, FLMI
Vascular Diagnostic
Testing
Part 2
Lower Extremities and
Renal Arteries
Charlotte A. Lee, M.D.
Screening
 Venous
and arterial Duplex
 Lower extremity Doppler
 Aortic ultrasound
 Renal artery ultrasound
 Vein and arterial graft
surveillance
 Dialysis access surveillance
Evaluation of:
 Aorta
 Common
femoral artery
 Superficial femoral artery
 Proximal deep femoral artery
 Popliteal artery
 Common and external iliac
arteries
 Tibial arteries
Abdominal Aorta
 Transverse
and longitudinal
views—proximal, mid and distal
aorta
 Transverse view of common iliac
arteries at the aortic bifurcation
 Documentation of aneurysms, if
present—measured outer wall to
outer wall
Abdominal Aorta
Abdominal Aorta
3-D CTA of AAA
Recommended Surveillance
 Less
than 3 cm—no further
testing
 3-4 cm—Every 12 months
 4.0-4.5 cm—Every 6 months
 > 4.5 cm—Referral to vascular
subspecialist
Indications for Repair
Aneurysm
>5.5 cm in
diameter
Expansion of >0.6 to 0.8
cm/year
Renal Artery Stenosis






General population
0.1%
Hypertensive population
4.0 %
HTN and suspected CAD
10-20 %
Malignant HTN
20-30 %
Malignant HTN and renal insufficiency 30-40%
Prevalence increases with age: 7% over 65 yrs.
RAS: Progression of atherosclerotic
lesions
Testing
Gold standard = Invasive
renal arteriography
Indicated when clinical suspicion
high and results of noninvasive
testing inconclusive
Magnetic Resonance
Angiography




Increasingly used as first line screening
test
Shows the renal arteries and perirenal
aorta
Two small studies showed a sensitivity of
100% and specificity of 71-96% when
compared to arteriography
Not useful for diagnosis of fibromuscular
dysplasia that typically affects the middle
and distal portions of the renal artery
CT angiography
Shows renal arteries and perirenal
aorta
 Generally felt to have a sensitivity of
98% and specificity of 94%
 Variable sensitivity in FMD
 Disadvantage: Nephrotoxic

Duplex Doppler
Ultrasonography




Provides both anatomical and functional
assessment of renal arteries
Stenotic lesions are detected by comparing
flow velocities of the renal artery to the
aorta
In patients with high pretest probability of
having RAS , sensitivity and specificity of
98%
Disadvantages: time consuming (2 hours),
highly operator dependent
Fibromuscular dysplasia



Frequently involves
the distal 2/3 of the
renal artery and
branches
Characterized by
“string of beads”
appearance due to
alternating
fibromuscular webs
and aneurysmal
dilatation
Total occlusion
uncommon
Atherosclerosis


Usually involves the
proximal 1/3 of the
main renal artery and
perirenal aorta
In advanced cases,
segmental and diffuse
intrarenal
atherosclerosis
observed, particularly
in ischemic
nephropathy
Renal Vein Thrombosis
Renal Vein Thrombosis—CT
Peripheral Circulation
Arterial Circulation
Ankle-Brachial Index (ABI)
Used to predict the severity of
peripheral arterial disease
 Ratio of the blood pressure in the
lower legs to the blood pressure in
the arms; the BP in the ankle is
normally the same or greater than
the BP in the arms
 Determined by dividing the SBP in
the arteries at the ankle/foot by the
higher of the two SBP’s in the arms

Procedure
Measurements are taken at rest
 Usually repeated after 5 minutes of
walking on a treadmill*

* Even a slight drop in the ABI with
exercise signals a high probability of
PAD


Interpretation of ABI
Ratio of the highest ankle to brachial
artery pressure
 >1.3 is considered abnormal
 <1.0 is considered abnormal
 Abnormal result suggests
calcification of the walls of the
arteries, thus leading to
incompressible vessels

Interpretation of ABI
>1.2 Abnormal vessel hardening
from PVD
 1.0-1.2 Normal range
 0.9-1.0 Acceptable
 0.8-0.9 Some arterial disease
 0.5-0.8 Moderate arterial disease
 <0.5 Severe arterial disease

Limitations
>
1.3 indicates that vessels are
so sclerotic/calcified that they
cannot be compressed for
accurate BP readings
 Does not specifically identify
which arteries are affected
Segmental BP’s
Segmental leg pressure measurements with pulse-volume recordings
Yesenko, S. L. et al. Circulation 2007;115:e624-e626
Copyright ©2007 American Heart Association
Predictability of ABI
 Studies
in 2006 suggest that an
abnormal ABPI may be an
independent predictor of
mortality, as it reflects the
burden of atherosclerosis 1,2
Venous Insufficiency Screening
Venous Valves
Purpose
 To
evaluate the deep and
superficial venous systems for
evidence of valvular
incompetence
Indications
 Pre-op
evaluation
 Venous ulcers
 Lower extremity pain or
heaviness
 Visible varicose veins
 Pain, edema, discoloration
Contraindications and
Limitations
Obesity
 Open draining ulcers
 Severe edema
 Inability to stand for an extended
length of time (patient has to be in
reverse Trendelenberg or standing)
 May be seated for below-the-knee
testing

Direct Method
 Duplex
evaluation for reflux
to include 2-D structure and
motion in real-time, color
flow imaging, and Doppler US
signal documentation
Indirect Method

Photoplethysmographic
sensors—vein is emptied
and the filling time is
recorded (venous refill
time or VRT)
Results
If abnormal VRT normalizes with
application of tourniquet above the
kneeincompetence of GSV
 If VRT remains abnormal, but
normalizes with tourniquet below the
knee, LSV incompetence is suggested
 If still abnormal, deep venous
incompetence is suggested

Deep Vein Thrombosis (DVT)
 Due
to acute or chronic
thrombophlebitis, frequently
due to injury
 Chronic stagnation leading to
phlebothrombosis
Studies
 Duplex
ultrasound
 Venogram—injection of
contrast dye with
radiographic imaging
References
1.
2.
Feringa HH, Bax JJ, van Waning VH et al.
(March 2006). “ The long-term
prognostic value of the resting and
postexercise ankle-brachial index”. Arch
Intern. Med. 166 (5): 529-35
Wild SH, Byrne CD, Smith FB, Lee AJ,
Fowkes FG (March 2006). “Low anklebrachial pressure index predicts
increased risk of cardiovascular disease
independent of the metabolic syndrome
and conventional cardiovascular risk
factors in the Edinburgh Artery Study”.
Diabetes Care 29(3): 637-42.
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