LE Arterial Stress Testing Flashcards
How does Stress Testing Work ?
why is it necessary?
Create hyperemic state to force vasodilatation: Exercise or Occlusion with a cuff
Well developed collaterals mask disease with normal ABI at rest
Collaterals carrying maximum flow, can not react to increased demand creating positive study
what types of Indirect Physiologic Tests are there? (4)
- Pressure assessment –ABI and/or segmental pressures
- Plethysmography - Pulse volume recording (PVR), Photoplethysmography (PPG)
- Doppler waveform analysis
- Exercise stress test
Why Physiologic Testing vs Duplex?
Short learning curve
Short exam time
Accurate for hemodynamically significant disease (>60%)
- -Negative exam at rest and stress r/o hemodynamically significant disease.
- -High sensitivity and specificity
Provide physiologic information
Equipment is inexpensive
what sizes are the blood pressure cuffs?
Bladder should be 20% wider than limb diameter
thigh = 18 x 36 cm
arms, calf, ankle = 10 or 12 x 23 cm
metatarsal (child-size) = 9 x 20 cm
digit = 2 or 2.5 x 5 cm
Non-uniform limb sizes = variations in pressures.
Bladders over arteries
what size cuffs for 3 and r cuff technique?
Arm cuffs – usually 12 cm (may user 10 cm)
3 cuff tech
HT 18 cm
Calf (below knee) 10 cm (or 12)
Ankle 10 cm (or 12)
4 cuff tech
HT 12cm
LT 12 cm
(same rest of the way down)
what are the doppler pressure sites?
Dorsalis Pedis
easily compressed
harder to locate
Posterior Tibial
Harder to compress
Easier to locate
Essential not to drift off vessel !
what are segmentsal useful for?
where does this study indicate probable inflow dx?
Useful in identifying regions of disease
Toe pressures often useful
This study indicates probable inflow
disease and femoro-popliteal disease
of the left leg.
what do you compare when looking at segmentals?
compare to contralateral limb
compare to adjacent segments
compare to brachial pressure
A 20 mmHg or greater pressure gradient (drop) is significant in the presence of an abnormal ABI
what is an ABI?
Bilateral ankle pressures divided by the higher brachial pressure
Highest ankle pressure value is used for reported ABI
describe ABI levels from normal to ischemic rest pain.
> 1.0 = normal (usually)
Exercise patient if clear claudication symptoms
< 0.96 = abnormal,
exercise patient if borderline
< 0.8 = probable claudication
Exercise patient if borderline
< 0.5 = multi-level disease or long segment occlusion
Exercise patient to determine extent of disease
< 0.3 = ischemic rest pain
Do not exercise patient
what is the ABI value exception for normals?
Brachial systolic pressure below 100 mmHg or above 200 mmHg: ankle pressure may be 25% lower than brachial pressure
Low brachial pressure due to proximal (subclavian) disease
High brachial pressure - HTN
what are teh Pressure limitations for calcified arteries?
diabetics
chronic steroid therapy
renal dialysis patients
segmental pressures unobtainable or excessively high (ABI > 1.4)
what are the methods of stress testing?
what would u do to Stress perfusion to
define extent of disease
how about to test True vascular claudication
or pseudo-claudication ?
use Treadmill
Reactive hyperemia*
Toe raises*
Treadmill
what are the symptoms of spinal stenosis?
Pain and difficulty when standing or walking, aggravated by activity.
Lean forward on shopping cart
Numbness, tingling, hot or cold feelings, weakness or a heavy and tired feeling in the legs.
Clumsiness, frequent falling, or a foot-slapping gait
Substantial ______ provide adequate perfusion to the ankle at rest, thus a normal ABI.
o
With exercise (walking or toe raises) or reactive hyperemia limb blood flow is increased, causing __________.
o
Normal arterial flow will result in _______
o
When _______ lesions are present flow can not be increased adequately through the collaterals, so a pressure drop will occur.
collaterals
vasodilatation
no pressure change or an increase in pressure.
occlusive
what is the purpose of exercise stress testing?
Differentiate borderline normal from abnormal
o
Differentiate true vascular claudication from “pseudo-claudication”.
o
In patients with combined neuropathy and vascular disease, determine which condition is limiting walking.
what are the Indications for Exercise
Intermittent claudicators with normal or boarderline resting ABI
ABI 0.85 - 0.4 to determine extent of disease
(we don’t do if resting ABI is abnormal)
If known neurologic or MS disease and PAD, determine which is limiting walking
what are the contraindications for stress testing?
Ischemic rest pain or ischemic limb ulceration
ABI < .4
Questionable cardiac status
cardiac arrest
Severe pulmonary disease
respirator arrest
Poor ambulators
DO NOT LEAVE THEM ALONE WHILE EXERCISING
how do you do he treatmill stress test?
treadmill speed = 1.5 or 2 mph
10-12 percent grade
5 minutes = standard walking time, or until symptoms occur
Document when symptoms occur and where (calf, thigh, etc)
what do you do post exercise ASAP?
ankle pressures
Some references also do brachial, use the one highest at rest
Some references monitor ABI until they return to baseline
Some references do PT and DP waveforms
Adv: reproduces symptoms, controlled environment that can be quantified and monitored
what are teh 2 main criteria for claudication?
what are the others…
Normal response - ankle systolic pressure increases or stays same & Pressure drop abnormal
Repeat ankle pressure every 1-2 minutes until back to baseline or up to 10 minutes
Usually when a patient is forced to stop due to pain, the pressure will be 60 mmHg or less, this confirms a vascular etiology
If symptoms occur without significant drop in pressure, consider nonvascular cause of symptoms.
what are the 4 post excerise methods?
Method # 1
one bilateral ABI
PVR or Doppler waveforms
Method # 2
serial ABI’s for 5-10 minutes
optional ankle waveforms
Method # 3
Post exercise ABI
Post exercise ankle pressures
Compare to baseline.
Method # 4
Serial ankle pressures for 5- 10 minutes, or until back to baseline
if a pressure is ___ it should increase. otherwise it is ___
Normal
Pressures should increase.
Abnormal
If pressures decrease it is abnormal
