M5&6: Peripheral Arterial Part 1 & Indirect Testing Flashcards
risk factors for PAD that can be related to life style
HTN diabetes hyperlipidemia smoking obesity physical inactivity
risk factors for carotid disease related to the heart and blood
homocysteine (a.a produced in liver)
high levels of C-reactive protein (made by the liver)
coronary artery disease
previous TIA or stroke
genetic and/or uncontrollable risk factors for carotid disease
sex - male age hypercholesterolemia genetic predisposition/fam Hx patent foramen ovale radiation
why is diabetes a risk factor for PAD
- atherosclerosis is more common at a younger age in diabetics
- high incidence of occlusive disease in the pop and tibial arteries
- medial wall Ca ++ in the legs is common
- high incidences of gangernous changes leading to amputation
skin changes seen w/ PAD
pallor rubor dependant rubor cyanosis temperature changes ulcers gangrene trophic changes capillary refill time
describe rubor and dependant rubor
dark reddish colour or discolouration from dilated or damaged vessels
dependant: limb takes on pallor when elevated but is abnormally red with hanging dependant
why does cyanosis occur
[ ] of deoxygenated hemoglobin
where do ulcers usually form
over the tibial area
what do trophic changes refer to
shiny, scaly skin, thick toe nails, loss of hair… due to lack of nourishment
what is capillary refill time
why would it be increased
time it takes for colour to return to skin when pressure is applied and then released…. should return immediately
poor arterial blood supply
how are arterial pulses graded
what kind of pulse do aneurysms have
0-4 +
0 = no pulse
4 = bounding
bounding
what may be heard on auscultation w/ PAD
when is it not heard
how it it graded
bruits - abnormal frequency sound due to a significant stenosis…
if vessel is > 90% stenosed because trickle flow happens
1+ - 3+ (mild to severe)
describe claudication
cause
muscle pain that occurs w/ exercise and subsides with rest, intermittent and reproducible
lack of blood supply to a group of muscles
common sites for claudication
hip, thigh, butt, calf
if claudication is experienced, where is the disease location in reference to the affected muscle groups
disease is ALWAYS PROX to the affects muscle groups
(e.g. butt claud. = distal AO/iliac disease
thigh = distal external iliacs/CFA
calf = fem/pop disease)
describe ischemic rest pain
severe pain in the affected limb, usually affects the dorsum (top) of foot and toes, NOT relieved by rest
what does ischemic rest pain indicate
precursor to what
always an indicator of advanced multi-segment disease
limb loss unless theres treatment
when does ischemic rest pain usually occur during the day
why and what can relieve it
night…
limb is not dependent, relieved by lowering the foot or mildly exercising
what is the most sever symptom of PAD
necrosis
describe pseudoclaudication
pain caused by other factors (degenerative joint disease, spinal stenosis, herniated disc)
is pseudoclaudication reproducible w/ exercise testing
no
common patient HX w/ PAD
exercise related claudication rest pain paralysis paresthesia poikilothermia previous ulcerations/gangrene or therapeutic vascular procedures
most common location of obstructive atherosclerosis in LE
other common sites
SFA adductor canal/Hunters canal (distal SFA)… can be hard to see
bifurcations
pop artery
common cause of aneurysm in LE
common locations
trauma or atherosclerosis
AO (AAA)
femoral A
pop A
common cause of subclavian aneurysms
what can they cause
compress of the SA due to thoracic outlet syndrome
embolization to the distal arteries in the hand
what is hypothenar hammer syndrome
aneurysms in the ulnar A due to using hand as hammer…..
diameter of A w/ an aneurysm
how do we document them
-diameter of A increase by at least 50%
- measure AP, outer wall to outer wall, in SAG and TRX
- colour doppler
how does colour doppler help w/ an aneurysm
- helps to outline the thrombus
- shows to and fro flow along the outer wall of the aneurysm
why do we do peripheral arterial duplex testing
- look for stenosis or occlusion (can help w/ pre surgery/intervention)
- evaluate bypass graft
- look for aneurysm
- follow up post surgery or to assess effectiveness of medical treatment
what pathology of the A wall can make a PA assessment hard
calcium deposits which will shadow
an ABI change of what value will warrant a LE, PA scan
decrease in ABI of > 0.15 compared to previous
common reasons for a PA scan of the UE
BP difference > 20 mmHg thoracic outlet syndrome evaluate prior to dialysis access cold sensitivity raynaud's syndrome
how should you document a suspected area of stenosis in the LE
- measure lumen reduction in 2D, especially w/ hemodynamically significant stenosis
- document highest velocity + PW prox and distal to disease
why is it important to have colour gains set appropriately
if gain is too high, colour flow can obscure the true reduction of the lumen
how do we assess UE arteries
record 2D, colour and spectral images in SAG of: innominate A (for R side) prox SCA - probe supraclavicular dis SCA - probe infraclavicular Axillary A brachial A radial A (only spectral) ulnar A (only spectral)
normal PSV for UE arteries
SCA and AXA: 70-120 cm/s
BRA: 50-120 cm/s
RA and UA: 40-90 cm/s
what may be more important than velocity to determines disease in the UE
changes in the waveform
how far should you walk the SV proximal to a suspected stenosis
what should you show distal to the stenosis
within 2 cm
post stenotic turbulence and bruit if present
what velocity ratio can we use w/ PAD
V2/V1 : V2 is the max PSV of a stenosis, V1 is the PSV of the prox normal segment
normal lower extremity arterial waveforms have what characteristics
triphasic
could be biphasic w/o any visualized stenosis… so could be classified as normal… more important is the discovery of CHANGES from triphasic to biphasic
should PSV be relatively uniform throughout an atria segment
yes
mean PSV in LE arteries
external iliac: 120 +/- 22 cm/s CFA: 114 +/- 25 cm/s SFA prox: 91 +/- 14 cm/s SFA dist: 94 +/- 14 cm/s pop A: 69 +/- 13 cm/s
describe a biphasic waveform
- strong forward flow in early systole/sharp upstroke
- loss of flow in early diastole (no reversal)
- decrease of late diastolic flow
describe a monophasic waveform
- decreased pulsatility and PSV
- no reversed flow in late systole
- may or may no have diastolic flow
THINK TARDUS PARVUS - distal to severe stenosis
focal velocity increase of > or = what value indicates > 50% stenosis
> or = double of a prox norm arterial segment
focal velocity increase of > or = what value indicates > 70% stenosis
> or = triple of a prox norm arterial segment
what does a staccato waveform indicate
severe distal stenosis or occlusion
if an artery is completely occluded and hard to identify, what can you use to help
use the flow in an adjacent vein as a guide to identify the occluded
correlative tests for PAD
CTA
MRA
arteriography
medical treatment for PAD
change risk factors exercise antiplatelet medication anticoagulation thrombolysis
surgical treatment for PAD
bypass graft atherectomy resection for aneurysmal disease sympathectomy amputation
endovascular treatment for PAD
angioplasty
stent
intra-arterial directed thrombolysis
what is an ABI
what does it specify
- non-invasive physiologic test that compared systolic BP at the ankles to the systolic BP of the brachial A
- CW waveforms are recorded to support press information
the resulting reduction in blood flow to the extremities at the ankle
why is an ABI referred to as indirect testing
youre not seeing the arteries directly
when will distal arterial flow and BP decreased significantly
when an arterial lumen is. narrowed to a critical level
when should ankle BP cuffs be placed
2-3 cm above the medial malleolus
which vessel in the foot is harder to compress and easier to find
PTA
is the signal of the DPA is damped, retrograde or absent, how should you change your probe position
move to the anterior ankle area, could search for an ATA signal
if you cant identify the DPA, which vessel do you sample instead
where is it located
personal artery
anterior to the lateral malleolus
which vessel in the foot is easy to compress and harder to find
DPA
do we take bilateral BRA pressures
YES
if bilateral arm press is different by > 20mmHg or if the waveforms are different, where should you look
vertebral for SCA steal syndrome
which brachial press do you use for the ABI calculation
highest
why is it good to record the ABI for each artery in the ankle
if you only take the highest, you could misrepresent or miss disease
avg ABI in supine for resting patient
normal ABI
1.1
> 1
when can medial calcification of arteries cause
if ABIs are > 1.3 due to this condition, what should we do
falsely high ABIs
toe pressures
in what type of patients do medial calcification occur
diabetics, patients on steroid medication for renal disease
normal toe/brachial pressure
> 0.75
ABI classifications
> 1.0 normal
0.9 - 1 minimal disease, aysmpt
0.5 - 0.9 claudication usually single level obstruction
<0.5 rest pain, severe, multilevel disease
<0.3 severe ischemia leasing to gangrene
when we are taking an ABI, at which location are we measuring the pressure
the location of the cuff, not the site of doppler interrogation
can you rely on a low pressure reading, but not a high one
yes
what happens to ABIs distal pressures w/ collateralization
collaterals will result in normal distal pressures and waveforms at rest
limitations of ABIs
bandages, trauma, surgery, ulcerations, grafts, ipsilateral side of mastectomy
function of exercise stress testing
determines the functional significance of disease by evaluating the arterial hemodynamics of the lower extremities
protocol for stress testing
pre-exercise BPs and ABIs
re-measure BP and ABIs w/in first minute post exercise
re-take the BPs and ABIs every 2 mins until ankle press returns to w/in 10 mmHg of the baseline press or for 6-12 mins (which ever comes first)
findings of a normal stress test
- little to no drop in ankle BP after 5 mins of exercise… < 20% change
- decrease in post exercise BP should be < 20% of resting press and return to baseline w/in 3 mins post exercise
diagnostic criteria for post exercise BPs and ABIs + recovery time
< 3 mins RT: normal
2-6 mins RT: single level disease
6-12 mins RT: multi-level disease
> 15 mins: severe occlusive disease
what changes in ankle BPs post-exercise indicate significant arterial obstruction
immediate decrease from baseline in post-exercise ankle BPs
can severity of PAD relate to the distant the patient can walk and absolute press drop
yes (more disease = less able to walk and greater press drop)
