Arterial (Quiz 4) Flashcards
What are the treatment options for PAD?
medical treatment, surgical reconstruction/bypass grafting, endovascular therapy
The type of intervention depends on what?
disease location and extent
List the five endovascular treatment types.
balloon angioplasty, stent angioplasty, atherectomy, subintimal angioplasty, and stent-graft angioplasty
When is endovascular intervention preferred?
preferred for focal, less than 5cm in length regions of stenosis
What are patient risk factors associated with angioplasty failure?
lesion calcification, occlusions, poor tibial runoff, diabetes mellitus, renal failure
Three ways to surveillance things?
segmental pressures, segmental plethysmography, duplex sonography
What is surveillance used for?
to look for failure of intervention, and progression of disease
perform studies immediately post-procedure
What is PTA?
percutaneous translumenal angioplasty
What is the failure rate for PTA within the first year? And is highest within….
20-40%
the first 6 months
What are the expectations of indirect physiologic testing after treatment?
- in claudicant, ABI should improve to normal
- all patients should show improved ABI of at least >0.2
- in critical limb ischemia patients, toe pressure should have increased to predict healing (at least 30-40mmhg)
- duplex scan may not be needed if ABI is normal
Hemodynamic information provides what?
functional and anatomic assessment
With no stenosis, what velocity information should be expected with duplex imaging?
<50% diameter reduction
PSV of <180 cm/s
Velocity ratio of <2
a normal digital artery waveform
With a moderate stenosis, what velocity information should be expected with duplex imaging?
>50% diameter reduction PSV of 180-300 cm/s velocity ratio of 2-3.5 end diastolic velocity greater than zero monphasic waveform
With a severe stenosis, what velocity information should be expected with duplex imaging?
>70% diameter reduction PSV >300 cm/s velocity ratio of >3.5 end diastolic velocity greater than 45 cm/s dampened, monophasic, and lower velocity
With an occulded artery, what velocity information should be expected with duplex imaging?
no flow will be detected and a dampened, monophasic, low velocity waveform may be present
When should reintervention be scheduled?
greater than 70% stenosis
Because use of angioplasty and stenting doesn’t remove plaque, PSV values may be higher in these areas due to what?
plaque dissection, stent geometry, myointimal hyperplasia, and decreased arterial wall compliance
Angioplasty failure can manifest as occulsion or stenosis. Test findings on in-stent stenosis include:
lumen reduction, elevated PSV values (200-300 cm/s), reduction in ABI, and damped, low-velocity spectral waveform distally
List the three types of grafts.
prosthetic (synthetic) bypass graft, autogeneous vein, and in-situ vein
Describe a synthetic bypass graft.
made of various manufactured materials (PTFE - teflon, Dacron - polyester)
associated with poor long term patency rates
Describe an autogeneous bypass graft.
autogeneous vein is the preferred graft material; has better long term patency rates; must be carefully monitered in short term for early complications and failure
What veins may be used for an autogeneous bypass graft?
cephalic or basilic veins
greater saphenous or lesser saphenous veins
radial artery
What may cause au autogeneous bypass graft to fail?
veins have valves, so graft may be reversed and work against blood flow
Describe an in situ vein for a bypass graft.
the vein being used for bypass is left in its original anatomic position; the branches of the vein must be ligated and valves must be lyzed to allow blood to flow downward; the large end of the vein is anastomosed to the large end of the artery while the small end of the vein is anastomosed to the small end of the artery
What is an orthograde graft?
when the vein is freed from it’s original position and involved lyzing of the valves
What is a retrograde bypass graft?
when the freed vein is flipped so the valves do not need to be removed;
the large end of the vein is anastomosed to the small end of the artery and vice versa
Orthograde and retrograde bypass grafts only relate to which grafts?
autogeneous
Where does the proximal anastomosis usually occur?
at the CFA or SFA
Where does distal anastomosis usually occur?
popliteal artery (above or below knee) or tibial artery
During the first 30 days of the graft, what technical problems are more likely to occur?
retained valve or valve leaflet; intimal flap; problems at anastomotic site due to suture placement; graft entrapment due to improper positioning; and thrombosis due to inadequeate conduit or limited runoff
What problems may occur between 1 and 24 months of the graft?
myointimal hyperplasia (usually at valve site); stenosis at proximal or distal anastomosis
What is the most common cause of graft revision in the time period of 1-24 months?
stenosis at prox or distal anastomosis
What problems may occur after 2 years of the graft?
progression of atherosclerotic disease in inflow or outflow vessels; waveform characteristics must be carefully monitored for changes in diastolic flow, increases in acceleration time, decreases in PSV; aneurysmal dilation
When is the bypass graft routinely surveillanced?
first ultrasound performed within 3 months postoperative; within the first year, surveinllanced every three months; second year surveillanced every 6 months; and annually thereafter
What patients may need more than routine scanning?
those with intraoperative revision, early postoperative revision of thrombectomy, and/or limited venous conduits
What are signs that the graft is not healing?
acute onset of pain; diminished or absent pedal pulses; persistent nonhealing ulcers; recent history of loss of limb swelling; poor physiologic testing results (ABI decrease of more than 0.15 between exams)
When imaging a graft with duplex imaging, what should be imaged with color Doppler and PSV?
inflow artery, proximal anastomosis, mid-graft, distal anastomosis, outflow artery
Why should transverse view be used to image the graft?
to gain an overview of anastomotic sites and graft itself
How is the graft usually anstomosed?
to native vessel in an end-to-side orientation
What is the primary goal of duplex examination of a graft?
to document anatomic and hemodynamic characteristics of bypass graft and adjacent vessels
What are the pitfalls of duplex scanning?
obesity may limit exam; deeply placed grafts may require lower frequencies; dressings, skin staples, and sutures limit access to portions of graft
How does a vein graft appear? PTFE graft?
vein: smooth and uniform walls, intimal-medial layer visible
PTFE: wall should be smooth and uniform, distinct double line appearance
How should plaque be characterized?
homogeneous/heterogeneous, calcification noted, smooth/irregular surface
What is a retained valve?
valve or valve remnant that remain due to incomplete valve disruption during surgery
larger remnants or valve leaflets can produce flow limiting stenosis - appears as bright echoes within graft lumen
What is myointimal hyperplasia?
rapid proliferation of cells into the intimal layer;
it can occur at any point along bypass conduit, but typically occurs in areas where vein has sustained injury or valve sinus
What other abnormalities can be found from the bypass?
dissections, intimal flaps, aneurysms, pseudoaneurysms, hematomas or other perigraft fluid collections
With spectral Doppler, a normal bypass should demonstrate what?
multiphasic waveform with sharp upstroke and narrow systolic peak
high resistance
(reversal component may be absent in early postoperative period; forward flow in diastole may also be in indication of hyperemia or arteriovenous fistula
What is an arteriovenous fistula?
abnormal connection between artery and vein
When does an AV fistula take place?
when branch of GSV is left unligated, creating a connection between venous system and arterial system
blood flow can be diverted into deep venous system
How will spectal Doppler look proximal to the fistula?
low resistance pattern with continuous antegrade flow in diastole
How will the waveform look distal to the fistula?
little or no diastolic flow will be present
A distal stenosis or occlusion (sample taken proximal to the stenosis/occlusion), what will the waveform look like?
blunted, monophasic with no diastolic flow
abnormally high resistance
energy loss, lower velocities
can progress to staccato waveform
What will the waveform look like with a proximal stenosis?
continuous diastolic flow and prolonged rise to peak systole
Analysize velocites with stenosis.
normal: below 150 cm/s
abnormal: >180 cm/s
greater than or equal to 50% stenosis: PSV of 180-300 cm/s and PSV ratio of 2
greater than or equal to 75% stenosis: PSV greater than 300 cm/s and PSV ratio of 3.5
What is the mean graft flow velocity?
additional parameter to access bypass graft patency
calculated by taking average of 3-4 PSV values in nonstenotic graft segments at various levels
What is the normal GFV?
greater than 45 cm/s
What is an abnormal GFV?
less than 40 cm/s consistent with large graft diameter or those with limited outflow
decrease in GFV or more than 30 cm/s indicates pending graft failure
