URR Treatment of LE Arterial Disease Flashcards
(47 cards)
medical management of extrem arterial disease?
-lifestyle modification: diet, exercise, stop smoking
-medicine: antihypertension meds, aspirin to reduce viscosity of the blood
-surgical: endarterectomy stent, bypass graft
surgical and invasive procedures that require an arterial puncture have an increased risk of hemorrhage when the blood is thinned by?
anticoagulants
Most common bypass grafts?
-aorto-bifem: used to correct distal aortic stenosis and bilat iliac stenosis
-fem-fem: used to correct unilateral iliac stenosis
-fem-pop: used to correct unilateral femoral stenosis
-fem-tib: used to correct distal fem or pop stenosis
-ax-fem: least common; used to bypass multiple sites of stenosis, diseased aorta, or those who cannot undergo aorto-bifem or fem-fem procedures
axillary -fem grafts and fem - fem grafts are used in those patients who are poor candidates for surgery because…
they can be placed more superficially in the body
what are the different kinds of synthetic grafts?
-dacron - synthetic polyester; walls of the graft demonstrate a sawtooth pattern (not smooth)
-gore-tex (polytetrafluorethylene, PTFE), also known as teflon; demonstrate a double layer wall
-all synthetic grafts should demonstrate uniform diameter
abnormal velocity criteria bypass graft?
-<40 cm/s at any segment in the graft
-2:1 increase in PSV between two segments or at anastomosis indicates 50% diameter reduction
-4:1 increase in PSV between 2 segments or at anastamosis indicates > 75%
-abnormal ABI indicated by a decrease >0.15 from last exam
-change from triphasic flow to biphasic flow (or monophasic)
complications of synthetic grafts?
-early graft failure in the first month is usually due to errors in placement/attachement
-reperfusion of the leg via bypass graft can lead to the acute onset of anterior compartment syndrome
-re-stenosis caused by myointimal hyperplasia usually occurs in the first 2 years after placement
-re-stenosis caused by atherosclerosis usually occurs in grafts that area more than 2 years old
-leakage and rupture
-thrombus
-aneurysm (seen in mature grafts)
what are vein grafts?
-> 3mm in diameter preferred, but 2mm and up can be used
-extrem, coronary or dialysis graft
-GSV, cephalic vein, basilic vein, and SSV commonly used for graft
-for pre op patient evaled in trendelenburg position, r/o thrombus, measure diameter of vein in multiple locations from upper thigh to lower calf
what is a reversed saphenous graft?
-vein removed and placed in new position in the leg
-branches must be ligated
-valves remain and stay open due to gravity
-smaller end located prox, larger diameter end located dist
-flow velocities are elevated in the smaller prox portion and stenosis of the prox anastamosis is the most common complication
what is an in-situ vein graft?
-GSV NOT harvested prior to use
-prox GSV connected to the A prox to stenosis and dist to GSV connected to A dist to stenosis
-valves destroyed by valvulatome
-valve remnants can cause stenosis
-branches/perforators must be ligated or AV fistula will form
-AV fistula is the most common complication with this type of graft
abnorm vein graft criteria?
-vein grafts demonstrate mild thickening of the intima and a nonuniform diameter
-in-situ grafts should be evaled for valve remnants that can cause stenosis and patent branches that can cause AV fistula formation
-reversed vein grafts should be evaled for patent branches that can cause AV fistula
-reversed vein grafts should be evaled for patent branches that can cause AV fistula
-velocity ratio best indicator for graft stenosis; PSV at stenosis divided by the PSV just prox to stenosis
-norm velocities within graft average 60-70 cm/s
-abnorm = decrease in PSV > 30 cm/s from last exam
-abnorm = decrease in ABI by more than .15 from last exam
what is the internal mammary artery?
-AKA internal thoracic artery
-originates from subclav a
-used in TRAM flap breast reconstruction and as coronary graft for left anterior descending (LAD) a
what is the epigastric artery
-superior EA originates from the internal mammary artery and shares anastomoses with the inferior EA
-inferior EA originates from the external iliac artery
-both vessels supply the rectus abdominis muscle used in TRAM flap procedure for breast reconstruction
-evaled to locate the section of muscle with the best perfusion for surgery
the radial a is used as a coronary a graft instead of sephaneous veins becuase
it has thicker walls and is similar to a coronary a in caliber
what is the allen test?
-evals patency of palmar arch so the radial a can be harvested for cardiac bypass
-compress radial a just < 1 min while patient clenches fist to increase distal resistance to inflow
-patient releases fist, continue to compress a
-NL - hand returns to normal
-ABNL - hand remains pain, ulnar artery occluded
what is intraoperative duplex monitoring
-used to eval the flow changes during and after graft placement, before wound closure
-surgeon applies higher frequency probe directly to the wound or exposed vessel/graft to assess flow characteristics
-techs control US outside of sterile field
-transducers should be sterilized by soaking them in alcohol for 30 mins prior to procedure
-requires sterile sheath to cover probe
-acoustic gel is used inside the sheath
-ankle/metatarsal/digit PVR, PPG, or CW doppler used to monitor lower extrem flow during recovery
-most distal vessels are preferred for flow eval because it demonstrates the quality of distal perfusion
-PVR amplitude should increase by 50% or more
-ankle pressures may be performed immediately after surgery
-Damped PVR or PPG waveforms and reduced ankle/foot pressures indicate failure of the bypass graft
what is post op exam protocol?
-doppler is preffered
-obtain 2D and PW doppler images of inflow native A, prox anastomosis, body of the graft (take multiple samples to obtain mean graft velocity; average velocity from 3-4 sites in norm segment or graft), distal anastomosis, outflow native A
-PV and phasicity of the flow should be reported
-ABI is usually performed bilat (NEVER place cuff over graft)
-monophasic flow w/ increased diastolic flow may still be identified in the first 2 months
-if stenosis identified, the velocity ratio should be reported with the PSV
-PSV ratio = velocity divided by the PSV in the segment that is immediately prox to stenosis
what are the causes of graft failure when post op is <30 days
-technical issues cause failure; improper suture placement, stricture or kinking
-thrombosis is the most common cause of acute bypass graft stenosis/occlusion
what are causes of graft failure 1-24 months post op
-valve stenosis or partial valve remnant in venous graft
-myointimal hyperplasia; most common cause of chronic bypass graft stenosis/occlusion; anastomosis sites are #1 SITE OF GRAFT STENOSIS related to “over-healing” of the anastamosis
what are causes of graft failure >24 months post op
usually caused by progression of atherosclerotic disease; less common cause of failure than myointimal hyperplasia
bypass graft velocity ratio?
PSV at stenosis/PSV prox to stenosis
what is percutaneous transluminal angioplasty (PTLA)
-aka balloon angioplasty
-balloon tipped catheter inserted into stenosed A
-balloon expanded to compress the atherosclerosis and increase the lumen size
-this catheter based technique can also be used to deploy a stent into the stenosed A
-anticoagulation therapy should be discontinued prior to procedure
-stents are usually made of Nitinol and are very echogenic
-during procedure, doppler should be done on PTA, DPA, or peroneal A
-doppler US used to assess stent patency and stenosis
velocity ratio for post PTLA?
PSV at the stenosis in treated segment/ PSV prox to stenosis
what is intravascular US (IVUS)
-catheter contains transducer array w/ multiple elements to provide circumferential view; slide onto the guidewire that the physician inserts into the vessel
-average 20-40 MHz
-can be used to guide the procedure or eval stent posiiton after palcement
-allows for constant eval of the lumen characterisitcs as the angioplasty is performed
