Treatment of LEA Disease

Thrombolytic therapy is used to treat…

Extensive acute DVT and acute arterial obstruction by thrombus

BPG

Provides alternate pathway for blood

Require good inflow, adequate conduit, good outflow

Most common BPGs

Aorto-bifem: used to correct distal aortic stenosis and bilateral iliac stenosis

Fem-Fem: used to correct unilateral iliac stenosis

Fem-pop: used to correct unilateral femoral stenosis

Fem-tib: used to correct distal femoral 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

Synthetic grafts

Dacron - synthetic polyester; walls of graft demonstrate SAWTOOTH pattern (not smooth)

Gore-Tex - PTFE; also known as Teflon; demonstrate a double layer wall

All synthetic grafts should demonstrate uniform diameter

Abnormal BGP velocity criteria

<40cm/s at ANY segment in graft

2:1 increase in PSV between two segments or at anastomosis indicates 50% diameter erduction

4:1 increase in PSV between two segments or at an anastomosis indicates >75% diameter reduction (>400cm/s = >75% stenosis)

Abnormal ABI indicated by a DECREASE of >0.15 from last exam

Change from triphasic to biphasic

Complications of BPG

Early graft failure in the first month is due to ERRORS in placement/attachment or graft material malfunction

Reperfusion of the leg via BPG 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 occurs in grafts that are more than 2 years old

Leakage and rupture

Thrombosis

Aneurysm - seen in mature grafts

Vein grafts

Native vein >3mm is preferred, but 2mm and up can be used

Used for extremity, coronary or dialysis graft

GSV, Cephalic, Basilic and SSV commonly used for a vein graft

Pre-Op evaluation:

• Pt in reverse trendelenburg

• R/o the presence of thrombus

• Measure the diameter of vein in multiple locations from upper thigh to lower calf

Reversed saphenous graft

Vein removed and placed in new position in leg

Branches must be ligated

Valves remain and stay OPEN due to gravity

Vein is rotated so the SMALLER more distal end of the native vein is attached above the stenosis and the LARGER more proximal end of the native vein is attached below the stenosis

Smaller diameters end located proximally, larger diameter end located distally

Flow velocities are usually elevated in the now smaller proximal portion and stenosis of the proximal anastomosis is the MOST COMMON complication of…

Reversed saphenous graft

In-Situ vein graft

GSV NOT harvest prior to use

It is detached from the venous system and connected to the diseased artery adjacent to it

Prox GSV connected to the artery proximal to stenosis and distal GSV is connected to the artery distal to stenosis

VALVES MUST BE DESTROYED (can cause stenosis if they remain)

Branches and perforators must be ligated

Most common complication of In-Situ vein graft

AV fistula (b/c branches were not ligated)

Abnormal vein graft criteria

Vein grafts will demonstrate mild thickening of the intima and a nonuniform diameter

In-situ grafts should be evaluated for valve remnants that can cause stenosis and patent branches that can cause AV fistula formation

Reversed vein grafts should be evaluated for patent branches that can cause AV fistula formation

Velocity ratio is the best indicator of graft stenosis; PSV at stenosis divided by the PSV just proximal to stenosis

Abnormal venous graft flow

Decrease in PSV >30cm/s from last exam

Decrease in ABI by more than 0.15 from last exam

Normal venous graft velocity

60-70cm/s

Radial artery

Used as coronary graft instead of saphenous veins b/c it has thicker walls and is similar to coronary artery in caliber

Must test for ulnar artery patency prior to removal (Allen test)

Internal mammary artery

AKA internal thoracic artery

Originates from subclavian artery

Used in TRAM flap breast reconstruction and as coronary graft for left anterior descending artery

Epigastric artery

Superior EA originates from the internal mammary artery and shares anastomosis with the inferior EA
Inferior EA originates from the external iliac artery

Both vessels supply the rectus abdominis muscle that is used in TRAP flap procedure for breast reconstruction

Evaluated to locate the section of muscle with the best perfusion for surgery

PVR amplitude should increase by 50% or more after…

Revascularization

Dampened PVR or PPG waveforms and reduced ankle/foot pressures indicates…

Failure of the BPG

Transducers should be sterilized by soaking them in alcohol for ___________ prior to procedure

30 mins

If an ABI is performed too soon after a procedure for a graft, what can be seen

Artifacts produced by air in the patch or graft

• Can inhibit exam

Monophasic flow with increased diastolic flow may still be identified in the first two months after the graft procedure due to …

Reactive hyperemia

Causes of graft failure <30 days post-op

Technical issues cause failure; improper suture placement, stricture or kinking

Thrombosis is the MOST COMMON cause of acute arterial BPG stenosis/occlusion

1-24 months post op causes of graft failure

Valve stenosis or partial valve remnant in venous graft

Myointimal hyperplasia; MOST COMMON cause of chronic BPG stenosis/occlusion; anastomosis sites are #1 SITE OF GRAFT STENOSIS, related to “over healing” of anast

>24 month causes of graft failure

Usually caused by progression of atherosclerotic disease; less common cause of failure than myointimal hyperplasia

Myointimal hyperplasia of graft

Lower extremity arterial stent eval: <50% stenosis

PSV <180cm/s

Velocity ratio <2.5

Tibial artery velocity >50cm/s

Lower extremity arterial stent eval: 50-70% stenosis

PSV >180cm/s

Velocity ratio >2.5

Tibial artery velocity: <30cm/s

Lower extremity arterial stent eval: >70% stenosis

PSV >300cm/s

Velocity ratio >3.5

Tibial artery velocity <30cm/s

Criteria for synthetic grafts: Normal

PSV <150cm/s

Distal PSV/Prox PSV <1.5

Criteria for synthetic grafts: <49%

PSV: 150-200cm/s

Distal PSV/Prox PSV 1.5-2.0

Criteria for synthetic grafts: 50-75%

PSV 200-400cm/s

Distal PSV/Prox PSV 2.0-4.0

Criteria for synthetic grafts: >75%

PSV >400cm/s

Distal PSV/Prox PSV >4.0

Criteria for vein graft: Normal

PSV <125cm/s

Distal PSV/Prox PSV <1.4

Criteria for vein graft: <49%

PSV 125-180cm/s

Distal PSV/Prox PSV 1.5-2.4

Criteria for vein graft: 50-75%

PSV 180-300cm/s

Distal PSV/Prox PSV 2.5-4.0

Criteria for vein graft: >75%

PSV >300cm/s

Distal PSV/Prox PSV >4.0

Percutaneous transluminal angioplasty (PTLA)/Balloon angio

Balloon tipped catheter inserted into a stenosed artery

Balloon expanded to compress the atherosclerosis and increase the lumen size

Can also be used to deploy a stent

Anticoagulant therapy should be discontinued prior to procedure

Stents are made of Nitinol and are very ECHOGENIC

During procedure, Doppler PTA, DPA or Pero arteries

Use Doppler US to assess stent patency and stenosis

Post PTFE/Angioplasty procedure ultrasound

ABI greater than 0.9 and/or increase of at least 0.25 in the ABI from pre-procedure levels

Eval artery from a few centimeters above the treated area to a few centimeters below treated area

Eval inflow → AT <180cm/s

Eval PTLA site for thombus

PSV <180cm/s and >40 PI

Less than 2.0 velocity ratio

Decrease in PI from treated segments indicated distal disease

Angioplasty failure

Dampened, low-velocity waveforms in the distal arterial tree, no change in post-procedure ABI

Most common cause of restenosis within 1 year of an angioplasty or atherectomy

Myointimal hyperplasia

Intravascular ultrasound

Catheter contains transducer array with multiple elements to provide a circumferential view

Average frequency → 20-40MHz

Can be used to guide procedure or eval stent position after placement

Allows for contrast eval of lumen characteristics as the angio is performed

US guided thrombin injection

Used to treat pseudos

CANNOT be performed on pts on anticoagulant therapy or an associated AVF

Document baseline pedal pulses with Doppler and/or baseline ABIs

Color should not be performed during the procedure

US beam should be PERPENDICULAR to the needle

Thrombin injection should be FAR from NECK

Thrombosis should begin immediately

Re-evaluate pseudo 20-30mins after procedure to confirm pseudo is closed

No change in ABI pre and post procedure

Eval native artery to confirm thrombin did not enter the artery

US guided compression of pseudo

Compression techniques applied to close the stalk and stop the flow

Compression performed io 10 one-min intervals with a re-evaluation of flow with color Doppler after each compression interval

For arterial disease intervention, what pts prep instructions must be provided to the pt?

Requires cessation of anticoagulant therapies

A fem-pop bypass graft is used to treat:

Unilateral distal femoral artery disease

A kissing stent would be used to correct:

Bilateral iliac stenosis

How is the stenosis estimated in a synthetic bypass graft?

Compare the velocities obtained as you move the Doppler cursor through the graft

What is the most common complication of a reversed vein graft?

Stenosis at the proximal anastomosis

What are complications seen in an in-situ vein graft that are not commonly seen with reversed vein grafts?

AV fistula in retained tributaries

Thrombus formation around retained valve cusps

Stenosis formation around retained valve cusps

How is the velocity ratio calculated to evaluate graft patency?

Divide the velocity at the stenosis by the velocity proximal to the stenosis

Whish of the following is a sign of a successful angioplasty procedure on the femoral artery?

A drop in ABI value >0.15

An acceleration time greater than 200ms in the common femoral artery

A velocity ratio <2.0

All of the above

A velocity ratio <2.0

A post-procedure exam following thrombin injection is performed to:

Confirm the thrombus formation within the body of the pseudo, the absence of thrombus formation in the feeding artery, and normal flow pattern and velocity in the feeding artery