ACR Appropriateness Criteria®
Clinical Condition: Follow-up of Lower Extremity Arterial Bypass Surgery
Variant 1: Claudication/suprainguinal graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Physiologic noninvasive tests |
9 |
|
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
INV, angiography (DSA) |
8 |
Indicated if noninvasive studies are abnormal. Not for screening. |
MRA |
6 |
|
CTA |
5 |
Although not yet supported by studies, MDCTA is emerging as a widely used and reliable noninvasive study in this clinical setting. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 2: Claudication/infrainguinal vein graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Physiologic noninvasive tests |
9 |
|
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
INV, angiography (DSA) |
8 |
Indicated if noninvasive studies are abnormal. Not for screening. |
MRA |
6 |
|
CTA |
5 |
Although not yet supported by studies, MDCTA is emerging as a widely used and reliable noninvasive study in this clinical setting. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 3: Claudication/infrainguinal prosthetic graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Physiologic noninvasive tests |
9 |
|
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
INV, angiography (DSA) |
8 |
Indicated if noninvasive studies are abnormal. Not for screening. |
MRA |
6 |
|
CTA |
5 |
Although not yet supported by studies, MDCTA is emerging as a widely used and reliable noninvasive study in this clinical setting. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 4: Threatened limb/suprainguinal graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Ankle-brachial indices (ABI) |
9 |
|
INV, angiography (DSA) |
9 |
Indicated if noninvasive studies are abnormal. Not for screening. |
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
Other physiologic noninvasive tests |
4 |
|
MRA |
4 |
|
CTA |
3 |
|
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 5: Threatened limb/infrainguinal vein graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Ankle-brachial indices (ABI) |
9 |
|
INV, angiography (DSA) |
9 |
Indicated if noninvasive studies are abnormal. Not for screening. |
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
MRA |
6 |
In selected cases, to determine patency of distal vessels. |
Other physiologic noninvasive tests |
4 |
|
CTA |
2 |
|
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 6: Threatened limb/infrainguinal prosthetic graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Ankle-brachial indices (ABI) |
9 |
|
INV, angiography (DSA) |
9 |
Indicated if noninvasive studies are abnormal. Not for screening. |
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
MRA |
6 |
In selected cases, to determine patency of distal vessels. |
Other physiologic noninvasive tests |
4 |
|
CTA |
2 |
|
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Variant 7: Asymptomatic/infrainguinal vein graft.
Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
Physiologic noninvasive tests |
8 |
|
US, Duplex Doppler with color, arterial |
8 |
Color Doppler with waveform evaluation of entire graft. |
CTA |
5 |
Although not yet supported by studies, MDCTA is emerging as a widely used and reliable noninvasive study in this clinical setting. |
MRA |
4 |
Limited data available. Inherent limitations caused by artifact clips. |
INV, angiography (DSA) |
3 |
Indicated if noninvasive studies are abnormal. Not for screening. |
Appropriateness Criteria Scale
1 2 3 4 5 6 7 8 9
1 = Least appropriate 9 = Most appropriate
|
Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.
Lower extremity arterial bypass surgery can be broadly categorized as suprainguinal or infrainguinal, and when infrainguinal as autologous vein, or artificial graft. The postsurgical evaluation previously was limited to clinical observation of recurring symptoms and measurement of ankle-brachial indices (ABI) and segmental volume recordings. Over the past two decades, routine duplex US for asymptomatic patients following infrainguinal bypass has gained much acceptance. Regardless of the category of bypass, symptoms recur or an asymptomatic stenosis is detected, further imaging may be warranted prior to open surgical or endovascular intervention. Conventional (catheter) angiography and, more recently, MRA and CTA may provide needed information regarding the severity and character of stenoses and the quality of the native vessels proximal and distal to the graft. Even in the setting of an acutely threatened limb after bypass graft failure, these studies may be warranted prior to rapid intervention.
The natural history of lower extremity bypass surgery with vein conduit is the development of stenoses within or adjacent to the graft and ultimately thrombosis. Early failures are usually secondary to a technical imperfection such as a retained valve or a kink in the conduit during tunneling. Late failures are usually due to intimal hyperplasia within the graft or at either anastomosis, or progression of atherosclerosis in the inflow or outflow arteries. During the first postoperative year, up to 30% of venous grafts develop stenoses. There is evidence suggesting that repair of these stenoses, by either surgical or endovascular means, extends the patency of venous bypass grafts. In addition, patency following revision of a thrombosed vein graft is inferior to patency following of revision of a stenotic graft prior to thrombosis.
Duplex US has been used as a method of vein graft surveillance for more than 20 years. The technique involves the sequential study of a graft from proximal to distal anastomosis, with measurement of peak systolic flow velocity (PSFV) and comparison of areas of increased velocity to nearby regions of low velocity to create a peak systolic flow velocity ratio (PSFVR). There is evidence to suggest that the PSFVR is the most sensitive indicator of a graft stenosis. A PSFVR of more than 2.5 is often considered representative of a significant stenosis, although there are reports suggesting a higher value of 3.0 or 3.5 as the appropriate threshold for intervention. Another value that may signify a significant stenosis is a PSFV >200 cm/sec at any point in the graft. A midgraft PSFV <45 cm/sec may indicate high resistance, suggesting stenosis in the outflow arteries. However, low PSFV may be seen normally in large caliber vein grafts.
There have been two prospective randomized trials comparing duplex US surveillance versus clinical follow-up of lower extremity bypass grafts with opposite conclusions. One study showed no difference in assisted primary or secondary patency for 185 vein grafts at 1 year. In another study, 165 grafts did show a significant benefit in assisted primary and secondary patency for vein grafts at 3 years, but no benefit in patency for the surveillance of polytetrafluoroethylene (PTFE) grafts. A European randomized control trial of 1,200 patients is pending. A nonrandomized study of 615 bypasses found significant improvement in secondary patency and limb salvage for grafts followed by duplex US and ankle-brachial index compared to clinical surveillance (return of preoperative symptoms).
Arguments against the use of duplex US surveillance include the expense of the machine and the technologist and the lack of a definitive study showing that detectable stenosis will lead to graft failure. However, there is evidence as to the cost effectiveness of such surveillance.
There is strong evidence that using duplex US during the creation of the graft reduces early graft failures. In fact, the most sensitive predictor of subsequent graft stenosis formation was an abnormal duplex US during initial surgery.
Regardless of the indications for re-intervention in a bypass graft, many surgeons obtain arteriography before repair, mainly for evaluating the inflow and outflow vessels. In recent years, MRA, specifically contrast-enhanced MRA, has shown increasing ability to properly evaluate inflow and outflow vessels, as well as bypass grafts. Though less well-studied, CTA with multislice scanner technology has begun to emerge as another alternative to conventional arteriography.
Abbreviations
- CTA, computerized tomography angiography
- DSA, digital subtraction angiography
- MDCTA, multidetector CTA
- MRA, magnetic resonance angiography
- US, ultrasound