ACR Appropriateness Criteria®
Clinical Condition: Recurrent Symptoms Following Lower Extremity Angioplasty
Variant 1: Claudication
| Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
| Ankle-brachial indices (ABI) |
9 |
Usual first test. |
| INV, peripheral arteriography |
8 |
Use when it is thought there is likely a lesion amenable to percutaneous intervention (e.g., restenosis). |
| Other physiologic noninvasive tests |
8 |
Used to clarify ABI. |
| US, Duplex Doppler with color |
8 |
Useful screen to define location and extent of lesions. |
| MRA |
8 |
May substitute for other non-invasive studies. |
| CTA, multi-detector |
6 |
Although extensive data are not yet available, experience suggests that this may be or become equivalent to MRA. |
| US, lower extremity, intravascular |
2 |
May be useful in conjunction with angiography to determine the significance of a lesion, but is not indicated alone. |
| US, lower extremity, venous |
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 2: Threatened limb
| Radiologic Exam Procedure |
Appropriateness Rating |
Comments |
| INV, peripheral arteriography |
9 |
Allows diagnosis and treatment. |
| Ankle-brachial indices (ABI) |
8 |
Always useful as a baseline. |
| MRA |
6 |
An adjunct usually useful only if angiography is not to be done (i.e., surgical treatment is necessary). |
| CTA, multi-detector |
6 |
Although extensive data are not yet available, experience suggests that this may be or become equivalent to MRA. |
| Other physiologic noninvasive tests |
4 |
|
| US, Duplex Doppler with color |
4 |
|
| US, lower extremity, intravascular |
2 |
May be useful in conjunction with angiography to determine the significance of a lesion, but is not indicated alone. |
| US, lower extremity, venous |
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.
Endovascular interventions for lower extremity arterial obstructive disease, both for lifestyle-limiting claudication and for critical ischemia with threatened limb, have become accepted treatment modalities. The availability of these techniques has reduced the numbers of surgical reconstructive procedures. But in spite of their very high initial technical success rates, restenosis after angioplasty with recurrent symptoms is frequent, especially with infrainguinal lesions. The use of nitinol stents appears to decrease restenosis in the peripheral arteries. The status of drug-eluting stents in decreasing restenosis is not clear and is still under investigation. The literature has not clarified the importance of the follow-up of patients who have had such interventions. Recurrent symptoms usually precede the onset of limb- or life-threatening events, in contrast to what may occur with coronary artery disease. Close surveillance of these patients, therefore, is often not routine; follow-up has often been driven by recurrence of symptoms. The imaging approach to patients with claudication or with acute limb ischemia after angioplasty is the same.
Clinical examination with evaluation of the peripheral pulses and determination of the ABI is the obvious and accepted first step in evaluating these patients. However, restenosis is not always clinically discernible, since the natural progression of the patient's disease process is often characterized by development of new lesions at different sites. Thus definitive diagnosis is important for therapeutic planning, whether for repeat endovascular intervention, for reconstructive vascular surgery, or for medical management.
Noninvasive Hemodynamic Studies
The ABI is the accepted, most commonly performed noninvasive technique for evaluating peripheral vascular disease. Deterioration from previous levels by 0.15 or more has been accepted as indicative of restenosis. However, this measurement is not specific as to site and is of little value in patients with noncompressible arteries, as often occurs in diabetics and patients with renal insufficiency. Similarly, segmental pulse volume recordings, although more site-specific, are not accurate nor do they provide specific enough information for treatment decision-making in patients with symptomatic recurrent peripheral vascular disease.
Ultrasound Imaging
Duplex Doppler color flow vascular US imaging has achieved widespread usage and acceptance in the evaluation of patients with peripheral vascular obstructive disease. It has the ability to localize the site(s) of involvement and assess the hemodynamic significance of the lesions. A major limitation, however, is that it is operator-dependent, requiring a meticulous and compulsive ultrasonographer (either technologist or physician) for accurate results. In good hands, there is a high, although not perfect, correlation with conventional catheter angiography. US is especially appropriate for infrainguinal arterial disease but can also be helpful in evaluating aortoiliac disease in suitable patients (obesity and bowel gas can significantly degrade the quality of the study). Some authorities recommend duplex Doppler scanning as the best screening imaging tool in the initial evaluation of symptomatic peripheral vascular disease. It is also recommended by most of them for routine surveillance, evaluation, or recurrent symptoms following surgical or percutaneous intervention.
Catheter Angiography
Although MRA, CTA, and US have now generally supplanted catheter angiography (CA), CA is still the "gold standard" for peripheral arterial imaging. Its ability to localize and quantify obstructive lesions accurately is exceeded only by intravascular US imaging. It also may allow physiological evaluation by determining pressure gradients. However, it is an invasive technique that has a small but definite risk in every patient and a variable higher risk in patients with severe widespread vascular disease, diabetes, renal insufficiency, or other contraindications to the use of contrast media. CO2-negative contrast angiography may be of value in certain patients at high risk for receiving iodinated contrast medium. Gadolinium contrast agents are thought to be less nephrotoxic and may be used for CA, but their use is limited by the relatively large volumes needed to complete the study and the high cost of the various available agents. Only qualified angiographers should perform CA.
Computed Tomography Angiography
Multidetector CTA (MDCTA) is rapidly evolving in its ability to image peripheral vascular obstructive disease. It has the advantage of allowing very rapid evaluation of a large portion of the arterial tree (for example, from the level of the diaphragm to the foot vessels), noninvasively and in a matter of minutes. Although it is particularly useful for evaluating a defined vascular segment, it is still somewhat limited in the ability to grade the severity of stenotic lesions accurately. Its resolution, however, is improving dramatically with a significant reduction in examination time. It can be used to study segmented arterial components and is particularly good for evaluating aortoiliac disease, especially with its ability to view the image in coronal and sagittal views in addition to the conventional axial projection. Large calcified plaques currently remain a significant problem in quantifying the degree of stenosis. Although it is relatively noninvasive as compared with CA, it has a similar disadvantage in requiring iodinated contrast medium.
Magnetic Resonance Angiography
MRA has become an accepted method of imaging arterial obstructive disease, particularly with gadolinium-enhanced MRA. This modality has the benefit of being totally noninvasive and without any significant risk. It can image the entire vascular system, including difficult-to-visualize tibial and pedal arteries. With specialized techniques it also may be able to assess hemodynamic significance. MRA is challenging conventional CA, although there is a tendency to overestimate stenoses. On the other hand, when there are total occlusions, MRA more reliably defines reconstituted vessels. Metallic stents, especially stainless steel, cause signal intensity dropout, which can be indistinguishable from an occlusion. This is less of a problem with nitinol stents. MRA is now widely available, and its use, especially in conjunction with duplex vascular US, allows reliable determination of appropriate intervention when symptoms occur after angioplasty. It takes longer to acquire images with MRA than with CTA, and reconstruction and interpretation may be more complex. It is, however, similarly noninvasive and has the advantages of not requiring iodinated contrast agents and not using ionizing radiation.
Radionuclide Imaging
Isotopic arterial blood flow measurement has been described as a technique for evaluating the hemodynamic significance of peripheral vascular disease and for evaluating patients who have had endovascular interventions. However, this method is not widely available and does not have anatomic imaging capabilities.
Summary
A complete vascular physical examination, including measurement of the ABI, is obviously the first step in assessing a patient with recurrent symptoms after an initially successful endovascular intervention. With this knowledge the clinician/angiographer can decide on appropriate imaging studies. Duplex Doppler US is generally the first imaging study, and it is followed by one of the angiographic contrast modalities. If it is clear that reintervention (whether endovascular or surgical) is necessary, and the site of the problem is certain, then proceeding directly to catheter angiography (CA) may be appropriate. Preliminary Duplex Doppler US imaging is usually an appropriate starting point as it may more clearly define the problem, confirming a recurrence at the previously treated site or suggesting progression elsewhere. Duplex Doppler scanning is also currently considerably cheaper than CA, MRA, and CTA.
MRA and MDCTA are increasingly promising and available imaging techniques but have several limitations: 1) lack of available room time because of high demand for other examinations; 2) poor ability to distinguish mild and moderate degrees of restenosis; 3) limitation of field of view, a problem only with older CT and MR equipment, that may prevent visualization of the entire vascular tree from the abdominal aorta to the pedal arches; 4) artifacts caused by calcification and metallic devices such as stents and surgical clips; and 5) poor ability to evaluate the condition of the more "normal" adjacent vessel segments. On the other hand, when equipment and expertise are available, with improved accuracy, comprehensiveness, and reproducibility, it may be appropriate to proceed from the clinical examination directly to MRA or MDCTA. MRA has been shown to be able to image potentially by-passable infrapopliteal and pedal vessels that may not be visualized by CA. MRA and MDCTA may more easily visualize lesions obscured by overlying bone cortex in the calf. In patients who are at risk for renal function deterioration and significant reactions to iodinated contrast medium, MRA may be the procedure of choice and even warrant sending a patient to another institution with MRA capability.
Anticipated Exceptions
Patients presenting with critical recurrent ischemia with motor and sensory deficit occurring shortly after a percutaneous intervention (<7-10 days), and in whom the anatomy is well understood, may proceed directly to surgical revascularization by bypass or thrombectomy.
Abbreviations
- ABI, ankle-brachial indices
- CTA, computed tomography angiography
- INV, invasive
- MRA, magnetic resonance angiography
- US, ultrasound
