A Comparison of Magnetic Resonance Angiography, Contrast Arteriography, and Duplex Arteriography for Patients Undergoing Lower Extremity Revascularization

International Union of Angiology Position Statement on no-option chronic limb threatening ischemia

This position paper, written by members of International Union of Angiology (IUA) Youth Committee and senior experts, shows an overview of therapeutical approaches for patients with chronic limb-threatening ischemia (CLTI) and absence of 'standard' solutions for revascularization. The aim was to demonstrate the accurate management of the 'no-option' CLTI patient including the wound treatment and the rehabilitation, considering always the goal of the increase of quality of life of the patients.

Global Vascular Guidelines on the Management of Chronic Limb-Threatening Ischemia

GUIDELINE SUMMARY

Chronic limb-threatening ischemia (CLTI) is associated with mortality, amputation, and impaired quality of life. These Global Vascular Guidelines (GVG) are focused on definition, evaluation, and management of CLTI with the goals of improving evidence-based care and highlighting critical research needs. The term CLTI is preferred over critical limb ischemia, as the latter implies threshold values of impaired perfusion rather than a continuum. CLTI is a clinical syndrome defined by the presence of peripheral artery disease (PAD) in combination with rest pain, gangrene, or a lower limb ulceration >2 weeks duration. Venous, traumatic, embolic, and nonatherosclerotic etiologies are excluded. All patients with suspected CLTI should be referred urgently to a vascular specialist. Accurately staging the severity of limb threat is fundamental, and the Society for Vascular Surgery Threatened Limb Classification system, based on grading of Wounds, Ischemia, and foot Infection (WIfI) is endorsed. Objective hemodynamic testing, including toe pressures as the preferred measure, is required to assess CLTI. Evidence-based revascularization (EBR) hinges on three independent axes: Patient risk, Limb severity, and ANatomic complexity (PLAN). Average-risk and high-risk patients are defined by estimated procedural and 2-year all-cause mortality. The GVG proposes a new Global Anatomic Staging System (GLASS), which involves defining a preferred target artery path (TAP) and then estimating limb-based patency (LBP), resulting in three stages of complexity for intervention. The optimal revascularization strategy is also influenced by the availability of autogenous vein for open bypass surgery. Recommendations for EBR are based on best available data, pending level 1 evidence from ongoing trials. Vein bypass may be preferred for average-risk patients with advanced limb threat and high complexity disease, while those with less complex anatomy, intermediate severity limb threat, or high patient risk may be favored for endovascular intervention. All patients with CLTI should be afforded best medical therapy including the use of antithrombotic, lipid-lowering, antihypertensive, and glycemic control agents, as well as counseling on smoking cessation, diet, exercise, and preventive foot care. Following EBR, long-term limb surveillance is advised. The effectiveness of nonrevascularization therapies (eg, spinal stimulation, pneumatic compression, prostanoids, and hyperbaric oxygen) has not been established. Regenerative medicine approaches (eg, cell, gene therapies) for CLTI should be restricted to rigorously conducted randomizsed clinical trials. The GVG promotes standardization of study designs and end points for clinical trials in CLTI. The importance of multidisciplinary teams and centers of excellence for amputation prevention is stressed as a key health system initiative.

Global vascular guidelines on the management of chronic limb-threatening ischemia

Chronic limb-threatening ischemia (CLTI) is associated with mortality, amputation, and impaired quality of life. These Global Vascular Guidelines (GVG) are focused on definition, evaluation, and management of CLTI with the goals of improving evidence-based care and highlighting critical research needs. The term CLTI is preferred over critical limb ischemia, as the latter implies threshold values of impaired perfusion rather than a continuum. CLTI is a clinical syndrome defined by the presence of peripheral artery disease (PAD) in combination with rest pain, gangrene, or a lower limb ulceration >2 weeks duration. Venous, traumatic, embolic, and nonatherosclerotic etiologies are excluded. All patients with suspected CLTI should be referred urgently to a vascular specialist. Accurately staging the severity of limb threat is fundamental, and the Society for Vascular Surgery Threatened Limb Classification system, based on grading of Wounds, Ischemia, and foot Infection (WIfI) is endorsed. Objective hemodynamic testing, including toe pressures as the preferred measure, is required to assess CLTI. Evidence-based revascularization (EBR) hinges on three independent axes: Patient risk, Limb severity, and ANatomic complexity (PLAN). Average-risk and high-risk patients are defined by estimated procedural and 2-year all-cause mortality. The GVG proposes a new Global Anatomic Staging System (GLASS), which involves defining a preferred target artery path (TAP) and then estimating limb-based patency (LBP), resulting in three stages of complexity for intervention. The optimal revascularization strategy is also influenced by the availability of autogenous vein for open bypass surgery. Recommendations for EBR are based on best available data, pending level 1 evidence from ongoing trials. Vein bypass may be preferred for average-risk patients with advanced limb threat and high complexity disease, while those with less complex anatomy, intermediate severity limb threat, or high patient risk may be favored for endovascular intervention. All patients with CLTI should be afforded best medical therapy including the use of antithrombotic, lipid-lowering, antihypertensive, and glycemic control agents, as well as counseling on smoking cessation, diet, exercise, and preventive foot care. Following EBR, long-term limb surveillance is advised. The effectiveness of nonrevascularization therapies (eg, spinal stimulation, pneumatic compression, prostanoids, and hyperbaric oxygen) has not been established. Regenerative medicine approaches (eg, cell, gene therapies) for CLTI should be restricted to rigorously conducted randomizsed clinical trials. The GVG promotes standardization of study designs and end points for clinical trials in CLTI. The importance of multidisciplinary teams and centers of excellence for amputation prevention is stressed as a key health system initiative.

Pulse Oximetry as a Screening Test for Hemodynamically Significant Lower Extremity Peripheral Artery Disease in Adults with Type 2 Diabetes Mellitus

Objective

The main objective is to determine if digital pulse oximetry is an acceptable screening tool to detect hemodynamically significant lower extremity peripheral artery disease (PAD) in patients 50 years old and above with type 2 diabetes mellitus (T2DM) seen at the University of Santo Tomas Hospital (USTH).

Methodology

A total of 78 subjects (155 limbs) were included. Using duplex ultrasonography as the reference standard for the presence of hemodynamically significant lower extremity PAD, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were obtained for abnormal percent oxygen saturation (SpO₂) gradients and for ankle-brachial index (ABI).

Results

Of the 155 limbs, 38.7% had hemodynamically significant stenosis. Pulse oximetry had 76.7% sensitivity (95% CI, 65.2% to 88.1%), 85.3% specificity (95% CI, 78.0% to 92.6%), 76.7% PPV (95% CI, 66.5% to 84.4%) and 85.3% NPV (95% CI, 78.4% to 90.2%). ABI had 40.7% sensitivity (95% CI, 30.1% to 51.3%), 88.2% specificity (95% CI, 80.0% to 96.3%), 68.6% PPV (95% CI, 53.6% to 80.4%) and 70.1% NPV (95% CI, 65.1% to 74.5%). Combining both produces 88.1% sensitivity (95% CI, 78.5% to 97.8%), 74.2% specificity (95% CI, 65-83.4%), 68.4 PPV (95% CI, 60.3% to 75.6%) and 90.8% NPV (95% CI, 83.0% to 95.2%).

Conclusion

The results of this study suggest that pulse oximetry has a higher sensitivity than ABI as a screening tool for hemodynamically significant lower extremity PAD in T2DM patients 50 years old and above. Combining these two tests may be done to achieve a higher sensitivity.

Comparison of Computed Tomography Angiography to Contrast Arteriography for Patients Undergoing Evaluation for Lower Extremity Revascularization

In an effort to explore alternatives to contrast arteriography, we compared computed tomography angiography to contrast arteriography for defining anatomic features of patients undergoing lower extremity revascularization. From November 2003 to March 2004, 36 inpatients with chronic lower extremity ischemia underwent contrast arteriography and computed tomography angiography before undergoing lower extremity revascularization procedures. A Siemens 16 slice multiplanar computed tomography device with bolus tracking was used for these exams. The reports of these tests and images were compared prospectively, and the differences in the aorto-iliac segment, femoral-popliteal, and infrapopliteal segments were noted. The vessels were classified as mild disease (<50%), moderate disease (50%-70%), severe (71%-99%), and occluded. The studies and treatment plans based on these data were compared. The mean age was 76 ± 12 years (SD). Indications for the procedures included gangrene (45%), ischemic ulcer (32%), rest pain (19%), and severe claudication (3%); 69% were diabetics. Accuracy of computed tomography angiography in the aorto-iliac, femoral-popliteal, and infrapopliteal segments was 100%, 81%, and 59%, respectively. Thirteen of 18 (72%) of these disagreements resulted in a different procedure than that suggested by computed tomography angiography. A review of the data obtained in this series indicated that computed tomography angiography appears to be unable to obtain adequate information in this highly selected population at our institution.

Evaluation of the vessels of the lower leg before microsurgical fibular transfer. Part II: magnetic resonance angiography for standard preoperative assessment

The peroneal artery is the dominant supply of the osteomyocutaneous fibular flap. It has been shown that there can be anatomical variants that could jeopardise the blood supply to the lower limb during harvest of the flap. To avoid postoperative ischaemia of the lower leg, preoperative evaluation of adequate collateral perfusion is essential. We investigated whether magnetic resonance angiography (MRA) accurately shows anatomical variants and pathological stenoses of the vessels of the lower leg and whether it can replace conventional invasive techniques. Conventional digital subtraction angiography (DSA) was used in a prospective study of 15 patients, and contrast-enhanced MRA postoperatively. Arteries were evaluated by three radiologists for: size of vessel at the trifurcation; hypoplastic or missing vessels; appreciable stenosis or vascular occlusion, or both; atherosclerotic malformations; and overall vascular topography. High resolution MRA enabled a reliable judgement to be made of the vessels of the lower leg. MRA definitively detected hypoplastic vessels, stenoses, occlusion, or atherosclerotic changes of the vessels, and enabled both accurate assessment of the quality of vessels and the preferred site for the harvest of the flap. As it is a low risk procedure, it can be done in the outpatient department with no risk of radiation. It can easily replace conventional DSA.

Clinical study of peroneal artery perforators with computed tomographic angiography: implications for fibular flap harvest

PURPOSE

Previous studies of cutaneous perforators of the peroneal artery have shown great variability, and attest to the significant anatomical variability in this region. Furthermore, the vascular anatomy of the region has been considered unreliable in the prediction of ideal perforator topography. Preoperative imaging has been suggested as a means for improving preoperative awareness, with Doppler ultrasound and eco-colour (duplex) ultrasound as useful tools. Multi-detector row computed tomographic angiography (CTA or angio CT), has emerged as a significant improvement, providing non-invasive operator-independent details of the vascular anatomy. We utilised this tool to perform an in vivo, anatomical study of the peroneal artery perforators, and demonstrating the usefulness of CTA in planning the osteocutaneous free fibula flap.

METHODS

Forty-one consecutive patients (82 limbs) underwent CTA of the lower limb vasculature, with the anatomical details of the peroneal artery cutaneous perforators assessed.

RESULTS

CTA was able to demonstrate the size, course and penetration pattern of all perforators over 0.3 mm in diameter, with measurements for perforators over 0.8 mm diameter recorded for analysis. Of 171 such perforators, accurate identification of the size (mean diameter 1.91 mm), course (59.6% septocutaneous, 29.2% musculocutaneous and 11.1% septomusculocutaneous) and location was achieved.

CONCLUSION

The vascular anatomy of peroneal artery perforators is highly variable, and thus there is a role for preoperative imaging. CTA can demonstrate cases where there is aberrant or non-preferred anatomy, or select the limb of choice for harvest.

Reliability of preoperative duplex scanning in designing a therapeutic strategy for chronic lower limb ischemia

The objective of this study was to compare the treatment plan designed on the basis of preoperative duplex scanning evaluation of the critical limb ischemia with the treatment plan finally carried out, after assessing the findings obtained during surgical or endovascular treatment. Over a period of 51 months a preoperative duplex scanning study was carried out in 335 consecutive patients with chronic critical ischemia, to design the best therapeutic strategy. Agreement between both plans were as follows: 80%, 82,7% and 59% in the examinations of the iliac arteries, femoropopliteal or tibial arteries respectively. The operation plan was more frequently modified due to a duplex scanning failure in procedures involving the the distal vessels(10 of 44 [22.7%], p < 0.01). In conclusion, duplex scanning evaluation of patients with occlusive arterial disease of the lower limbs permits the design of both a medical and a surgical or endovascular treatment plan with a high level of agreement with the findings obtained during the revascularization procedure.

Magnetic resonance angiography: current status in the planning and follow-up of endovascular treatment in lower-limb arterial disease

Magnetic resonance angiography (MRA) has become an established imaging modality in the management of lower-limb arterial disease, with emerging roles in treatment planning and follow-up. Contrast-enhanced MRA is now the most widely used technique with clinically acceptable results in the majority of patients. Difficulties in imaging and image interpretation are recognised in certain subgroups, including patients with critical limb ischaemia as well as patients with stents. Although newer contrast agents and refined imaging protocols may offer some solutions to these problems, this optimism is balanced by concerns about the toxicity of certain gadolinium chelates. Further development of interventional MRA remains one of the most significant challenges in the development of magnetic resonance imaging-guided peripheral vascular intervention. The status of MRA in managing patients with lower-limb arterial disease in current clinical practice is reviewed.

Limitations of and Lessons Learned from Clinical Experience of 1,020 Duplex Arteriography

Objective: Due to the inherent risks, deficiencies and cost associated with contrast arteriography (CA), our group has been utitilizing duplex arteriography (DA) for evaluating the arteries of the lower extremity for patients undergoing lower extremity revascularization. In an effort to further explore the strengths and weaknesses of DA, we reviewed our evolving experience with DA from January 1, 1998, to January 1, 2005.

Patients and Methods: The arterial segments starting from mid-abdominal aorta to the pedal arteries were studied in cross-sectional and longitudinal planes using a variety of scanheads of 7–4, 10–5, 12–5, 5–2 and 3–2 MHz extended operative frequency range to obtain high-quality B-mode, color and power Doppler images as well as velocity spectra. In 906 patients, 1,020 duplex arteriograms were obtained. The ages ranged from 30–98 years old with a mean of 73±11 (SD) years. Fifty percent of the patients were diabetics. Indications for the examination included: tissue loss (409), rest pain (221), claudication (310), acute ischemia (74), popliteal aneurysm (45), SFA aneurysm (2), abdominal aortic aneurysms (AAA) (10) and failing bypass (55). Prior procedures had been performed in 262. DA was performed by six technologists (4 of whom are MDs). In all, 207 DA were performed intraoperatively and the remainder, preoperatively.

Results: The resultant procedures based upon DA included: bypass to the popliteal artery (262) and bypass to an infrapopliteal artery (325), endovascular procedures (363), thrombectomy (11), embolectomy (9), inflow bypass procedures to the femoral arteries (46), débridment (4), amputation (8) and no intervention (75). The areas not visualized well included: iliac (73), femoral (26), popliteal (17), and infrapopliteal (221). Additional imaging after DA was deemed necessary in 102 cases to obtain enough information to plan lower extremity revascularization. Factors associated with increased need to obtain CA included: DM ( p<.001), infrapopliteal calcification ( p<.001), older age ( p = .01) and limb threatening ischemia ( p<.001). Factors not associated with the need to obtain CA included: which technologist performed the exam, whether the technologist has a medical degree and whether the patient underwent prior revascularization.

Conclusions: In 90% of patients reviewed, DA is able to obtain the needed information to plan lower extremity revascularization. Severe tibial vessel calcification is the most common cause of an incomplete DA exam and determines when alternative imaging modalities need to be obtained.

A Prospective Feasibility Study of Duplex Ultrasound Arterial Mapping, Digital-Subtraction Angiography, and Magnetic Resonance Angiography in Management of Critical Lower Limb Ischemia by Endovascular Revascularization

Duplex ultrasound arterial mapping (DUAM) allows precise evaluation of peripheral vascular disease (PVD). However, magnetic resonance angiography (MRA) and digital-subtraction angiography (DSA) are the diagnostic tools used most frequently prior to intervention. Our aim was to compare clinical pragmatism, hemodynamic outcomes, and cost-effectiveness when using DUAM alone compared to DSA or MRA as preoperative assessment tools for endovascular revascularization (EvR) in critical lower limb ischemia (CLI). From 2002 through 2005, 465 patients were referred with PVD. Of these, 199 had CLI and 137 required EvR. Preoperative diagnostic evaluation included DUAM (n = 41), DSA (n = 50), or MRA (n = 46). EvR was aortoiliac in 27% of cases and infrainguinal in 73%. Patients were assessed at day 1, 6 weeks, 3 months, and 6 months. Composite end points were relief of rest pain, ulcer/gangrene healing, and increase in perfusion pressure, as measured by ankle-brachial index (ABI) and digital pressures. Patency by DUAM, limb salvage, morbidity, mortality, length of stay, and cost-effectiveness were compared between groups using nonparametric t-test, analysis of variance, and Kaplan-Meier analysis. The three groups were comparable in terms of age, sex, comorbidity, and Society for Vascular Surgery/International Society of Cardiovascular Surgery clinical classification. Six-month mean improvement in ABI in the DUAM group was comparable to that in the DSA group (P = 0.25) and significantly better than that in the MRA group (P < 0.05). Six-month patency rates for the DUAM group were comparable to those in the DSA group (P = 0.68, relative risk [RR] = 0.74, 95% confidence interval [CI] 0.18-2.99) and superior to that in the MRA group (P = 0.022, RR = 0.255, 95% CI 0.09-0.71). Length of hospital stay was lower in the DUAM group compared with the DSA group (P < 0.0001) and the MRA group (P = 0.0003). The cost of DUAM is lower than that of both DSA and MRA. DUAM accurately identified the total number of target lesions for revascularization; however, MRA overestimated it. Our results indicate that DUAM is outstanding when compared with other available modalities as a preoperative imaging tool in a successful EvR program. DUAM is a minimally invasive preoperative evaluation for EvR and offers precise consecutive data with patency and limb salvage rates comparable to EvR based on DSA and superior to MRA. We believe that our feasibility study has established DUAM as an economically proficient primary modality for investigating patients with CLI that significantly shortens length of hospital stay.

Preprocedural imaging: new options to reduce need for contrast angiography

In vascular surgery, the gold standard for evaluation of the lower-extremity arterial tree has long been contrast arteriography (CA). Associated risks of CA are well-documented and include severe allergic reactions, arterial injury and/or hemorrhage, and contrast-induced nephropathy. Increasingly, less-invasive techniques, with fewer inherent risks for complication, are being explored as diagnostic alternatives. Magnetic resonance angiography, computed tomography angiography, and duplex arteriography, each offer distinct advantages, though are not without limitation. This review explores the indications, advantages, and disadvantages of these newer technologies and provides a comparison to CA as a means for defining the anatomic features of patients undergoing lower-extremity revascularization. This data suggests that noninvasive imaging technologies may, in the future, play an increasingly important role in the surgical evaluation of the patient with lower-extremity ischemia.

Duplex ultrasonography rarely changes management decisions in chronic lower extremity ischemia

The purpose of this study was to determine the proportion of patients presenting with lower extremity pain whose treatment plan was altered by duplex ultrasonography. This prospective study evaluated all patients referred for lower extremity pain who had undergone a lower extremity arterial duplex scan. All patients underwent a history and physical examination by the same vascular surgeon. After the completion of the history and physical examination, the surgeon established a preliminary treatment plan. Subsequently, he reviewed the lower extremity duplex results and established a final treatment plan based on the history, physical examination, and duplex results. Treatment was labeled as either (1) conservative, (2) aggressive, or (3) the patient was considered to have no peripheral vascular disease. The proportion of patients whose primary treatment plan was altered by the addition of duplex ultrasonography was determined. Of 103 patients who entered the study, 7% had no peripheral vascular disease based on the history, physical examination, and duplex scan. Based on the history and physical examination alone, 48.5% were to be treated conservatively and 44.7% aggressively. After reviewing duplex results, the treatment plan was changed in only 5.9% of patients. There was no difference in treatment plan after the addition of the duplex results (p = 0.1025). Duplex ultrasonography remains a valuable tool in the evaluation of patients with lower extremity peripheral vascular disease; however, in most patients, the decision to treat conservatively or aggressively can be made without duplex scanning. All patients referred to the vascular clinic for lower extremity evaluation do not require a duplex scan.

Long-term follow-up of surgically excluded popliteal artery aneurysms with multi-slice CT angiography and Doppler ultrasound

The purpose of this study was to evaluate the role of multi-slice computed tomography (MSCT) angiography in the follow-up of popliteal artery aneurysms (PAAs) that have been operated on. Aneurysm exclusion and progression, graft patency and graft-related complications were analyzed. Fourteen patients with 21 surgically excluded PAAs were evaluated with MSCT angiography with slice thickness of 1.25 mm. The mean follow-up time was 67 months. MSCT demonstrated blood flow in six non-excluded PAAs (24%), with an average increase in the diameter of 21 mm over time. Fifteen PAAs demonstrated no blood flow and revealed an average decrease of 7 mm in diameter. The origin of this residual perfusion was demonstrated, and collaterals were involved in five of six non-excluded PAAs. In addition, MSCT demonstrated three graft stenoses. Furthermore, two occluded grafts were visualized. Twenty-four percent of the patients after surgical exclusion of PAAs revealed residual perfusion within the aneurysmal sac during follow-up, with a significant increase in the aneurysmal size with MSCT. Moreover, evaluation of the graft patency could also be done as could demonstration of anastomotic abnormalities. Thus, MSCT might be considered as a new tool to evaluate residual collateral feeding of popliteal aneurysmal sac and could be useful in identification and localization of feeding vessels.

Computed tomographic angiography allows accurate planning of the setting and technique of open and percutaneous vascular interventions

BACKGROUND

Vascular surgeons can offer patients with arterial and venous disorders a multitude of endovascular and surgical options. Computed tomographic angiography (CTA) has the potential to allow the development of an effective interventional strategy without subjecting patients to invasive diagnostic testing.

METHODS

A prospectively maintained database was reviewed comprising 6 consecutive months of arterial and venous procedures performed using an algorithm emphasizing CTA supplemented with other noninvasive imaging.

RESULTS

Eighty-five patients underwent 90 arterial or venous procedures, the majority of which were based on CTA. Preprocedure plans matched a successful intervention in 35 of 40 (88%) procedures performed in the interventional suite, and 48 of 49 (98%) procedures performed in the surgical suite. Two of 40 patients treated initially in the interventional suite eventually required a surgical vascular procedure. The majority of procedures were therapeutic (86%) rather than diagnostic (14%).

CONCLUSIONS

An algorithm using CTA and supplemented with other noninvasive imaging allows safe and effective planning for open surgical and endovascular procedures.