Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) and the (hoped for) dawn of evidence-based treatment for advanced limb ischemia

The BEST-CLI trial: a multidisciplinary effort to assess which therapy is best for patients with critical limb ischemia

Critical limb ischemia (CLI) is the most severe form of peripheral arterial disease and is associated with a significant risk of limb loss. It is currently treated with limb revascularization by a variety of specialists. Although both open vascular bypass and endovascular therapy are offered to patients with infrainguinal peripheral arterial disease and CLI, significant disagreement exists as to which therapy works best in candidates for both types of intervention. Persistent clinical equipoise in combination with a paucity of comparative effectiveness data to guide treatment of CLI has led to a multidisciplinary effort to organize the Best Endovascular versus Best Surgical Therapy in patients with CLI (BEST-CLI) trial. The BEST-CLI trial is a pragmatic, multicenter, open label, randomized trial that compares best endovascular therapy with best open surgical treatment in patients eligible for both treatments. This trial is highly innovative in both its design and its collaborative nature. BEST-CLI aims to provide urgently needed clinical guidance for CLI management by using (1) a pragmatic design comparing the effectiveness of established techniques while allowing for the introduction of newer therapies as they become available; (2) a novel primary end point that includes limb amputation rates, repeat intervention, and mortality; (3) a multidisciplinary structure that fosters cooperation among interventional cardiologists, interventional radiologists, vascular surgeons, and vascular medicine specialists; and (4) novel techniques to evaluate the cost-effectiveness and quality-of-life outcomes of the 2 treatment strategies being tested.

[Distal revascularization in diabetic patients with chronic limb ischemia]

Diabetes mellitus is an independent risk factor for peripheral artery disease. Life expectancy is 41 months for diabetic patients with an ischemic ulcer. The characteristics of diabetic arteriopathy make its treatment more difficult than in non-diabetic patients. Few data are available about the surgical treatment of arteriopathy in diabetic patients (including angioplasty or bypass), especially in case of distal arteriopathy. The choice of the procedure depends on multiple factors such as the disease localization, its extent, distal blood flow and vascular disease-related surgical risk. The principal aim of revascularisation is to restore direct flow to the foot in order to ensure wound healing and limb salvage. With percutaneous endoluminal angioplasty, limb salvage can be achieved in more than 80% of patients at 1-3 years. The percutaneous procedure is less invasive than open surgery, there are fewer complications, and morbidity and mortality rates are reduced; moreover, a second procedure remains possible in the future. With bypass surgery, the rate of limb salvage exceeds 80% at five years. Nevertheless, peri-operative mortality reaches 3% and arterial anatomy, patient-related risks factors or venous graft availability may be limitations. New endovascular techniques especially designed for the distal arteries of the lower limbs enable very distal revascularization with morbidity and mortality rates lower than with surgery.

Optimal management of infrainguinal arterial occlusive disease

Peripheral arterial occlusive disease is becoming a major health problem in Western societies as the population continues to age. In addition to risk of limb loss, the complexity of the disease is magnified by its intimate association with medical comorbidity, especially cardiovascular and cerebrovascular disease. Risk factor modification and antiplatelet therapy are essential to improve long-term survival. Surgical intervention is indicated for intermittent claudication when a patient’s quality of life remains unacceptable after a trial of conservative therapy. Open reconstruction and endovascular revascularization are cornerstone for limb salvage in patients with critical limb ischemia. Recent advances in catheter-based technology have made endovascular intervention the preferred treatment approach for infrainguinal disease in many cases. Nevertheless, lower extremity bypass remains an important treatment strategy, especially for reasonable risk patients with a suitable bypass conduit. In this review, we present a summary of current knowledge about peripheral arterial disease followed by a review of current, evidence-based medical and surgical therapy for infrainguinal arterial occlusive disease.

Endovascular techniques in limb salvage: infrapopliteal angioplasty

Critical limb ischemia (CLI) results from inadequate blood flow to supply and sustain the metabolic needs of resting muscle and tissue. Infragenicular atherosclerosis is the most common cause of CLI, and it is more likely to develop when multilevel or diffuse arterial disease coincides with compromised run-off to the foot. Reports of good technical and clinical outcomes have advanced the endovascular treatment options, which have gained a growing acceptance as the primary therapeutic strategy for CLI, especially in patients with significant risk factors for open surgical bypass. In fact, endovascular recanalization of below-the-knee arteries has proven to be feasible and safe, reduce the need for amputation, and improve wound healing. The distribution of various vascular territories or angiosomes in the foot has been recognized, and it appears advantageous to revascularize the artery supplying the territory directly associated with tissue loss. In addition, the targeted application and local delivery of drugs using drug-coated balloons (DCB) during angioplasty has the potential to improve patency rates compared to balloon angioplasty alone.

Perivascular delivery of encapsulated mesenchymal stem cells improves postischemic angiogenesis via paracrine activation of VEGF-A

OBJECTIVE

To test the therapeutic activity of perivascular transplantation of encapsulated human mesenchymal stem cells (MSCs) in an immunocompetent mouse model of limb ischemia.

APPROACH AND RESULTS

CD1 mice underwent unilateral limb ischemia, followed by randomized treatment with vehicle, alginate microbeads (MBs), MB-encapsulated MSCs (MB-MSCs), or MB-MSCs engineered with glucagon-like peptide-1. Treatments were applied directly in the perivascular space around the femoral artery. Laser Doppler and fluorescent microsphere assessment of blood flow showed a marked improvement of perfusion in the MB-MSCs and MB-MSCs engineered with glucagon-like peptide-1 groups, which was associated with increased foot salvage particularly in MB-MSCs engineered with glucagon-like peptide-1-treated mice. Histological analysis revealed increased capillary and arteriole density in limb muscles of the 2 MSC groups. Furthermore, MB-MSCs engineered with glucagon-like peptide-1 and, to a lesser extent, MB-MSC treatment increased functional arterial collaterals alongside the femoral artery occlusion. Analysis of expressional changes in ischemic muscles showed that MB-MSC transplantation activates a proangiogenic signaling pathway centered on vascular endothelial growth factor A. In contrast, intramuscular MB-MSCs caused inflammatory reaction, but no improvement of reparative vascularization. Importantly, nonencapsulated MSCs were ineffective either by intramuscular or perivascular route.

CONCLUSIONS

Perivascular delivery of encapsulated MSCs helps postischemic reperfusion. This novel biological bypass method might be useful in patients not amenable to conventional revascularization approaches.

Jetstream® atherectomy for subacutely or chronically occluded femoro-popliteal prosthetic bypass grafts: a report of three cases

A failed infrainguinal bypass is associated with poor prognosis for the limb in question, particularly if the graft was initially placed for limb salvage. Revascularization of occluded grafts is an important but challenging issue. We present three patients with occluded femoro-popliteal graft in whom the Jetstream(®) system was used successfully to perform thromboatherectomy. The Jetstream(®) system is minimally invasive and avoids use of thrombolytic therapy and its associated costs and complications. The device seems to be highly effective in removing thrombus beyond the acute setting.

Critical appraisal of surgical revascularization for critical limb ischemia

Peripheral artery disease is growing in global prevalence and is estimated to afflict between 8 and 12 million Americans. Its most severe form, critical limb ischemia (CLI), is associated with high rates of limb loss, morbidity, and mortality. Revascularization is the cornerstone of limb preservation in CLI, and has traditionally been accomplished with open surgical bypass. Advances in catheter-based technologies, coupled with their broad dissemination among specialists, have led to major shifts in practice patterns in CLI. There is scant high-quality evidence to guide surgical decision making in this arena, and market forces have exerted profound influences. Despite this, available data suggest that the expected outcomes for both endovascular and open surgery in CLI are strongly dependent on definable patient factors such as anatomic distribution of disease, vein quality, and comorbidities. Optimal patient selection is paramount for maximizing benefit with each technique. This review summarizes some of the existing data and suggests a selective approach to revascularization in CLI, which continues to rely on vein bypass surgery as a primary option in appropriately selected patients.

Current state of diagnosis and management of critical limb ischemia

Critical limb ischemia represents the most severe form of peripheral arterial disease and carries with it severe morbidity and mortality risks. Because of comorbidity risks, early diagnosis and aggressive medical management make up an important part of the treatment paradigm for these individuals. However, in addition to managing these comorbid conditions, the physician caring for these individuals must be able to provide revascularization options that will improve arterial flow to the threatened extremity and assure healing of complicated wounds. Both open surgical and endovascular therapies have proven beneficial in restoring flow to severely ischemic limbs in these patients. Additionally, combinations of the above therapeutic methods have offered more available options for these patients. This article reviews care of patients with critical limb ischemia with critical assessment of options for medical and revascularization options.

Optimal conduit choice in the absence of single-segment great saphenous vein for below-knee popliteal bypass

BACKGROUND

Single-segment great saphenous vein (SSGSV) remains the conduit of choice for femoral to below-knee popliteal (F-BK) surgical revascularization. The purpose of this study was to determine the optimal conduit in patients with inadequate SSGSV.

METHODS

This was a retrospective review of a prospectively maintained vascular registry. Patients underwent F-BK bypass with alternative vein (AV; arm vein, spliced GSV, or composite vein) or prosthetic conduit (PC).

RESULTS

From January 1995 to June 2010, 83 patients had unusable SSGSV for F-BK popliteal reconstruction. Thirty-three patients had an AV conduit and 50 had PC. The AV group was a lower median age than the PC group (69 vs 75 years). The two groups were otherwise similar in comorbid conditions of diabetes mellitus (57.6% vs 58.0%; P > .99), smoking (15.2% vs 32.0%; P = .12), and hemodialysis (3% vs 12%; P = .23). The groups were similar in baseline characteristics such as limb salvage as indication (93.9% vs 86.0%; P = .31), mean runoff score (5.2 vs 4.6; P = .39), and prior ipsilateral bypass attempts (18.2% vs 18.0%; P > .99). The AV and PC groups were also similar in 30-day mortality (6.1% vs 4.0%; P > .99) and wound infection rates (6.1% vs 6.0%; P > .99). PC patients were more likely to be discharged on Coumadin (Bristol-Myers Squibb, Princeton, NJ) than AV patients (62.0% vs 27.3%; P = .002). Seventeen of the 50 PC patients (34%) had a distal anastomotic vein cuff. A log-rank test comparison of 5-year outcomes for the AV and PC groups found no significant difference in primary patency (55.3% ± 9.9% vs 51.9% ± 10.8%; P = .82), assisted primary patency (68.8% ± 9.6% vs 54.0% ± 11.0%; P = .45), secondary patency (68.4% ± 9.6% vs 63.7% ± 10.4% for PC; P = .82), or limb salvage rates (96.2% ± 3.8% vs 81.1% ± 8.1%; P = .19). Multivariable analysis demonstrated no association between conduit type and loss of patency or limb. The factors most predictive of primary patency loss were limb salvage as the indication for surgery (hazard ratio [HR], 4.23; 95% confidence interval [CI], 1.65-10.9; P = .003) and current hemodialysis (HR, 3.51; 95% CI, 1.08-11.4; P = .037). The most predictive factor of limb loss was current hemodialysis (HR, 7.02; 95% CI, 1.13-43.4; P = .036).

CONCLUSIONS

For patients with inadequate SSGSV, PCs, with varying degrees of medical and surgical adjuncts, appear comparable to AV sources in graft patency for below-knee popliteal bypass targets. This observation is tempered by the small cohort sample size of this single-institutional analysis. Critical limb ischemia as the operative indication and current hemodialysis predict impaired patency, and hemodialysis is associated with limb loss.

Assessing intraoperative blood flow in cardiovascular surgery

Off-pump coronary arterial bypass grafting and new surgical apparatus and techniques have decreased the mortality rate associated with this procedure to approximately 1.5%. If we could detect problems in the constructed coronary anastomoses by an alternative imaging system to coronary angiography during surgery, decisions to revise the surgical procedure could be made without hesitation. Meanwhile, the intraoperative direct evaluation of intestinal blood flow during abdominal aortic aneurysmal surgery is required to prevent ischemic colitis, which is a devastating complication. Indocyanine green (ICG) has recently improved ophthalmic angiography and the navigation systems of oncological surgery. The fluorescence illumination of ICG with a near-infrared light is captured on camera. In coronary arterial surgery, the ICG imaging system is also becoming increasingly useful. A new ICG imaging system, the HyperEye Medical System (HEMS), provides a clear view of the blood flow and ischemic area with color visualization. Furthermore, its combination with a quantitative blood flow assessment tool such as transit time flow measurement could improve the accuracy of intraoperative examination. In this review, we evaluate the current strategies of assessing blood flow intraoperatively with an ICG imaging system in cardiovascular surgery.

Results With Viabahn-Assisted Subintimal Recanalization for TASC C and TASC D Superficial Femoral Artery Occlusive Disease

Objectives: Many investigators including TransAtlantic Inter-Society Consensus (TASC) recommend against primary endovascular treatment for severe (TASC C and D) superficial femoral artery (SFA) disease. Vein bypass is preferable but may not be appropriate due to comorbidities or lack of suitable vein. This study reviews our results with Viabahn stent graft-assisted subintimal recanalization (VASIR) for TASC C and D SFA atherosclerosis. Methods: In all, 13 males and 14 females, mean age 72 ± 11 years underwent 28 VASIR for severe (TASC C 8 of 28, TASC D 20 of 28, and 5 of 28 no continuous infrapopliteal runoff artery) SFA disease. Indications were claudication (14 of 28 limbs), ischemic rest pain (6 of 28), and tissue loss (8 of 28). Viabahn stent graft-assisted subintimal recanalization was chosen instead of bypass due to comorbidities or lack of vein. Patients received aspirin and, if not already taking warfarin, they also received clopidogrel. Patients were examined with Ankle-brachial Index (ABI) and duplex scan at 1 month, then every 3 months after VASIR. Results Viabahn stent graft-assisted subintimal recanalization was technically successful in all. Ankle-brachial Index averaged 0.47 ± 0.17 preprocedure, 0.89 ± 0.20 postprocedure, and increased by 0.15 or more in every case. Median follow-up is 20 months. There were 3 perioperative (<30 days) and 7 later failures including revision prior to any thrombosis. One patient required amputation. Four have died, 2 with patent grafts, none from causes related to VASIR, all more than 30 days post-VASIR. Estimated 1-year primary and secondary patency were 70% ± 11% and 73% ± 10%. Failure was not significantly associated with indications, comorbidities, or runoff status. There was a clear distinction between patients with early failure and the rest of the patients. None of the 8 patients with failure in the first 8 months after surgery has a patent graft. However, of 17 grafts primarily patent at 8 months, only 2 have failed (1 thrombosed and 1 required preemptive balloon angioplasty). There was a strong trend toward better patency with 6 and 7 mm diameter compared to 5 mm diameter stent grafts. Furthermore, although warfarin was not prescribed as part of the protocol, no patient taking warfarin before and who resumed warfarin after VASIR (n = 4) suffered failure. Conclusions: Despite significant early failures, we found VASIR to be durable in those who did not have early failure. Viabahn stent graft-assisted subintimal recanalization is an acceptable alternative to vein bypass in selected patients with severe SFA disease. Smaller arterial or stent graft diameter may be associated with poorer results. Warfarin may be valuable to reduce the risk of failure after VASIR.

Autologous bone marrow mononuclear cell therapy is safe and promotes amputation-free survival in patients with critical limb ischemia

OBJECTIVE

The purpose of this Phase I open label nonrandomized trial was to assess the safety and efficacy of autologous bone marrow mononuclear cell (ABMNC) therapy in promoting amputation-free survival (AFS) in patients with critical limb ischemia (CLI).

METHODS

Between September 2005 and March 2009, 29 patients (30 limbs), with a median age of 66 years (range, 23-84 years; 14 male, 15 female) with CLI were enrolled. Twenty-one limbs presented with rest pain (RP), six with RP and ulceration, and three with ulcer only. All patients were not candidates for surgical bypass due to absence of a patent artery below the knee and/or endovascular approaches to improving perfusion was not possible as determined by an independent vascular surgeon. Patients were treated with an average dose of 1.7 ± 0.7 × 10(9) ABMNC injected intramuscularly in the index limb distal to the anterior tibial tuberosity. The primary safety end point was accumulation of serious adverse events, and the primary efficacy end point was AFS at 1 year. Secondary end points at 12 weeks posttreatment were changes in first toe pressure (FTP), toe-brachial index (TBI), ankle-brachial index (ABI), and transcutaneous oxygen measurements (TcPO(2)). Perfusion of the index limb was measured with positron emission tomography-computed tomography (PET-CT) with intra-arterial infusion of H(2)O(15). RP, using a 10-cm visual analogue scale, quality of life using the VascuQuol questionnaire, and ulcer healing were assessed at each follow-up interval. Subpopulations of endothelial progenitor cells were quantified prior to ABMNC administration using immunocytochemistry and fluorescent-activated cell sorting.

RESULTS

There were two serious adverse events; however, there were no procedure-related deaths. Amputation-free survival at 1 year was 86.3%. There was a significant increase in FTP (10.2 ± 6.2 mm Hg; P = .02) and TBI (0.10 ± 0.05;P = .02) and a trend in improvement in ABI (0.08 ± 0.04; P = .73). Perfusion index by PET-CT H(2)O(15) increased by 19.3 ± 3.1, and RP decreased significantly by 2.2 ± 0.6 cm (P = .02). The VascuQol questionnaire demonstrated significant improvement in quality of life, and three of nine ulcers (33%) healed completely. KDR(+) but not CD34(+) or CD133(+) subpopulations of ABMNC were associated with improvement in limb perfusion.

CONCLUSION

This Phase I study has demonstrated safety, and the AFS rates suggest efficacy of ABMNC in promoting limb salvage in "no option" CLI. Based on these results, we plan to test the concept that ABMNCs improve AFS at 1 year in a Phase III randomized, double-blinded, multicenter trial.

Understanding objective performance goals for critical limb ischemia trials

Critical limb ischemia (CLI), the most advanced form of peripheral arterial disease, is associated with a high rate of limb loss and substantial mortality. Revascularization remains the cornerstone of limb salvage in the CLI patient, and surgical bypass is the established standard. Endovascular therapies, such as angioplasty, atherectomy, and stenting offer a less-invasive option, but evidence of efficacy is lacking, and no devices are currently approved specifically for CLI. Design and execution of clinical trials in the CLI population are challenging, in part because of the lack of consensus on cohort definitions and relevant endpoints. Recently, the Society for Vascular Surgery undertook an initiative to define therapeutic benchmarks, objective performance goals (OPGs), for CLI. Using surgical bypass with autogenous vein as the standard for comparison, OPGs were developed for nine safety and efficacy measures that could be utilized in the premarket assessment of new devices in CLI. Data from three large randomized controlled trials of surgical bypass for CLI were analyzed. We defined a major adverse limb event (MALE) as a key endpoint for revascularization therapies in CLI--inclusive of amputation (transtibial or above) or any major vascular reintervention (thrombectomy, thrombolysis, or major surgical procedure [new bypass graft, jump/interposition graft revision]) in the index limb. Freedom from perioperative (30-day) death or any MALE (MALE + POD) was suggested as the primary efficacy endpoint for a single-arm trial design in CLI, with an observed rate of 76.9% for the surgical bypass controls at 1 year. Specific high-risk subgroups were also defined from the surgical dataset--based on clinical (age older than 80 years and tissue loss), arterial anatomy (infrapopliteal disease), and conduit quality (inadequate saphenous vein) characteristics. Risk-adjusted OPG were developed for these subgroups of interest. These OPGs define a new set of benchmarks for assessing the performance of revascularization therapies in CLI, and should facilitate clinical trial design and device development in this arena.

Critical limb ischemia

Critical limb ischemia (CLI), defined as chronic ischemic rest pain, ulcers, or gangrene attributable to objectively proven arterial occlusive disease, is the most advanced form of peripheral arterial disease. Traditionally, open surgical bypass was the only effective treatment strategy for limb revascularization in this patient population. However, during the past decade, the introduction and evolution of endovascular procedures have significantly increased treatment options. In a certain subset of patients for whom either surgical or endovascular revascularization may not be appropriate, primary amputation remains a third treatment option. Definitive high-level evidence on which to base treatment decisions, with an emphasis on clinical and cost effectiveness, is still lacking. Treatment decisions in CLI are individualized, based on life expectancy, functional status, anatomy of the arterial occlusive disease, and surgical risk. For patients with aortoiliac disease, endovascular therapy has become first-line therapy for all but the most severe patterns of occlusion, and aortofemoral bypass surgery is a highly effective and durable treatment for the latter group. For infrainguinal disease, the available data suggest that surgical bypass with vein is the preferred therapy for CLI patients likely to survive 2 years or more, and for those with long segment occlusions or severe infrapopliteal disease who have an acceptable surgical risk. Endovascular therapy may be preferred in patients with reduced life expectancy, those who lack usable vein for bypass or who are at elevated risk for operation, and those with less severe arterial occlusions. Patients with unreconstructable disease, extensive necrosis involving weight-bearing areas, nonambulatory status, or other severe comorbidities may be considered for primary amputation or palliative measures.