Surgical and endovascular venous arterialization for treatment of critical limb ischaemia

Technical Aspects of Percutaneous Deep Venous Arterialization Using Off-the-Shelf Devices

PURPOSE

Chronic limb-threatening ischemia (CLTI) represents the clinical end stage of lower extremity peripheral arterial disease (PAD). Although conventional open and endovascular revascularization options are available, some CLTI patients do not respond to these treatments, generally due to small vessel occlusive disease, with only limited or no clinical improvement achieved. This article aims to provide insights related to pertinent venous anatomy of the leg and below the ankle and a technical review of percutaneous deep venous arterialization (pDVA) creation using commonly-available devices.

TECHNIQUE

For patients with "no-option" CLTI, the risk of major amputation and mortality remains high. Although arterial revascularization remains the optimal treatment of CLTI, some patients with severely-diseased or gracile distal arteries have poor outcome. Deep venous arterialization (DVA), in a subset of patients with tibial anatomy amenable to DVA creation, represents the last-ditch attempt before these patients are deemed to have "no-hope" at limb salvage, and major amputation becomes necessary. Refinement in technique and advancement in device development have been shown to allow pDVA to be created with respectable outcomes for the "no-option" CLTI patient population.

CONCLUSION

The pDVA has garnered increasing interest among endovascular specialists to further understand the anatomical and technical key points of this procedure, and it may yet prove to be a useful addition in the armamentarium in our battle against CLTI.

CLINICAL IMPACT

Percutaneous deep venous arterialisation provides another option in the treatment of challenging "no-option" CLTI patients, and off-the-shelf devices will allow this procedure to be performed in centers where dedicated devices are not available.

Dapagliflozin promotes angiogenesis in hindlimb ischemia mice by inducing M2 macrophage polarization

Critical limb ischemia (CLI) is associated with a higher risk of limb amputation and cardiovascular death. Dapagliflozin has shown great potential in the treatment of cardiovascular disease. However, the effects of dapagliflozin on CLI and the underlying mechanisms have not been fully elucidated. We evaluated the effect of dapagliflozin on recovery from limb ischemia using a mouse model of hindlimb ischemia. The flow of perfusion was evaluated using a laser Doppler system. Tissue response was assessed by analyzing capillary density, arterial density, and the degree of fibrosis in the gastrocnemius muscle. Immunofluorescence and Western blot were used to detect the expression of macrophage polarization markers and inflammatory factors. Our findings demonstrate the significant impact of dapagliflozin on the acceleration of blood flow recovery in a hindlimb ischemia mouse model, concomitant with a notable reduction in limb necrosis. Histological analysis revealed that dapagliflozin administration augmented the expression of key angiogenic markers, specifically CD31 and α-SMA, while concurrently mitigating muscle fibrosis. Furthermore, our investigation unveiled dapagliflozin's ability to induce a phenotypic shift of macrophages from M1 to M2, thereby diminishing the expression of inflammatory factors, including IL-1β, IL-6, and TNF-α. These effects were partially mediated through modulation of the NF-κB signaling pathway. Lastly, we observed that endothelial cell proliferation, migration, and tube-forming function are enhanced in vitro by utilizing a macrophage-conditioned medium derived from dapagliflozin treatment. Taken together, our study provides evidence that dapagliflozin holds potential as an efficacious therapeutic intervention in managing CLI by stimulating angiogenesis, thereby offering a novel option for clinical CLI treatment.

Arterialization of plantar venous system via vein graft: A novel technique for reconstruction of heel pad degloving injuries

BACKGROUND

Patients with heel pad degloving injury frequently develop ischemic necrosis of the area, necessitating soft-tissue reconstruction surgery. We have developed a technique for arterialization of the plantar venous system via vein graft (APV) as the primary revascularization treatment. The objective of this study was to clarify both the utility of APV for the preservation of degloved heel pads and the impact of this preservation on clinical outcomes.

METHODS

Ten consecutive cases of degloving injury with devascularized heel pad were treated at a single trauma center from 2008 to 2018. Five cases underwent APV and five underwent conventional primary suture (PS) as the initial treatment. We evaluated the course according to the frequency of heel pad preservation, additional intervention after heel pad necrosis, post-operative complications, and outcomes using the Foot and Ankle Disability Index score (FADI) at the time of last follow-up.

RESULTS

Among the five cases that underwent APV, the heel pad was preserved in three cases and flap surgery was required in two cases. All cases that underwent PS developed necrosis of the heel pad, requiring skin graft in one case and flap surgery in four. One skin graft case and one free flap case after PS developed plantar ulcers. The three cases with preserved heel pads exhibited higher FADI than the seven cases that developed necrosis.

CONCLUSION

APV showed a relatively high frequency of heel pad preservation, which otherwise was uniformly lacking. Functional outcomes were improved in cases with preserved heel pad compared to those that developed necrosis and underwent additional tissue reconstruction.

Assessment of endothelial colony forming cells delivery routes in a murine model of critical limb threatening ischemia using an optimized cell tracking approach

Background

Endothelial colony forming cells (ECFCs), alone or in combination with mesenchymal stem cells, have been selected as potential therapeutic candidates for critical limb-threatening ischemia (CLTI), mainly for those patients considered as “no-option,” due to their capability to enhance revascularization and perfusion recovery of ischemic tissues. Nevertheless, prior to translating cell therapy to the clinic, biodistribution assays are required by regulatory guidelines to ensure biosafety as well as to discard undesired systemic translocations. Different approaches, from imaging technologies to qPCR-based methods, are currently applied.

Methods

In the current study, we have optimized a cell-tracking assay based on DiR fluorescent cell labeling and near-infrared detection for in vivo and ex vivo assays. Briefly, an improved protocol for DiR staining was set up, by incubation of ECFCs with 6.67 µM DiR and intensive washing steps prior cell administration. The minimal signal detected for the residual DiR, remaining after these washes, was considered as a baseline signal to estimate cell amounts correlated to the DiR intensity values registered in vivo. Besides, several assays were also performed to determine any potential effect of DiR over ECFCs functionality. Furthermore, the optimized protocol was applied in combination with qPCR amplification of specific human Alu sequences to assess the final distribution of ECFCs after intramuscular or intravenous administration to a murine model of CLTI.

Results

The optimized DiR labeling protocol indicated that ECFCs administered intramuscularly remained mainly within the hind limb muscle while cells injected intravenously were found in the spleen, liver and lungs.

Conclusion

Overall, the combination of DiR labeling and qPCR analysis in biodistribution assays constitutes a highly sensitive approach to systemically track cells in vivo. Thereby, human ECFCs administered intramuscularly to CLTI mice remained locally within the ischemic tissues, while intravenously injected cells were found in several organs. Our data corroborate the need to perform biodistribution assays in order to define specific parameters such as the optimal delivery route for ECFCs before their application into the clinic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02943-8.

Eligibility of Patients with Chronic Limb Threatening Ischemia for Deep Venous Arterialization

OBJECTIVES

Percutaneous deep venous arterialization (pDVA) has emerged as a new modality for limb salvage in patients with chronic limb threatening ischemia (CLTI) and no standard option for revascularization. The proportion of patients facing major amputation that are eligible for this technology remains unknown. This study aims to provide a real-life estimate of patient eligibility for pDVA to reduce major amputations.

METHODS

Electronic medical records of 100 consecutive patients with peripheral arterial disease (PAD) who underwent major amputation of 106 limbs were reviewed. Angiograms performed ≤6 months before amputation were assessed by two vascular surgeons. Disease severity was categorized using the Global Limb Anatomic Staging System and patients were classified as ideal, possible, or not candidates for pDVA. Ideal candidates had ≥1 patent tibial artery, no target in the foot, and no proximal disease. Possible candidates had ≥1 patent tibial artery with PAD, no target in the foot, and proximal disease amenable to endovascular therapy. Patients were not eligible if there was no patent tibial artery, extensive PAD, or an arterial target in the foot for bypass.

RESULTS

Of 106 limbs reviewed, 35 (33%) did not undergo angiography ≤6 months before amputation because of infection (n=14), advanced tissue loss (n=10), failed revascularizations (n=8), advanced limb ischemia (n=2), and refusing revascularization (n=1). Thus, 69 lower extremity angiograms (2 incomplete excluded) in 68 patients were analyzed. 15 patients with 16 limbs (23.2%) were identified as candidates for pDVA (ideal=7, possible=9). There were no differences in demographics between the two groups, but candidates for pDVA were less likely to have hyperlipidemia and congestive heart failure than those who were not candidates. pDVA candidates underwent significantly fewer interventions prior to major amputation compared to patients who were not candidates (1.50 ± 0.73 vs 2.61 ± 2.57, p=0.007). Angiographically, patients who were pDVA candidates had significantly higher Inframalleolar GLASS grades (1.81 ± 0.40 vs 0.86 ± 0.41, p<0.0001) but lower Femoropopliteal Glass grades (0.73 ± 1.10 vs 2.43 ± 1.71, p<0.0001) than patients who were not candidates. There was no significant difference in GLASS stage between these two groups (p=0.368). After mean follow-up of 48 months, there was no difference in mortality between both groups (40% vs 32.1%, p=0.567).

CONCLUSION

Among patients considered for revascularization, 23.2% had favorable angiography and 14.7% could have benefited for pDVA as a new therapeutic modality for limb salvage. 33% of major amputations were performed for clinically-deemed unsalvageable CLTI.

Comparison of clinical outcomes, including the wound healing rate, between inframalleolar bypass to the pedal artery and that to the pedal branch artery in the modern endovascular era

OBJECTIVE

Inframalleolar (IM) bypass has been reported to demonstrate acceptable patency and limb salvage in chronic limb-threatening ischemia (CLTI) patients. However, wound healing after IM bypass and comparisons between pedal artery (PA) bypass and pedal branch artery (PBA) bypass are lacking.

METHODS

We reviewed prospectively collected data from 208 consecutive patients after IM bypass performed over a period of six years. Patients were divided into two groups based on the distal anastomotic artery: the PA group (dorsal pedis artery or common plantar artery) and the PBA group (medial tarsal, lateral tarsal, medial plantar, and lateral plantar artery). The primary outcome was wound healing, and secondary outcomes included loss of patency and limb and life prognosis.

RESULTS

Of the 208 patients, 174 (74%) had PA bypass, whereas 34 (16%) had PBA bypass. Patients in the PBA group were significantly younger than those in the PA group (69 ± 7 vs. 73 ± 9, P = .03). Although early (30-day) graft failure was more common in the PBA group, late clinical outcomes, including the wound healing rate (79% in the PA group and 84% in the PBA group, P=.74), were similar between the two groups. The Global Limb Anatomic Staging System (GLASS) IM grade (HR, 0.73; 95% confidence interval [CI], 0.58-0.93: P=.006); wound, ischemia, and foot infection (WIfI) wound grade (HR, 0.67; 95% CI, 0.51-0.89: P<.01); and WIfI foot infection grade (HR, 0.79; 95% CI, 0.65-0.96: P=.02) were independent predictors of wound healing.

CONCLUSIONS

The current study revealed that wound healing in patients following PBA bypass was acceptable and comparable to that following PA bypass. In the modern era, including high prevalence of infrapopliteal angioplasty, our results could provide useful information to clinicians in actual clinical settings. Moreover, PBA bypass may be an alternative revascularization procedure to avoid major amputation when the pedal artery is occluded, such as in the GVG IM P2 grade. Prospective multicenter larger studies are warranted to confirm the findings of this study and to compare PBA bypass and IM EVT in anatomical "no-option" CLTI.

Current Status of Angiogenic Cell Therapy and Related Strategies Applied in Critical Limb Ischemia

Critical limb ischemia (CLI) constitutes the most severe form of peripheral arterial disease (PAD), it is characterized by progressive blockade of arterial vessels, commonly correlated to atherosclerosis. Currently, revascularization strategies (bypass grafting, angioplasty) remain the first option for CLI patients, although less than 45% of them are eligible for surgical intervention mainly due to associated comorbidities. Moreover, patients usually require amputation in the short-term. Angiogenic cell therapy has arisen as a promising alternative for these "no-option" patients, with many studies demonstrating the potential of stem cells to enhance revascularization by promoting vessel formation and blood flow recovery in ischemic tissues. Herein, we provide an overview of studies focused on the use of angiogenic cell therapies in CLI in the last years, from approaches testing different cell types in animal/pre-clinical models of CLI, to the clinical trials currently under evaluation. Furthermore, recent alternatives related to stem cell therapies such as the use of secretomes, exosomes, or even microRNA, will be also described.

REX-001, a BM-MNC Enriched Solution, Induces Revascularization of Ischemic Tissues in a Murine Model of Chronic Limb-Threatening Ischemia

Background: Bone Marrow Mononuclear Cells (BM-MNC) constitute a promising alternative for the treatment of Chronic Limb-Threatening ischemia (CLTI), a disease characterized by extensive blockade of peripheral arteries, clinically presenting as excruciating pain at rest and ischemic ulcers which may lead to gangrene and amputation. BM-MNC implantation has shown to be efficient in promoting angiogenesis and ameliorating ischemic symptoms in CLTI patients. However, the variability seen between clinical trials makes necessary a further understanding of the mechanisms of action of BM-MNC, and moreover, to improve trial characteristics such as endpoints, inclusion/exclusion criteria or drug product compositions, in order to implement their use as stem-cell therapy.

Materials: Herein, the effect of REX-001, a human-BM derived cell suspension enriched for mononuclear cells, granulocytes and CD34+ cells, has been assessed in a murine model of CLTI. In addition, a REX-001 placebo solution containing BM-derived red blood cells (BM-RBCs) was also tested. Thus, 24 h after double ligation of the femoral artery, REX-001 and placebo were administrated intramuscularly to Balb-c nude mice (n:51) and follow-up of ischemic symptoms (blood flow perfusion, motility, ulceration and necrosis) was carried out for 21 days. The number of vessels and vascular diameter sizes were measured within the ischemic tissues to evaluate neovascularization and arteriogenesis. Finally, several cell-tracking assays were performed to evaluate potential biodistribution of these cells.

Results: REX-001 induced a significant recovery of blood flow by increasing vascular density within the ischemic limbs, with no cell translocation to other organs. Moreover, cell tracking assays confirmed a decrease in the number of infused cells after 2 weeks post-injection despite on-going revascularization, suggesting a paracrine mechanism of action.

Conclusion: Overall, our data supported the role of REX-001 product to improve revascularization and ischemic reperfusion in CLTI.

Midterm Outcomes of Percutaneous Deep Venous Arterialization With a Dedicated System for Patients With No-Option Chronic Limb-Threatening Ischemia: The ALPS Multicenter Study

Purpose: To evaluate the midterm results of patients suffering from no-option chronic limb-threatening ischemia (CLTI) treated with a dedicated system for percutaneous deep venous arterialization (pDVA). Materials and Methods: Thirty-two consecutive CLTI patients (mean age 67±14 years; 20 men) treated with pDVA using the Limflow device at 4 centers between 11 July 2014 and 11 June 2018 were retrospectively analyzed. Of all patients, 21 (66%) had diabetes, 8 (25%) were on immunosuppression, 4 (16%) had dialysis-dependent renal failure, 9 (28%) had Rutherford category 6 ischemia, and 25 (78%) were deemed at high risk of amputation. The primary outcome was amputation-free survival (AFS) at 6 months. Secondary outcomes were wound healing, limb salvage, and survival at 6, 12, and 24 months. Results: Technical success was achieved in 31 patients (96.9%). The median follow-up was 34 months (range 16-63). At 6, 12, and 24 months, estimates were 83.9%, 71.0%, and 67.2% for AFS, 86.8%, 79.8% and 79.8% for limb salvage, and 36.6%, 68.2%, and 72.7% for complete wound healing, respectively. Median time to complete wound healing was 4.9 months (range 0.5-15). The DVA circuit occluded during follow-up in 21 patients; the median time to occlusion was 2.6 months. Reintervention for occlusion was performed in 17 patients: 16 because of unhealed wounds and 1 for a newly developed ulcer. Conclusion: This study represents the largest population of patients with no-option CLTI treated with pDVA using the LimFlow device with midterm results. In this complex group of patients, pDVA using the LimFlow device has been shown to be feasible, with a high technical success rate and AFS at 6 up to 24 months coupled with wound healing. In selected patients with no-option CLTI, pDVA could be a recommended treatment to prevent amputation and heal wounds.

Lymphaticovenular anastomosis and venous arterialization in coexisting Raynaud's phenomenon and lymphedema: A case report

Raynaud's phenomenon is highly prevalent in the general population. The optimal medical management for patients with severe Raynaud's phenomenon remains unclear. Venous arterialization (VA) may be considered as a salvage procedure when no distal vessels are available for vascular reconstruction. Surgical treatments for lymphedema, including lymphovenous anastomosis (LVA), are becoming popular alternatives to conservative therapy. Here, we report on a patient with comorbid primary Raynaud's phenomenon and lymphedema in whom both VA and LVA were performed. The patient was a 60-year-old woman with an edematous right upper limb and pain and cold sensitivity in the middle, ring, and small fingers that was refractory to medication. Indocyanine green lymphography and computed tomography angiography suggested coexistence of lymphedema and primary Raynaud's phenomenon. VA and LVA were performed to reduce the risks of cellulitis and amputation. Computed tomography angiography was performed regularly after surgery to examine the arterialized venous system and Doppler echography to search for developing branches. Five months later, three branches of the arterialized veins that flowed proximally at the level of the hand and wrist were ligated. By around 1 year after surgery, the lymphedema index in the affected upper limb had improved from 116 to 103 and the patient's numerical rating scale score for intractable pain and cold sensitivity had improved from 6-7 to 1-2. We believe that the combination of VA and LVA in the early stages of primary Raynaud's phenomenon and lymphedema was effective in this case.

Hybrid Foot Vein Arterialization in No-Option Patients With Critical Limb Ischemia: A Preliminary Report

PURPOSE

To describe a preliminary experience in treating no-option critical limb ischemia (CLI) patients with a hybrid foot vein arterialization (HFVA) technique combining open plus endovascular approaches.

MATERIALS AND METHODS

Between May 2016 and January 2018, 35 consecutive patients (mean age 68±12 years; 28 men) with 36 no-option CLI limbs underwent HFVA in our center. All limbs had grade 3 WIfI (Wound, Ischemia, and foot Infection) ischemia, and the wound classification was grade 1 in 4 (11%) limbs, grade 2 in 4 (11%), and grade 3 in 28 (78%). Surgical bypass was done on the medial marginal vein or a posterior tibial vein, followed by endovascular removal of foot vein valves and embolization of foot vein collaterals. A "tension-free" surgical approach was used to treat foot lesions.

RESULTS

At a mean follow-up of 10.8±2 months, limb salvage was achieved in 25 (69%) limbs and wound healing in 16 (44%); 9 patients presented an unhealed wound. Eleven (31%) patients underwent a major amputation (2 below the knee and 9 thigh). One patient with an unhealed wound and open bypass died of myocardial infarction.

CONCLUSION

HFVA is a promising technique able to achieve acceptable rates of limb salvage and wound healing in no-option patients generally considered candidates for an impending major amputation. Further studies are needed to standardize the technique and better identify patients who can benefit from this approach.

Percutaneous Deep Venous Arterialization for Severe Critical Limb Ischemia in Patients With No Option of Revascularization: Early Experience From Two European Centers

PURPOSE

To report our initial experience of fully percutaneous deep venous arterialization (pDVA) for the treatment of chronic critical limb ischemia (cCLI) after failed distal angioplasty.

MATERIALS AND METHODS

pDVA was performed in five consecutive patients by creating an arteriovenous fistula (AVF) between a below the knee artery and its satellite deep vein. In this early experience, only patients with failed prior interventional attempts at establishing flow with no distal targets for an arterial bypass were selected. Early technical success was defined as successful AVF creation and retrograde venous perfusion of the wound site. Patient demographics, procedural details, morbidity/mortality and wound healing outcomes were assessed prospectively. Patients were followed up in wound care centers, and graft patency was documented on duplex ultrasound.

RESULTS

All five consecutive patients (mean age 58 years) underwent successful pDVA without any procedural complications. There were neither 30-day major adverse limb events nor major cardiovascular complications. Three out of the five patients (60%) had clinical improvement as observed by resolution of rest pain and complete wound healing. At the 1-month FU, one patient died and one patient received a major amputation. The median wound healing time was 39 weeks.

CONCLUSION

pDVA is a safe and feasible vascularization alternative in patients with end-stage/no-option CLI. The early experience highlights the need for a multidisciplinary approach including a dedicated wound care service.