Critical Limb Ischemia: Current Trends and Future Directions

Intentional coronary revascularization versus conservative therapy in patients after peripheral artery revascularization due to critical limb ischemia: the INCORPORATE trial

OBJECTIVES

INCORPORATE trial was designed to evaluate whether default coronary-angiography (CA) and ischemia-targeted revascularization is superior compared to a conservative approach for patients with treated critical limb ischemia (CLI). Registered at clinicaltrials.gov (NCT03712644) on October 19, 2018.

BACKGROUND

Severe peripheral artery disease is associated with increased cardiovascular risk and poor outcomes.

METHODS

INCORPORATE was an open-label, prospective 1:1 randomized multicentric trial that recruited patients who had undergone successful CLI treatment. Patients were randomized to either a conservative or invasive approach regarding potential coronary artery disease (CAD). The conservative group received optimal medical therapy alone, while the invasive group had routine CA and fractional flow reserve-guided revascularization. The primary endpoint was myocardial infarction (MI) and 12-month mortality.

RESULTS

Due to COVID-19 pandemic burdens, recruitment was halted prematurely. One hundred eighty-five patients were enrolled. Baseline cardiac symptoms were scarce with 92% being asymptomatic. Eighty-nine patients were randomized to the invasive approach of whom 73 underwent CA. Thirty-four percent had functional single-vessel disease, 26% had functional multi-vessel disease, and 90% achieved complete revascularization. Conservative and invasive groups had similar incidences of death and MI at 1 year (11% vs 10%; hazard ratio 1.21 [0.49-2.98]). Major adverse cardiac and cerebrovascular events (MACCE) trended for hazard in the Conservative group (20 vs 10%; hazard ratio 1.94 [0.90-4.19]). In the per-protocol analysis, the primary endpoint remained insignificantly different (11% vs 7%; hazard ratio 2.01 [0.72-5.57]), but the conservative approach had a higher MACCE risk (20% vs 7%; hazard ratio 2.88 [1.24-6.68]).

CONCLUSION

This trial found no significant difference in the primary endpoint but observed a trend of higher MACCE in the conservative arm.

A subpopulation of tissue remodeling monocytes stimulates revascularization of the ischemic limb

Despite decades of effort aimed at developing clinically effective cell therapies, including mixed population mononuclear cells, to revascularize the ischemic limb, there remains a paucity of patient-based studies that inform the function and fate of candidate cell types. In this study, we showed that circulating proangiogenic/arteriogenic monocytes (PAMs) expressing the FcγIIIA receptor CD16 were elevated in patients with chronic limb-threatening ischemia (CLTI), and these amounts decreased after revascularization. Unlike CD16-negative monocytes, PAMs showed large vessel remodeling properties in vitro when cultured with endothelial cells and smooth muscle cells and promoted salvage of the ischemic limb in vivo in a mouse model of hindlimb ischemia. PAMs showed a propensity to migrate toward and bind to ischemic muscle and to secrete angiogenic/arteriogenic factors, vascular endothelial growth factor A (VEGF-A) and heparin-binding epidermal growth factor. We instigated a first-in-human single-arm cohort study in which autologous PAMs were injected into the ischemic limbs of five patients with CLTI. Greater than 25% of injected cells were retained in the leg for at least 72 hours, of which greater than 80% were viable, with evidence of enhanced large vessel remodeling in the injected muscle area. In summary, we identified up-regulation of a circulatory PAM subpopulation as an endogenous response to limb ischemia in CLTI and tested a potentially clinically relevant therapeutic strategy.

The antidiabetic drug ipragliflozin induces vasorelaxation of rabbit femoral artery by activating a Kv channel, the SERCA pump, and the PKA signaling pathway

We explored the vasorelaxant effects of ipragliflozin, a sodium-glucose cotransporter-2 inhibitor, on rabbit femoral arterial rings. Ipragliflozin relaxed phenylephrine-induced pre-contracted rings in a dose-dependent manner. Pre-treatment with the ATP-sensitive K+ channel inhibitor glibenclamide (10 μM), the inwardly rectifying K+ channel inhibitor Ba2+ (50 μM), or the Ca2+-sensitive K+ channel inhibitor paxilline (10 μM) did not influence the vasorelaxant effect. However, the voltage-dependent K+ (Kv) channel inhibitor 4-aminopyridine (3 mM) reduced the vasorelaxant effect. Specifically, the vasorelaxant response to ipragliflozin was significantly attenuated by pretreatment with the Kv7.X channel inhibitors linopirdine (10 μM) and XE991 (10 μM), the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin (1 μM) and cyclopiazonic acid (10 μM), and the cAMP/protein kinase A (PKA)-associated signaling pathway inhibitors SQ22536 (50 μM) and KT5720 (1 μM). Neither the cGMP/protein kinase G (PKG)-associated signaling pathway nor the endothelium was involved in ipragliflozin-induced vasorelaxation. We conclude that ipragliflozin induced vasorelaxation of rabbit femoral arteries by activating Kv channels (principally the Kv7.X channel), the SERCA pump, and the cAMP/PKA-associated signaling pathway independent of other K+ (ATP-sensitive K+, inwardly rectifying K+, and Ca2+-sensitive K+) channels, cGMP/PKG-associated signaling, and the endothelium.

Contraindications to use of neuraxial anesthesia for lower limb revascularization surgery in adults: a cross-sectional study

PURPOSE

Nonrandomized and some randomized data suggest neuraxial anesthesia may improve outcomes after lower limb revascularization surgery. Nevertheless, the prevalence of contraindications to neuraxial anesthesia in vascular surgery patients is unknown. We aimed to identify the prevalence of patients with contraindications to neuraxial anesthesia, and to derive and validate a case ascertainment algorithm identifying individuals likely to have contraindications.

METHODS

We conducted a historical cross-sectional study of open lower limb revascularization surgeries performed between 2019 and 2021 at The Ottawa Hospital. Medical records were reviewed for demographic data, admission, procedural characteristics, and presence of contraindications to neuraxial anesthesia. Case ascertainment algorithms to predict the presence of absolute contraindications to neuraxial anesthesia were derived and internally validated.

RESULTS

We identified 340 cases. General anesthesia was used in 219 (64.4%) cases, isolated neuraxial (spinal and/or epidural) in 106 (31.2%) cases, and general plus neuraxial in 15 (4.4%) cases. Seventy-eight (22.9%; 95% confidence interval [CI], 18.8 to 27.7) patients had absolute contraindications to neuraxial anesthesia, primarily because of anticoagulation or antiplatelet medication (89.4%); 21 (6.2%; 95% CI, 4.1 to 9.3) had relative contraindications, primarily long anticipated duration of surgery (16/21, 76.2%). We derived and validated three nested case-ascertainment algorithms. Using admission and procedure variables, discrimination was moderate with moderately explained variance, and calibration was inadequate for reliable use. Patient comorbidity and laboratory data did not improve algorithm performance.

CONCLUSION

Most patients undergoing lower limb revascularization surgery did not have absolute contraindications to neuraxial anesthesia. When present, contraindications typically related to anticoagulation. Admission, procedure, comorbidity, and laboratory data did not provide adequate accuracy to ascertain contraindication status.

The Double Burden: Deciphering Chronic Limb-Threatening Ischemia in End-Stage Renal Disease

BACKGROUND

Chronic limb-threatening ischemia (CLTI) in patients with end-stage renal disease (ESRD) poses significant challenges in clinical management due to its unique pathology and poor treatment outcomes. This review calls for a tailored classification and risk assessment for these patients to guide better revascularization choices with early minor amputation as a first-line strategy in advanced stages.

METHODS

This review consolidates key findings from recent literature on CLTI in ESRD, focusing on disease mechanisms, treatment options, and patient outcomes. It evaluates the literature to clarify the decision-making process for managing CLTI in ESRD.

RESULTS

CLTI in ESRD patients often results in worse clinical outcomes, such as nonhealing wounds, increased limb loss, and higher mortality rates. While the literature reveals ongoing debates regarding the optimal revascularization method, recent retrospective studies and meta-analyses suggest potential benefits of endovascular treatment (EVT) over open bypass surgery (OB) in reducing mortality and wound complications, with comparable amputation-free survival rates.

CONCLUSIONS

The selection of revascularization methods in ESRD patients with CLTI is complex, necessitating individualized strategies. The importance of early detection and timely intervention is critical to decelerate disease progression and improve revascularization outcomes. There is a shift in these treatment strategies toward less invasive endovascular procedures, acknowledging the limitations these patients face with open revascularization surgeries. Considering early minor amputations after revascularization could prevent worse consequences, reflecting a shift in the approach to managing CLTI in ESRD patients.

The impact of ischemic vascular stenosis on LIPU hyperthermia efficacy investigated Based on in vivo rabbit limb ischemia model

Ischemic diseases due to arterial stenosis or occlusion are common and can have serious consequences if untreated. Therapeutic ultrasound like high-intensity focused ultrasound (HIFU) ablates tissues while low-intensity pulsed ultrasound (LIPU) promotes healing at relatively low temperatures. However, blood vessel cooling effect and reduced flow in ischemia impact temperature distribution and ultrasonic treatment efficacy. This work established a rabbit limb ischemia model by ligating the femoral artery, measuring vascular changes and temperature rise during LIPU exposures. Results showed the artery diameter was narrowed by 46.2% and the downstream velocity was reduced by 51.3% after ligation. Finite element simulations verified that the reduced flow velocity impaired heat dissipation, enhancing LIPU-induced heating. Simulation results also suggested the temperature rise was almost related linearly to vessel diameter but decayed exponentially with the increasing flow velocity. Findings indicate that the proposed model could be used as an effectively tool to model the heating effects in ischemic tissues during LIPU treatment. This research on relating varied ischemic flow to LIPU-induced thermal effects is significant for developing safe and efficacious clinical ultrasound hyperthermia treatment protocols for the patients with ischemic diseases.

Transplantation of Human Embryonic Stem Cell-Derived Pericyte-Like Cells Transduced with Basic Fibroblast Growth Factor Promotes Angiogenic Recovery in Mice with Severe Chronic Hindlimb Ischemia

Critical limb ischemia (CLI) is a state of severe peripheral artery disease, with no effective treatment. Cell therapy has been investigated as a therapeutic tool for CLI, and pericytes are promising therapeutic candidates based on their angiogenic properties. We firstly generated highly proliferative and immunosuppressive pericyte-like cells from embryonic stem (ES) cells. In order to enhance the angiogenic potential, we transduced the basic fibroblast growth factor (bFGF) gene into the pericyte-like cells and found a significant enhancement of angiogenesis in a Matrigel plug assay. Furthermore, we evaluated the bFGF-expressing pericyte-like cells in the previously established chronic hindlimb ischemia model in which bone marrow-derived MSCs were not effective. As a result, bFGF-expressing pericyte-like cells significantly improved blood flow in both laser Doppler perfusion imaging (LDPI) and dynamic contrast-enhanced MRI (DCE-MRI). These findings suggest that bFGF-expressing pericyte-like cells differentiated from ES cells may be a therapeutic candidate for CLI.

The comparison of adipose-derived stromal cells (ADSCs) delivery method in a murine model of hindlimb ischemia

BACKGROUND

Adipose-derived stromal cells (ADSCs) demonstrate ability to promote tissue healing and down-regulate excessive inflammation. ADSCs have been used to treat critical limb ischemia in preclinical and clinical trials, but still, there is little known about their optimal delivery strategy. To date, no direct analysis of different methods of ADSCs delivery has been performed in the hindlimb ischemia model. Therefore, in this study we focused on the therapeutic efficacy of different ADSCs delivery methods in a murine model of hindlimb ischemia.

METHODS

For the hADSCs isolation, we used the subcutaneous adipose tissue collected during the surgery. The murine hindlimb ischemia was used as a model. The unilateral femoral artery ligation was performed on 10-12-week-old male C57BL/6. ADSCs were delivered directly into ischemic muscle, into the contralateral muscle or intravenously. 7 and 14 days after the surgery, the gastrocnemius and quadriceps muscles were collected for the immunohistochemical analysis. The results were analyzed with relevant tests using the Statistica software.

RESULTS

Our research revealed that muscle regeneration, angiogenesis, arteriogenesis and macrophage infiltration in murine model of hindlimb ischemia differ depending on ADSCs delivery method. We have demonstrated that intramuscular method (directly into ischemic limb) of ADSCs delivery is more efficient in functional recovery after critical limb ischemia than intravenous or contralateral route.

CONCLUSIONS

We have noticed that injection of ADSCs directly into ischemic limb is the optimal delivery strategy because it increases: (1) muscle fiber regeneration, (2) the number of capillaries and (3) the influx of macrophages F4/80+/CD206+.

Contemporary outcomes of initial treatment strategy of endovascular intervention or bypass in patients with critical limb ischemia

OBJECTIVE

The optimal management for revascularization after critical limb ischemia (CLI) is controversial due to limited studies comparing long-term results of endovascular and open techniques. This study compares long-term outcomes after initial management of CLI via lower extremity bypass (LEB) and percutaneous vascular intervention (PVI).

METHODS

This retrospective cohort study investigates outcomes of patients who underwent endovascular or open surgical management for CLI at a single institution from 2013-2018. All patients with diagnosis of CLI were included and separated based on initial therapy of PVI or LEB. Demographic, procedural, and follow-up data were assessed. Primary endpoints included major adverse limb events (MALE), specifically the need for major amputation and reintervention. Secondary endpoints included mortality at 30 days and one year. A multivariable Cox Proportional Hazard regression model was used to assess the relationship between Surgery group and time to MALE/death while controlling for confounding variables.

RESULTS

This study identified 338 patients with an initial diagnosis of CLI who underwent either LEB (n = 108, 32%) or PVI (n = 230, 68%). The average age was 71.4, 54.4% were male, 30% were African American, 53.6% were diabetic, and 93.2% had hypertension. Patients who underwent LEB were more predominantly smokers (p = .003) and less predominantly on dialysis at time of surgery (p = .01). Re-intervention rates in the bypass group (11%) were not significantly different than the PVI group (9%; p = .95). In the bypass group, 20 (19%) patients had a major amputation with a median time of 189.5 days compared to 23 (10%) patients at a median time of 113 days in the PVI group; however, this difference was not significant (p = .16). There was no significant difference in 1-year mortality between the LEB (2%) and PVI group (4%; p = .2). The cumulative incidence of MALE/death at 30 days was 4.0% in the bypass group and 3.7% in the PVI group (p = .2). Incidences of MALE/death were 21.1% and 48.5% in the bypass group and 19.7 and 45.9% in the PVI group at one and 2 years, respectively. Intervention type was not found to be significantly associated with MALE/death after controlling for possible confounders (HR = 0.82, p = .43).

CONCLUSIONS

In the initial management of CLI, there is no significant difference in long-term outcomes in terms of major amputation, need for reintervention, limb-salvage, and 1-year mortality.

Comparation of drug-eluting stents and control therapy for the treatment of infrapopliteal artery disease: a Bayesian analysis

BACKGROUND

Critical limb-threatening ischaemia is a life-threatening disease which often combines with infrapopliteal arterial disease. Percutaneous transluminal angioplasty (PTA) is recommended as the first-line treatment for infrapopliteal arterial disease. Drug-eluting stent (DES) is another widely used option; however, its long-term therapeutic effect is controversial. The effectiveness of different DES for infrapopliteal arterial disease needs further exploration.

METHODS AND RESULTS

The PubMed, EMBASE, Cochrane Library and Clinical trials were systematically searched from inception to 1 February 2023. Literatures were included if the study was original, peer-reviewed, published in English or Chinese, and contained patients diagnosed with simple infrapopliteal arterial disease or with properly treated combined inflow tract lesions before or during the study procedure. A total of 953 patients, 504 in the DES group and 449 in the PTA/bare-metal stenting (BMS) group, from 12 randomised controlled trials were included in the meta-analysis. The results showed that DES is superior to control group for improving clinical patency, reducing the restenosis rate, and reducing the amputation rate at 6 months, 1 year, and 3 years post-treatment [at 3 years, risk ratio (RR): 1.90, 95% CI 1.23-2.93; RR: 0.87, 95% CI 0.79-0.96; RR: 0.60, 95% CI 0.36-1.00, P =0.049]. In addition, subgroup analyses suggested that DES is superior to BMS and PTA in improving clinical patency and reducing target lesion revascularisation and restenosis rates at 6-month and 1-year post-treatment. The network meta-analysis indicated that sirolimus-eluting stent was superior for improving clinical patency (at 1 year, RR: 0.23, 95% CI 0.08-0.60) and reducing the restenosis rate (at 6 months, RR: 31.58, 95% CI 4.41-307.53, at 1 year, RR: 3.80, 95% CI 1.84-8.87) significantly. However, according to the cumulative rank probabilities test, everolimus-eluting stent may have the lowest target lesion revascularisation rates and amputation rates at 1-year post-treatment (the cumulative rank probability was 77% and 49%, respectively).

CONCLUSIONS

This systematic review and network meta-analysis showed that DES was associated with more clinical efficacy than PTA/BMS significantly. In addition, sirolimus-eluting stent and everolimus-eluting stent may have better clinical benefits.

Implications of Kidney Disease in Patients with Peripheral Arterial Disease and Vascular Calcification

Persons with chronic kidney disease (CKD) are at a higher risk of developing peripheral artery disease (PAD) and its adverse health outcomes than individuals with normal renal function. Among patients with CKD, PAD is predominantly characterized by the calcification of the medial layer of arterial vessels in addition to intimal atherosclerosis and calcification. Vascular calcification (VC) is initiated by CKD-associated hyperphosphatemia, hypercalcemia, high concentrations of parathyroid hormone (PTH) as well as inflammation and oxidative stress. VC is widely prevalent in this cohort (>80% dialysis and 50% patients with CKD) and contributes to reduced arterial compliance and symptomatic peripheral arterial disease (PAD). The most severe form of PAD is critical limb ischemia (CLI) which has a substantial risk for increased morbidity and mortality. Percutaneous endovascular interventions with transluminal angioplasty, atherectomy, and intravascular lithotripsy are the current nonsurgical treatments for severe calcific plaque. Unfortunately, there are no randomized controlled trials that address the optimal approach to PAD and CLI revascularization in patients with CKD.

Vascular regeneration and skeletal muscle repair induced by long-term exposure to SDF-1α derived from engineered mesenchymal stem cells after hindlimb ischemia

Despite recent progress in medical and endovascular therapy, the prognosis for patients with critical limb ischemia (CLI) remains poor. In response, various stem cells and growth factors have been assessed for use in therapeutic neovascularization and limb salvage in CLI patients. However, the clinical outcomes of cell-based therapeutic angiogenesis have not provided the promised benefits, reinforcing the need for novel cell-based therapeutic angiogenic strategies to cure untreatable CLI. In the present study, we investigated genetically engineered mesenchymal stem cells (MSCs) derived from human bone marrow that continuously secrete stromal-derived factor-1α (SDF1α-eMSCs) and demonstrated that intramuscular injection of SDF1α-eMSCs can provide long-term paracrine effects in limb ischemia and effectively contribute to vascular regeneration as well as skeletal muscle repair through increased phosphorylation of ERK and Akt within the SDF1α/CXCR4 axis. These results provide compelling evidence that genetically engineered MSCs with SDF-1α can be an effective strategy for successful limb salvage in limb ischemia.

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.

Expression level and clinical significance of LncRNA PVT1 in the serum of patients with LEASO

Objective

Our study aims to investigate the long non-coding RNA plasmacytoma variant translocation 1 (lncRNA PVT1) in lower extremity arteriosclerosis obliterans (LEASO) patient serum and its clinical significance in LEASO.

Patients and Methods

From July 2021 to April 2022, 133 LEASO patients diagnosed at the Qingdao Municipal Hospital were included. Among them, 44 complicated with coronary artery disease (CAD) were classified as the LEASO with CAD group. The remaining 89 were marked as the LEASO group, which was classified into single (n = 48) and double (n = 41) lower limb groups, with the former being subclassified into the left (n = 28) and right (n = 20) lower limb groups based on the affected sites. Fifty healthy individuals who came to our hospital for physical examination during the same period were randomly included and defined as the Healthy Control group. PVT1 expression was detected in serum samples from each group using a quantitative reverse transcriptase-polymerase chain reaction , and differences in expression levels were calculated. The ankle-brachial index (ABI) of patients in the LEASO group was measured using a sphygmomanometer, and its correlation with PVT1 was analyzed. Clinical data and laboratory test results (including blood routine, liver and renal function, and blood lipids) were collected for all patients upon admission. Logistic regression analyses were performed to determine the influence of PVT1 and laboratory test results on LEASO. The diagnosis and prediction of LEASO were obtained by combing PVT1 with laboratory test indicators.

Results

It was found that lncRNA PVT1 expression was the highest in the serum of the LEASO with CAD group, followed by the LEASO and control groups (P < 0.05). Within the LEASO group, no significant difference in PVT1 expression was seen between the left and right limbs (P > 0.05), nor between the single and double lower limb groups. Furthermore, the PVT1 expression increased with the Rutherford grades, indicating a negative correlation between PVT1 and ABI. Logistic regression analysis revealed that triglycerides (OR = 2.972, 95% CI [1.159-7.618]), cholesterol (OR = 6.655, 95% CI [1.490-29.723]), C-reactive protein (OR = 1.686, 95% CI [1.218-2.335]), and PVT1 (OR = 2.885, 95% CI [1.350-6.167]) were independent risk factors for LEASO. Finally, strong sensitivity was observed in the receiver operating characteristic curve when combining PVT1 with meaningful laboratory indicators to diagnose and predict LEASO.

Conclusion

lncRNA PVT1 promotes LEASO occurrence and progression and is related to atherosclerosis severity. The expression of PVT1 was negatively correlated with ABI. Logistic regression analysis suggested that blood lipid levels and inflammatory reactions might be related to LEASO occurrence. PVT1 was incorporated into laboratory indicators to predict LEASO. The subject's working curve area was large, and the prediction results were highly sensitive.

Updates and Advances in Cardiovascular Nursing: Peripheral Arterial Disease

This article focuses on peripheral arterial disease (PAD) of the lower extremities. There is a higher incidence of myocardial infarction, stroke, and cardiovascular death, resulting in higher rates of all-cause mortality compared with patients without PAD. Thus, the presence of PAD is a marker for systemic atherosclerotic disease and can lead to the early detection and treatment of coronary artery disease or cerebrovascular disease. This article reviews the latest information about the prevalence, symptoms, classification, diagnosis, and treatment of PAD. Monitoring and detection of PAD are also discussed, including implications for nursing care.

Examination of Lower Limb Microcirculation in Diabetic Patients with and without Intermittent Claudication

Intermittent claudication is a frequent complaint in lower extremity artery disease, but approximately two thirds of patients are asymptomatic, most of which are diabetic patients. Non-invasive angiological and microrheological tests on diabetic subjects with and without intermittent claudication were performed in the present study. In total, 98 diabetic patients were included and divided into two groups: 20 patients (63.5 ± 8.8 years, 55% men, 45% women) had intermittent claudication, 78 patients (65.5 ± 9.3 years, 61.5% men, 38.5% women) were asymptomatic. Hand-held Doppler ultrasound examination, transcutaneous tissue partial oxygen pressure (tcpO2) measurement, Rydel-Seiffer tuning fork tests, and 6-min walk tests were performed, and erythrocyte aggregation was investigated. Ankle-brachial index (p < 0.02) and tcpO2, measured during provocation tests (p < 0.003) and the 6-min walk test (p < 0.0001), significantly deteriorated in the symptomatic group. A higher erythrocyte aggregation index and faster aggregate formation was observed in claudication patients (p < 0.02). Despite the statistically better results of the asymptomatic group, 13% of these patients had severe limb ischemia based on the results of tcpO2 measurement. Claudication can be associated with worse hemodynamic and hemorheological conditions in diabetic patients; however, severe ischemia can also develop in asymptomatic subjects. Non-invasive vascular tests can detect ischemia, which highlights the importance of early instrumental screening of the lower limbs.

Skeletal Muscle Bioenergetics in Critical Limb Ischemia and Diabetes

INTRODUCTION

Mitochondrial dysfunction is implicated in the metabolic myopathy accompanying peripheral artery disease (PAD) and critical limb ischemia (CLI). Type-2 diabetes mellitus (T2DM) is a major risk factor for PAD development and progression to CLI and may also independently be related to mitochondrial dysfunction. We set out to determine the effect of T2DM in the relationship between CLI and muscle mitochondrial respiratory capacity and coupling control.

METHODS

We studied CLI patients undergoing revascularization procedures or amputation, and non-CLI patients with or without T2DM of similar age. Mitochondrial respiratory capacity and function were determined in lower limb permeabilized myofibers by high-resolution respirometry.

RESULTS

Fourteen CLI patients (65 ± 10y) were stratified into CLI patients with (n = 8) or without (n = 6) T2DM and were compared to non-CLI patients with (n = 18; 69 ± 5y) or without (n = 19; 71 ± 6y) T2DM. Presence of CLI but not T2DM had a marked impact on all mitochondrial respiratory states in skeletal muscle, adjusted for the effects of sex. Leak respiration (State 2, P < 0.025 and State 4o, P < 0.01), phosphorylating respiration (P < 0.001), and maximal respiration in the uncoupled state (P < 0.001), were all suppressed in CLI patients, independent of T2DM. T2DM had no significant effect on mitochondrial respiratory capacity and function in adults without CLI.

CONCLUSIONS

Skeletal muscle mitochondrial respiratory capacity was blunted by ∼35% in patients with CLI. T2DM was not associated with muscle oxidative capacity and did not moderate the relationship between muscle mitochondrial respiratory capacity and CLI.

Machine Learning Models Predict the Need of Amputation and/or Peripheral Artery Revascularization in Hypertensive Patients Within 7-Years Follow-Up

Lower extremity amputation and requirement of peripheral artery revascularization are common outcomes of undiagnosed peripheral artery disease patients. In the current work, prediction models for the need of amputation or peripheral revascularization focused on hypertensive patients within seven years follow up are employed. We applied machine learning (ML) models using classifiers such as Extreme Gradient Boost (XGBoost), Random Forest (RF) and Adaptive Boost (AdaBoost), that will allow clinicians to identify the patients at risk of these two endpoints using simple clinical data. We used the non-interventional cohort of the getABI study in the primary care setting, selecting 4,191 hypertensive patients out of 6,474 patients with age over 65 years old and followed up for vascular events or death up to 7 years. During this follow up period, 150 patients underwent either amputation or peripheral revascularization or both. Accuracy, Specificity, Sensitivity and Area under the receiver operating characteristic curve (AUC) were estimated for each machine learning model. The results demonstrate Random Forest as the most accurate model for the prediction of the composite endpoint in hypertensive patients within 7 years follow-up, achieving 73.27 % accuracy.Clinical Relevance-This study assists clinicians to better predict and treat these serious outcomes, amputation and peripheral revascularization in hypertensive patients.

Myoglobinemia, Peripheral Arterial Disease, and Patient Mortality

BACKGROUND

Peripheral arterial disease (PAD) causes leg muscle damage due to inadequate perfusion and increases cardiovascular events and mortality 2- to 3-fold. It is unclear if PAD is a biomarker for high-risk cardiovascular disease or if skeletal muscle injury harms arterial health. The objective of this work is to test if serum myoglobin levels (myoglobinemia) are a marker of PAD, and if so, whether myoglobin impairs vascular health.

STUDY DESIGN

Patient blood samples were collected from PAD and control (no PAD) patients and interrogated for myoglobin concentrations and nitric oxide bioavailability. Patient mortality over time was captured from the medical record. Myoglobin activity was tested on endothelial cells and arterial function.

RESULTS

Myoglobin is a biomarker for symptomatic PAD and was inversely related to nitric oxide bioavailability; 200 ng/mL myoglobin in vitro increased endothelial cell permeability in vitro and decreased nitrate bioavailability. Ex vivo, 100 ng/mL myoglobin increased vascular tone in naive murine aortas approximately 1.5 times, impairing absolute vessel relaxation. In vivo, we demonstrated that myoglobinemia caused impaired flow-mediated dilation in a porcine model. Patients presenting with myoglobin levels of 100 ng/mL or greater had significantly more deaths than those with myoglobin levels of less than 100 ng/mL.

CONCLUSIONS

Using a combination of patient data, in vitro, ex vivo, and in vivo testing, we found that myoglobin is a biomarker for symptomatic PAD and a potent regulator of arterial health that can increase vascular tone, increase vascular permeability, and cause endothelial dysfunction, all of which may contribute to the vulnerability of PAD patients to cardiovascular events and death.

Protocol for the induction of hindlimb ischemia and isolation of muscle endothelial cells in mice

A mouse model of hindlimb ischemia is an important tool for studying diverse therapeutic approaches for vascularization with high surgical success and low mortality rates. Here, we present a protocol for the induction of hindlimb ischemia in mice, including the surgery procedure and steps to analyze blood perfusion in the ischemic area using a laser speckle contrast analyzer. We also detail the isolation of endothelial cells from thigh muscles using flow cytometry after ischemic surgery. For complete details on the use and execution of this protocol, please refer to Park et al. (2016).1.

Lower-limb peripheral arterial disease and amputations in people with diabetes: Risk factors, prognostic value and management

Lower-limb peripheral arterial disease (PAD), is a common manifestation of systemic atherosclerosis, resulting from a partial or complete obstruction of at least one lower-limb arteries. PAD is a major endemic disease with an excess risk of major cardiovascular events and death. It also leads to disability, high rates of lower-limb adverse events and non-traumatic amputation. In patients with diabetes, PAD is particularly frequent and has a worse prognosis than in patients without diabetes. The risk factors of PAD are comparable to those for cardiovascular disease. The ankle-brachial index is usually recommended to screen PAD despite its limited performance in patients with diabetes, affected by the presence of peripheral neuropathy, medial arterial calcification, incompressible arteries and infection. Toe brachial index and toe pressure emerge as alternative screening tools. The management of PAD requires strict control of cardiovascular risk factors including diabetes, hypertension and dyslipidaemia, the use of antiplatelet agents and lifestyle management, to reduce cardiovascular adverse events, but few randomized controlled trials have evaluated the benefits of these treatments in PAD. Several advances have been achieved in endovascular and surgical revascularization procedures, with obvious improvement in PAD prognosis. Further studies are required to increase our understanding of the pathophysiology of PAD and to evaluate the interest of different therapeutic strategies in the occurrence and progression of PAD in patients with diabetes. Here, we present a narrative and contemporary review to synthesize the key epidemiology findings, screening and diagnosis methods, and major therapeutic advances regarding PAD in patients with diabetes.

Quantitative model for assessment of lower-extremity perfusion in patients with diabetes

BACKGROUND

Although diabetic and atherosclerotic vascular diseases have different pathophysiological mechanisms, the screening methods currently used for diabetic lower-extremity vascular diseases are mainly based on the evaluation methods used for atherosclerotic vascular diseases. Thus, assessment of microvascular perfusion is of great importance in early detection of lower-extremity ischemia in diabetes.

PURPOSE

This cross-sectional study aimed to develop a quantitative model for evaluating lower-extremity perfusion.

METHODS

We recruited 57 participants (14 healthy participants and 43 diabetes patients, of which 16 had lower-extremity arterial disease [LEAD]). All participants underwent technetium-99 m sestamibi (99mTc-MIBI) scintigraphy and ankle-brachial index (ABI) examination. We derived two key perfusion kinetics indices named activity perfusion index (API) and basal perfusion index (BPI). This study was registered in ClinicalTrials.gov (URL: https://www.

CLINICALTRIALS

gov, NCT02752100).

RESULTS

The estimated limb perfusion values in our lower-extremity perfusion assessment (LEPA) model showed excellent consistency with the actual measured data. Diabetes patients showed reduced lower-extremity perfusion in comparison with the control group (BPI: 106.21 ± 11.99 vs. 141.56 ± 17.38, p < 0.05; API: 12.34 ± 3.27 vs. 14.56 ± 3.12, p < 0.05). Using our model, the reductions in lower-extremity perfusion could be detected early in approximately 96.30% of diabetes patients. Patients with LEAD showed more severe reductions in lower-extremity perfusion than diabetes patients without LEAD (BPI: 47.85 ± 20.30 vs. 106.21 ± 11.99, p < 0.05; API: 7.06 ± 1.70 vs. 12.34 ± 3.27, p < 0.05). Discriminant analysis using API and BPI could successfully screen all diabetes patients with LEAD with a sensitivity of 100% and specificity of 80.77%.

CONCLUSIONS

We established a LEPA model that could successfully assess lower-extremity microvascular perfusion in diabetes patients. This model has important application value for the recognition of early-stage LEAD in patients with diabetes.

Hospital-, Anesthesiologist-, Surgeon-, and Patient-Level Variations in Neuraxial Anesthesia Use for Lower Limb Revascularization Surgery: A Population-Based Cross-Sectional Study

BACKGROUND

Although neuraxial anesthesia may promote improved outcomes for patients undergoing lower limb revascularization surgery, its use is decreasing over time. Our objective was to estimate variation in neuraxial (versus general) anesthesia use for lower limb revascularization at the hospital, anesthesiologist, surgeon, and patient levels, which could inform strategies to increase uptake.

METHODS

Following protocol registration, we conducted a historical cross-sectional analysis of population-based linked health administrative data in Ontario, Canada. All adults undergoing lower limb revascularization surgery between 2009 and 2018 were identified. Generalized linear models with binomial response distributions, logit links and random intercepts for hospitals, anesthesiologists, and surgeons were used to estimate the variation in neuraxial anesthesia use at the hospital, anesthesiologist, surgeon, and patient levels using variance partition coefficients and median odds ratios. Patient- and hospital-level predictors of neuraxial anesthesia use were identified.

RESULTS

We identified 11,849 patients; 3489 (29.4%) received neuraxial anesthesia. The largest proportion of variation was attributable to the hospital level (50.3%), followed by the patient level (35.7%); anesthesiologists and surgeons had small attributable variation (11.3% and 2.8%, respectively). Mean odds ratio estimates suggested that 2 similar patients would experience a 5.7-fold difference in their odds of receiving a neuraxial anesthetic were they randomly sent to 2 different hospitals. Results were consistent in sensitivity analyses, including limiting analysis to patients with diagnosed peripheral artery disease and separately to those aged >66 years with complete prescription anticoagulant and antiplatelet usage data.

CONCLUSIONS

Neuraxial anesthesia use primarily varies at the hospital level. Efforts to promote use of neuraxial anesthesia for lower limb revascularization should likely focus on the hospital context.

Upgrading Monocytes Therapy for Critical Limb Ischemia Patient Treatment: Pre-Clinical and GMP-Validation Aspects

Advanced cell therapy medicinal products (ATMP) are at the forefront of a new range of biopharmaceuticals. The use of ATMP has evolved and increased in the last decades, representing a new approach to treating diseases that are not effectively managed with conventional treatments. The standard worldwide recognized for drug production is the Good Manufacturing Practices (GMP), widely used in the pharma production of synthesized drugs but applying also to ATMP. GMP guidelines are worldwide recognized standards to manufacture medicinal products to guarantee high quality, safety, and efficacy. In this report, we describe the pre-clinical and the GMP upgrade of peripheral blood mononuclear cell (PBMC) preparation, starting from peripheral blood and ending up with a GMP-grade clinical product ready to be used in patients with critical limb ischemia (CLI). We also evaluated production in hypoxic conditions to increase PBMC functional activity and angiogenic potential. Furthermore, we extensively analyzed the storage and transport conditions of the final product as required by the regulatory body for ATMPs. Altogether, results suggest that the whole manufacturing process can be performed for clinical application. Peripheral blood collected by a physician should be transported at room temperature, and PBMCs should be isolated in a clean room within 8 h of venipuncture. Frozen cells can be stored in nitrogen vapors and thawed for up to 12 months. PBMCs resuspended in 5% human albumin solution should be stored and transported at 4 °C before injection in patients within 24 h to thawing. Hypoxic conditioning of PBMCs should be implemented for clinical application, as it showed a significant enhancement of PBMC functional activity, in particular with increased adhesion, migration, and oxidative stress resistance. We demonstrated the feasibility and the quality of a GMP-enriched suspension of monocytes as an ATMP, tested in a clean room facility for all aspects related to production in respect of all the GMP criteria that allow its use as an ATMP. We think that these results could ease the way to the clinical application of ATMPs.

Below Knee Angioplasty Using Drug-Eluting Balloons in Patients with Critical Limb Ischemia with Six Months Follow-Up: Single-Center Experience at Tertiary Care Hospital

Aims and Objective The aim of this study was to evaluate 6 monthly safety and primary patency rates of drug-eluting balloons (DEB) angioplasty in below-the-knee (BTK) arteries in critical limb ischemia (CLI) patients.

Methods A prospective observational study was conducted over 2 years in a tertiary care center. A total of 25 patients with CLI were enrolled in this study. Inclusion criteria were patients presenting with CLI (Rutherford class 4 or greater), equal to or more than 50% luminal stenosis or occlusion of at least one tibial artery, and agreement to 6-month evaluation. Exclusion criteria were life expectancy less than 1 year, allergy to paclitaxel, and contraindication to antiplatelet treatment.

Follow-up was performed by clinical and Doppler assessment. The primary endpoint was a 6-month primary patency rate, and secondary endpoints were changes in the Rutherford class and incidence of major amputation. Restenosis rate is defined as a reduction in the luminal diameter by 50% or greater by duplex ultrasound.

Results Six-month primary patency was achieved in 19 (76%) patients. Both Rutherford category improvement and reduction in the percentage of stenosis after angioplasty were statistically significant (p-value <0.0001). At 6 months, better patency rates were seen among diabetics (88.8%) than smokers (69.2%). Limb salvage was observed in 24 (96%) patients with one major amputation (above the ankle).

Conclusion DEBs have shown safe and promising clinical outcomes with successful performance in infrapopliteal arteries in the short-term follow-up. DEB had a substantial 6-month primary patency rate. DEB angioplasty is a safe and effective treatment option for CLI patients with BTK vascular disease.

Association between Residential Distance from Home to Hospital and Amputation of a Lower Extremity among Peripheral Artery Disease Patients in Japan

Lack of access to care can lead to poor outcomes for patients with peripheral artery disease (PAD). We investigated the association between residential distance from home to hospital and amputation of the lower extremity among PAD patients in the Chiba peninsula, Japan. A retrospective cohort study with an average follow-up period of 2.96 years was conducted using data from 630 PAD patients who visited two hospitals in the Chiba peninsula, Japan, between 1 April 2010 to 31 March 2020. Information on disease status, residential address, and covariates was obtained from medical records. The association between amputation of a lower extremity, including toe amputation, and residential distance was evaluated by Cox proportional hazards model. Age, gender, Fontaine class, endovascular treatment, dialysis, diabetes mellitus, hypertension, dyslipidemia, current or past smoking, and aspirin use were adjusted. The median residential distance was 18.9 km (interquartile range, IQR: 22.1). Ninety-two patients (14.6%) underwent amputation of the lower extremity during the follow-up period. The longer residential distance was significantly associated with a higher risk of lower extremity amputation (hazard ratio per IQR = 1.35, 95% confidence interval, 1.01-1.82) after adjusting for covariates. Poorer access to a hospital, assessed as a longer residential distance from home to a hospital, was associated with amputation of the lower extremity among PAD patients.

Small extracellular vesicles of hypoxic endothelial cells regulate the therapeutic potential of adipose-derived mesenchymal stem cells via miR-486-5p/PTEN in a limb ischemia model

Background

Patients with critical limb ischemia (CLI) are at great risk of major amputation and cardiovascular events. Adipose-derived mesenchymal stem cell (ADSC) therapy is a promising therapeutic strategy for CLI, but the poor engraftment and insufficient angiogenic ability of ADSCs limit their regenerative potential. Herein, we explored the potential of human umbilical vein endothelial cells (HUVECs)-derived small extracellular vesicles (sEVs) for enhancing the therapeutic efficacy of ADSCs in CLI.

Results

sEVs derived from hypoxic HUVECs enhanced the resistance of ADSCs to reactive oxygen species (ROS) and further improved the proangiogenic ability of ADSCs in vitro. We found that the hypoxic environment altered the composition of sEVs from HUVECs and that hypoxia increased the level of miR-486-5p in sEVs. Compared to normoxic sEVs (nsEVs), hypoxic sEVs (hsEVs) of HUVECs significantly downregulated the phosphatase and tensin homolog (PTEN) via direct targeting of miR-486-5p, therefore activating the AKT/MTOR/HIF-1α pathway and influencing the survival and pro-angiogenesis ability of ADSCs. In a hindlimb ischemia model, we discovered that hsEVs-primed ADSCs exhibited superior cell engraftment, and resulted in better angiogenesis and tissue repair.

Conclusion

hsEVs could be used as a therapeutic booster to improve the curative potential of ADSCs in a limb ischemia model. This finding offers new insight for CLI treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01632-1.

Coronary artery calcium score and coronary computed tomography angiography predict one-year mortality in patients with type 2 diabetes and peripheral artery disease undergoing partial foot amputation

METHODS

This is a single-center prospective cohort study including 199 consecutive patients with T2D, PAD (mean age 62.3 ± 7.2 years; 62.8% males), and preoperative CACS and CCTA undergoing PFA and followed-up over 1 year.

RESULTS

Over a period of 1 year follow-up, a total of 35 (17.6%) participants died. The area under ROC curve to predict mortality for the CACS was 0.835 (95% CI:0.769-0.900), for CCTA 0.858 (95% CI:0.788-0.927). After adjustment for confounders, compared to no-stenosis on CCTA (reference), the risk of all-cause mortality in non-obstructive coronary atery disease (CAD) increased (HR = 1.38, 95% CI [0.75-12.86], p = .284), 1-vessel obstructive CAD (HR = 8.13, 95% CI [0.87-75.88], p = .066), 2-vessels (HR = 10.94, 95% CI [1.03-115.8], p = .047), and 3-vessels (HR = 45.73, 95% CI [4.6-454.7], p = .001) respectively. Increasing levels of CACS tended to be associated with increased risk of all-cause mortality (HR = 1.002, 95% CI [1.0-1.003], p = .061). 61/95 patients with obstructive CAD underwent coronary revascularization.

CONCLUSIONS

Coronary artery calcium score and CCTA have a high predictive value for 1-year all-cause mortality in T2D patients undergoing minor amputations and may be considered for preoperative risk assessment allowing timely preventive interventions.

Advances for the treatment of lower extremity arterial disease associated with diabetes mellitus

Lower extremity arterial disease (LEAD) is a major vascular complication of diabetes. Vascular endothelial cells dysfunction can exacerbate local ischemia, leading to a significant increase in amputation, disability, and even mortality in patients with diabetes combined with LEAD. Therefore, it is of great clinical importance to explore proper and effective treatments. Conventional treatments of diabetic LEAD include lifestyle management, medication, open surgery, endovascular treatment, and amputation. As interdisciplinary research emerges, regenerative medicine strategies have provided new insights to treat chronic limb threatening ischemia (CLTI). Therapeutic angiogenesis strategies, such as delivering growth factors, stem cells, drugs to ischemic tissues, have also been proposed to treat LEAD by fundamentally stimulating multidimensional vascular regeneration. Recent years have seen the rapid growth of tissue engineering technology; tissue-engineered biomaterials have been used to study the treatment of LEAD, such as encapsulation of growth factors and drugs in hydrogel to facilitate the restoration of blood perfusion in ischemic tissues of animals. The primary purpose of this review is to introduce treatments and novel biomaterials development in LEAD. Firstly, the pathogenesis of LEAD is briefly described. Secondly, conventional therapies and therapeutic angiogenesis strategies of LEAD are discussed. Finally, recent research advances and future perspectives on biomaterials in LEAD are proposed.

Impact of Modified H₂FPEF Score on Chronic Limb-Threatening Ischemia in Patients With Lower Extremity Artery Disease Who Underwent Endovascular Therapy

Background: Lower extremity artery disease (LEAD) is an arterial occlusive disease characterized by an insufficient blood supply to the lower limb arteries. The H₂FPEF score, comprising Heavy, Hypertensive, atrial Fibrillation, Pulmonary hypertension, Elder, and Filling pressure, has been developed to identify patients at high risk of heart failure (HF) with preserved ejection fraction. This study assessed the impact of modified H₂FPEF scores on chronic limb-threatening ischemia (CLTI) in patients with LEAD.

Methods and Results: This study was a prospective observational study. Because the definition of obesity differs by race, we calculated the modified H₂FPEF score using a body mass index >25 kg/m² to define obesity in 293 patients with LEAD who underwent first endovascular therapy. The primary endpoints were newly developed and recurrent CLTI. The secondary endpoint was a composite of events, including mortality and rehospitalization due to worsening HF and/or CLTI. The modified H₂FPEF score increased significantly with advancing Fontaine classes. Multivariate Cox proportional hazard analysis revealed that the modified H₂FPEF score was an independent predictor of newly developed and recurrent CLTI and composite events. The net reclassification index and integrated discrimination improvement were significantly improved by adding the modified H₂FPEF score to the basic predictors.

Conclusions: The modified H₂FPEF score was associated with LEAD severity and future CLTI development, suggesting that it could be a feasible marker for patients with LEAD.

Treatment of arterial calcification in patients with chronic limb threatening ischemia with etidronate: protocol of an investigator-initiated multicenter, double blind, placebo-controlled, randomized clinical trial

Background

Pathologic studies have shown that in patients with critical limb threatening ischaemia (CLTI) medial arterial calcifications are frequently found and may be responsible for aggravating the disease. These extensive calcifitcations are found not only in arteries of the leg but also in the coronary arteries and the aorta. The progression of these calcifications is fast and they stiffen the vessel wall and may thus increase the cardiovascular risk.

Reduction of progression of calcification may not only reduce the burden of CLTI but may also reduce the high residual cardiovascular risk. Medial calcifications have been halted by etidronate in other trials. Its potential to reduce the burden from peripheral vascular disease in CLTI and residual cardiovascular risk remains to be established.

Methods

This is an investigator-initiated multicenter, double blind, placebo-controlled, randomized trial comparing the effects of etidronate versus placebo in patients with CLTI.

Subjects will be randomized to either treatment with etidronate for 12 months (cyclical 20 mg/kg for 2 weeks on and 10 weeks off) orally or placebo for 12 months (in a similar routine).

The primary endpoint is the change in arterial calcification as quantified by CT-scan.

Secondary endpoints are the number of amputations above and below the ankle, mortality, number of vascular interventions and quality of life.

Discussion

Up to now, the inert end stage of vascular disease in patients with CLTI, has been considered calcification of vessel walls. We believe there is reason to reverse causation and hypothesize that calcification causes vascular disease. This reversal can be proven in a clinical trial if halting the calcification process improves the outcome of the patient. Therefore we use etidronate, a bisphosphate that has proven to stop the calcification in several rare monogenetic calcifying diseases. We aim to perform this mechanistic proof-of-concept study hopefully leading to a clinical outcome study later on.

Effects of Lower Limb Revascularization on the Microcirculation of the Foot: A Retrospective Cohort Study

Background: Current assessment standards in chronic limb-threatening ischemia (CLTI) focus on macrovascular function while neglecting the microcirculation. Multispectral near-infrared spectroscopy (NIRS) provides hemodynamic characteristics of the microcirculation (i.e., capillaries) and may be a powerful tool for monitoring CLTI and preventing extremity loss. The aims of this study were to (1) investigate the effects of lower limb revascularization on the microcirculation and (2) determine if macrovascular and microvascular assessments correlate. Methods: An observational, retrospective cohort study of 38 endovascular interventions in 30 CLTI subjects was analyzed pre- and post-intervention for arterial Doppler acceleration times (AcT; macrovascular) and NIRS metrics (microvascular). Pre-intervention ankle-brachial index (ABI) was also analyzed. Results: AcT significantly decreased (p = 0.009) while oxyhemoglobin (HbO) significantly increased (p < 0.04) after endovascular intervention, indicating treatment efficacy. However, macrovascular measurements (ABI, AcT) and NIRS metrics of oxygenation and perfusion did not correlate (p > 0.06, r2 < 0.15, n = 23) indicating that macro- and microvascular assessment are not congruent. Conclusion: These findings suggest that macrovascular and microvascular assessments can determine interventional efficacy in their corresponding vasculature. Their lack of correlation, however, suggests the need for simultaneous assessment as independent use may cause diagnostic information to be missed.

SS31 Ameliorates Oxidative Stress via the Restoration of Autophagic Flux to Protect Aged Mice From Hind Limb Ischemia

Background

Oxidative stress and impaired autophagic flux play important roles in the development of peripheral artery disease (PAD). SS31 is considered an important antioxidant peptide and autophagy regulator. We aimed to investigate the role of SS31 in PAD myopathy and its possible mechanism both in vivo and in vitro.

Methods

A hind limb ischemia (HLI) model was established with old C57BL/6 (14-month-old) mice. Mice in the SS31 group were intraperitoneally injected with SS31 (3 mg/kg) for 4 weeks. We examined skeletal muscle function and histomorphology, autophagy-related protein levels and reactive oxygen species (ROS) content. For the in vitro experiments, after C2C12 myotubes were treated with CoCl₂, SS31, and chloroquine (CQ) or rapamycin (RAPA), we measured ROS content, autophagy-related protein levels and antioxidant enzyme expression.

Results

SS31 treatment effectively enhanced the recovery of skeletal muscle function, alleviated skeletal muscle injury and suppressed mitochondrial ROS production in ischemic limbs. SS31 reduced apoptosis and oxidative stress, and SS31 restored impaired autophagic flux by inhibiting the AKT-mTOR pathway. In vitro studies showed that SS31 restored autophagic flux and improved oxidative stress in C2C12 cells. Moreover, phosphorylated AKT (p-AKT) and phosphorylated mTOR (p-mTOR) levels were reduced.

Conclusion

These experiments indicated that SS31 can inhibit oxidative stress by restoring autophagic flux to reverse hypoxia-induced injury in vivo and in vitro.

Impact of malnutrition and frailty on mortality and major amputation in patients with CLTI

OBJECTIVES

To understand the prevalence of malnutrition and its association with chronic limb-threatening ischemia (CLTI) outcomes; to clarify the differential impact of revascularization methods on outcomes; to assess the ability of the CLTI Frailty Risk Score (CLTI-FRS) to predict adverse events in patients hospitalized with CLTI.

BACKGROUND

Despite advances in the management of CLTI, a majority still undergo major amputation, and a minority heal within 6 months. There is a lack of validated assessment tools for the identification and management of frailty and malnutrition in these patients.

METHODS

Using the National Inpatient Sample from January 2012 to September 2015, we identified all patients with CLTI using International Classification of Diseases Ninth Edition Clinical Modification codes. The cohort was divided into three groups according to nutritional status. Multivariable regression analysis was used to analyze the interaction between malnutrition and outcomes of interest.

RESULTS

Of 1,414,080 CLTI-related hospitalizations, 163,835 (11.6%) were malnourished, 332,855 (23.5%) patients were frail, 917,390 (64.9%) were well-nourished. In-hospital mortality, major amputation, the average length of stay, and hospital costs were highest among malnourished or frail patients and lowest in well-nourished patients (p < 0.001). Malnourished and frail patients were observed to have lower rates of mortality with endovascular revascularization as compared to surgical (adjusted odds ratios: 0.675 [0.533-0.854; p = 0.001]).

CONCLUSION

Many patients with CLTI are malnourished or frail, and this is associated with mortality and amputation. Both malnourished and frail patients were observed to have a mortality benefit with a less invasive approach to revascularization. Better assessment of nutritional and frailty status of CLTI patients may guide therapy and help prevent amputation and death.

Contemporary Outcomes of Limb-Salvage Procedures Using Vascular Quality Initiative-Medicare Linked Data: Racial and Ethnic Disparities Persist

INTRODUCTION

Several reports have shown that ethnic and racial minorities with chronic limb-threatening ischemia (CLTI) are more likely to undergo major amputation. Whether this disparity is driven by limited access to care, statistical discrimination or biological factors remains a matter of debate. We sought to study the effect of race/ethnicity on short and long-term outcomes of limb-salvage procedures among patients with new onset CLTI.

METHODS

We identified all patients who underwent first time (open or endovascular) revascularization for CLTI between January 2010 and December 2016 in the Vascular Quality Initiative-Medicare linked database. These patients were divided into non-Hispanic whites (NHW) and racial/ethnic minority (REM) groups. Early end points included length of stay and operative mortality, while 2-year outcomes included major amputation, freedom from subsequent revascularization, number of limb salvage reinterventions and all-cause mortality. A sub-analysis comparing NHWs to Hispanics and NHWs to blacks was also performed.

RESULTS

Of 16,249 presenting with CLTI, 73.9% were non-Hispanic whites. Racial/ethnic minority patients were younger (mean age, 69.9 ± 11.3 years vs 74.2 ± 10.5 years; P < .001) and more likely to be female (45.9% vs 37.7%; P < .001). Other baseline differences included a higher rate of smoking history, coronary artery disease, chronic obstructive pulmonary disease and chronic kidney disease among non-Hispanic whites, whereas racial/ethnic minority patients were more likely to have diabetes and hypertension and more likely to present with tissue loss (78% vs 76.6%; P =.04). Preoperative ankle-brachial index and procedure type (endovascular vs open) were similar between the groups. On multivariable analysis, NHW's had a 13% increase in length of stay and a 25% decrease in operative mortality. In regard to 2-year outcomes, limb salvage estimates were 86% for the NHW group versus 77.1% for the REM group; P < .001. Comparison between the two groups showed similar rates of freedom from subsequent revascularization (67.9% vs 67.1%; P =.2). REM patients achieved higher rates of overall survival (70.3% vs 68.4%; P =.01) when compared to their white counterparts. Patients in the REM group were more likely to undergo more than two limb salvage reinterventions during follow-up (14.2% vs 8.6%; P < .001). After adjusting for potential confounders, REM patients had significantly higher odds of major amputation at 2 years (adjusted hazard ratio, 1.49; 95% confidence interval, 1.36-1.63; P < .001) CONCLUSIONS: In this Vascular Quality Initiative-Medicare matched study, racial and ethnic minority patients continue to face a higher major amputation risk despite having equivalent attempts at limb salvage. Further studies identifying risk factors and evaluating intervention strategies that may be more effective in preventing amputation in this particular population are warranted.

Reconstruction of infrarenal abdominal aortic occlusion using the Culotte stenting technique: a case report

Patients with clinically significant infrarenal abdominal aortic atherosclerosis are often encountered in the clinical practice of vascular and endovascular surgeons. In the absence of timely treatment, the ability to work and life quality of patients are sharply reduced, and in some cases, patients require limb amputation. Until recently, the only treatment option for such a lesion was an open surgery. However, a good skill level of endovascular surgeons and the device availability allow today to perform minimally invasive operations with comparable effectiveness and greater safety in comparison with open surgery. We present a case report of successful endovascular treatment of aortic occlusion involving the right and left common and external iliac arteries using Culotte stenting technique with further 12-month follow-up.

A Single-Center Study on the Outcomes of Target Limb Revascularization in Femoropopliteal Lesions Treated With Drug Coated Balloons and Bare Metal Stents

Purpose:

Multiple randomized controlled trials have shown that both drug coated balloons (DCBs) and bare metal stents (BMSs) significantly reduce restenosis in femoropopliteal lesions compared with plain balloon angioplasty. However, few studies have directly compared DCB and BMS treatments. Therefore, the goal of our study was to determine if the rate of target lesion revascularization (TLR) differs between DCB and BMS treatment at our center.

Materials and methods:

We performed a retrospective chart review of femoropopliteal interventions at a single center from 2009 to 2017. The intervention, patient and lesion characteristics, and TLR events were recorded. Exclusion criteria were loss of follow-up, death, bail-out stenting, and amputation within 60 days of treatment. Freedom from TLR was analyzed over a 3 year period with Kaplan-Meier survival curves. Cox hazard ratios were calculated to account for patient and lesion characteristics.

Results:

A total of 322 lesions (234 patients) treated with DCBs and 225 lesions (194 patients) treated with BMSs were included in this study. There were significant differences in baseline patient and lesion characteristics between groups—a greater proportion of women, patients with dyslipidemia, and lesions with popliteal involvement were treated with DCBs. There was no difference in the freedom from TLR between DCBs and BMSs. Accounting for patient and lesion characteristics, there was still no difference between DCBs and BMSs on the hazard of TLR. While our analysis did not detect a difference in the rate of TLR, there was a significant difference in the type of TLR. Compared with DCBs, a greater proportion of lesions initially treated with BMSs were retreated via surgical bypass rather than endovascular intervention, suggesting that lesions treated with DCBs may be more amenable to future endovascular intervention.

Conclusion:

Our retrospective analysis showed no difference in the rate of TLR between lesions treated with DCBs and BMSs. However, DCBs were more often used in complicated lesions involving popliteal arteries and may also allow for easier endovascular reintervention.

Relationship between Mean Platelet Volume and Critical Limb Ischemia in Diabetes Mellitus Patients

The prevalence of diabetes mellitus continues to increase from year to year. Critical limb ischemia (CLI) is one of the complications of diabetes mellitus with a high mortality rate and requires amputation if not treated properly. Mean platelet volume (MPV) is an indicator of platelet activation and is expected to be a predictor of CLI in diabetes mellitus patients. This article investigates the relationship between MPV and the incidence of CLI in diabetes mellitus patients. This case-control study was conducted using the vascular registry of Dr. Sardjito Hospital, Yogyakarta, Indonesia, from January 2016 to December 2016. The relationship between MPV and the incidence of CLI was analyzed using bivariate and multivariate analysis. There was a significant association between MPV and incidence of CLI in diabetes mellitus patient both on bivariate analysis ( p  = 0.035) and multivariate analysis ( p  = 0.029). Diabetes mellitus patients with MPV values of ≥ 9.8 fl had a protective effect to prevent the incidence of CLI (bivariate analysis: odds ratio [OR] = 0.366, 95% confidence interval [CI] = 0.142-0.943; multivariate analysis: adjusted OR = 0.288, 95% CI = 0.09-0.88). Confounding factors such as sex, age, obesity, and use of antiplatelet agents were not associated with the incidence of CLI ( p  > 0.05). Meanwhile, history of dyslipidemia as a confounding factor was significantly associated with the incidence of CLI ( p  < 0.05). Low MPV was found to be significantly associated with the incidence of CLI in diabetes mellitus patients.

Endovascular interventions in patients with multilevel steno-occlusive lesions of the infrarenal aortic arteries

Peripheral artery diseases are a worldwide medical and social problem. Approximately 30 % of patients with critical limb ischemia will undergo amputations and 25 % will die after 1 year. These patients require reconstructive and angioplastic interventions to preserve the limb. The aim of the study is to compare the effectiveness of different endovascular surgical technologies in patients with multilevel steno-occlusive lesions of the infrarenal aortic arteries. Materials and methods. Among 243 endovascular interventions, 51 patients were presented with multilevel steno-occlusive lesions of the infrarenal aortic arteries as a result of atherosclerosis obliterans. 42 patients (82.4 %) had two-level lesions and 9 (17.6 %) had three-level lesions. Results. Among 42 patients with a two-level lesion, 29 (56.9 %) ones had femoral arterial segment affection in combination with tibial artery affection. 13 (25.5 %) patients suffered from the lesion of the iliac segment in combination with the affection of the femoral segment arteries. In 9 (17.6 %) patients the lesions of three or more levels were determined: an iliac segment in combination with femoral and popliteal arteries – in 4 patients, and in 2 patients there were lesions of the femoral, popliteal and tibial segments, in 3 patients there was a lesion of the iliac, femoral, popliteal and tibial-foot segments in different degrees of severity. 7 balloon angioplasties and 13 stenting procedures were performed in two and three-level lesions in which the iliac arterial segment was affected. Only balloon angioplasty was used to revascularize the infraingvinal arterial segments. In the early postoperative period, the complications included thrombosis appeared in 6 patients. It was possible to restore the blood flow and save the limb only in 3 persons. For the other 3 ones, the attempts to restore the patency of the arteries were unsuccessful and resulted in the amputation of the lower extremity. Mortality in the early postoperative period was 3.9 % (2 death due to myocardial infarction). Conclusions. The persons with multilevel steno-obstructive lesions of the infrarenal aortic arteries are the most difficult category of patients with CLI. The surgical method of choice for patients with multilevel steno-occlusive lesions is the endovascular angioplasty with or without stenting.

Contemporary outcomes of concomitant suprainguinal bypass with infrainguinal revascularization procedures in patients with chronic limb-threatening ischemia

OBJECTIVE

Combined suprainguinal and infrainguinal revascularization is sometimes necessary in the treatment of patients with chronic limb-threatening ischemia (CLTI). However, data on outcomes of concomitant revascularization procedures are lacking. We studied the outcomes of patients with CLTI who underwent suprainguinal bypass (SIB) alone, SIB with concomitant infrainguinal bypass (IIB), and SIB with concomitant infrainguinal peripheral endovascular intervention (IIPVI).

METHODS

We reviewed all patients in the Vascular Quality Initiative with CLTI who underwent SIB from January 2010 to June 2020. Logistic regression, Kaplan-Meier survival estimates, log-rank tests, and Cox regression were used to analyze outcomes. Outcomes were 30-day mortality, perioperative myocardial infarction, perioperative major amputation, 1-year amputation-free survival, and 5-year survival.

RESULTS

Of 8037 patients included, 81.3% (n = 6537) underwent SIB alone, 9.7% (n = 783) underwent SIB+IIB, and 8.9% (n = 717) underwent SIB+IIPVI. The indication for surgery was rest pain in 5040 (62.5%) and tissue loss in 3031 (37.6%). There were no significant differences in 30-day mortality and perioperative myocardial infarction rates. However, there was 2.8-fold increased odds of perioperative major amputation in both SIB+IIPVI (odds ratio [OR], 2.76; 95% confidence interval [CI], 1.30-5.88; P = .008) and SIB+IIB (OR, 2.79; 95% CI, 1.38-5.54; P = .004) among patients with rest pain as compared with SIB alone. Comparing SIB+IIPVI with SIB alone, there were no significant differences in 1-year freedom from amputation and amputation-free survival. SIB+IIPVI was associated with a 27% increased risk of 5-year mortality (hazard ratio [HR], 1.27; 95% CI, 1.03-1.55; P = .035). Compared with SIB alone, SIB+IIB was associated with 97% increased risk of 1-year major amputation among patients with rest pain (HR, 1.97; 95% CI, 1.06-3.69; P = .033), but a 47% decreased risk of 1-year major amputation or death for patients with tissue loss (HR, 0.53; 95% CI, 0.37-0.78; P = .001). SIB+IIPVI, compared with SIB+IIB, was associated with a two-fold increased risk of 1-year major amputation or death (HR, 2.04; 95% CI, 1.04-2.23), P = .003) and a 52% increased risk of 5-year mortality (HR,1.52; 95% CI, 1.04-2.24; P = .032) among patients with tissue loss.

CONCLUSIONS

This study shows that SIB with concomitant infrainguinal revascularization in patients with rest pain is associated with an increased risk of amputation, whereas SIB+IIB in patients with tissue loss is associated with decreased risk of amputation or death. SIB+IIB outperformed SIB+IIPVI in patients with tissue loss. SIB with infrainguinal revascularization should be limited in patients with rest pain in line with current guidelines, but SIB+IIB may be preferred in patients with tissue loss.

Quantifying tissue perfusion after peripheral endovascular procedures: Novel tissue perfusion endpoints to improve outcomes

Peripheral artery disease (PAD) is a flow-limiting condition caused by narrowing of the peripheral arteries typically due to atherosclerosis. It affects almost 200 million people globally with patients either being asymptomatic or presenting with claudication or critical or acute limb ischemia. PAD-affected patients display increased mortality rates, rendering their management critical. Endovascular interventions have proven crucial in PAD treatment and decreasing mortality and have significantly increased over the past years. However, for the functional assessment of the outcomes of revascularization procedures for the treatment of PAD, the same tests that have been used over the past decades are still being employed. Those only allow an indirect evaluation, while an objective quantification of limb perfusion is not feasible. Standard intraarterial angiography only demonstrates post-intervention vessel patency, hence is unable to accurately estimate actual limb perfusion and is incapable of quantifying treatment outcome. Therefore, there is a significant necessity for real-time objectively measurable procedural outcomes of limb perfusion that will allow vascular experts to intraoperatively quantify and assess outcomes, thus optimizing treatment, obviating misinterpretation, and providing significantly improved clinical results. The purpose of this review is to familiarize readers with the currently available perfusion-assessment methods and to evaluate possible prospects.

Autologous cell therapy in diabetes‑associated critical limb ischemia: From basic studies to clinical outcomes (Review)

Cell therapy is becoming an attractive alternative for the treatment of patients with no‑option critical limb ischemia (CLI). The main benefits of cell therapy are the induction of therapeutic angiogenesis and neovascularization that lead to an increase in blood flow in the ischemic limb and tissue regeneration in non‑healing cutaneous trophic lesions. In the present review, the current state of the art of strategies in the cell therapy field are summarized, focusing on intra‑operative autologous cell concentrates in diabetic patients with CLI, examining different sources of cell concentrates and their mechanisms of action. The present study underlined the detrimental effects of the diabetic condition on different sources of autologous cells used in cell therapy, and also in delaying wound healing capacity. Moreover, relevant clinical trials and critical issues arising from cell therapy trials are discussed. Finally, the new concept of cell therapy as an adjuvant therapy to increase wound healing in revascularized diabetic patients is introduced.

Successful Revascularization of Infrapopliteal Chronic Total Occlusions Using the Plantar Arch as a Conduit and Retrograde Pedal Access

Background: With the rising prevalence of critical limb ischemia (CLI), the pedal-plantar loop technique and retrograde access may be needed to increase interventional success.

Case Report: A 63-year-old female with severe peripheral artery disease presented with a 2-month nonhealing wound on the dorsum of her left foot despite wound care. We inserted a 65-cm Destination Guiding Sheath and crossed the right superficial femoral artery (SFA) chronic total occlusion (CTO) that we initially treated with a 4.0-mm Ultraverse balloon. We attempted unsuccessfully to cross the distal anterior tibial artery into the dorsalis pedis artery. We obtained antegrade access of the posterior tibial artery at the level of the ankle with a 2.9-French Cook pedal access kit. We inserted a 90-cm CXI catheter with a 0.014 Fielder XT wire and used the lateral plantar artery as a conduit to cross the dorsalis pedis artery and distal anterior tibial artery CTO with retrograde wire manipulation via lateral plantar artery. Finally, we performed distal anterior tibial and dorsalis pedis CTO balloon angioplasty with a 2.5 × 220-mm Ultraverse balloon and performed SFA percutaneous transluminal angioplasty and stenting with a 7.0 × 120-mm Zilver PTX stent, postdilated with a 6.0-mm Ultraverse balloon. We successfully established in-line flow to the foot with 3-vessel runoff. The patient's wound healed in a month.

Conclusion: Retrograde pedal access can improve the success rate of recanalization of below-the-knee disease in patients with CLI.

Mortality Rates After Paclitaxel-Coated Device Use in Patients With Occlusive Femoropopliteal Disease: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials

PURPOSE

A late increased mortality risk has been reported in a summary level meta-analysis of patients with femoropopliteal artery occlusive disease treated with paclitaxel-coated angioplasty balloons and stents. However, at the longer follow up timepoints that analysis was limited by small trial numbers and few participants. The aim of this study was to report an updated summary level risk of all-cause mortality after treatment with paclitaxel-coated devices in that same patient group.

MATERIALS AND METHODS

We performed a systematic review and meta-analysis of randomized controlled trials to investigate the mortality outcomes associated with paclitaxel-coated devices used to treat patients with occlusive disease of femoropopliteal arteries (last search date December 10, 2020). The single primary endpoint was all-cause mortality.

RESULTS

We identified 34 randomized controlled trials (7654 patients; 84% intermittent claudication). There were 622 deaths among 4147 (15.0%) subjects in the paclitaxel device group and 475 deaths among 3507 (13.5%) subjects in the noncoated control group [relative risk ratio (RR) 1.07, 95% confidence interval (CI) 0.96 to 1.20, p=0.20, I²=0%). All-cause mortality was similar between groups at 12 months (34 studies, 7654 patients; RR 0.99, 95% CI 0.81 to 1.22, p=0.94, I²=0%), 24 months (20 studies, 3799 patients; RR 1.16, 95% CI 0.87 to 1.55, p=0.31, I²=0%), and 60 months (9 studies, 2288 patients; RR 1.19, 95% CI 0.98 to 1.45, p=0.08, I²=0%).

CONCLUSION

This updated meta-analysis with included additional trials and larger patient numbers shows no evidence of increased risk of all-cause mortality in patients treated with paclitaxel-coated devices, compared with uncoated devices for femoropopliteal disease at all time points to 60 months. There is therefore no justification to limit their use, or alter regulatory body follow-up recommendations in this patient population.

SYSTEMATIC REVIEW REGISTRATION

CRD42020216140.

Long-term outcomes of peripheral arterial disease patients with significant coronary artery disease undergoing percutaneous coronary intervention

Background

Patients with peripheral arterial disease (PAD) have known to a high risk of cardiac mortality. However, the effectiveness of the routine evaluation of coronary arteries such as routine coronary angiography (CAG) in PAD patients receiving percutaneous transluminal angioplasty (PTA) is unclear.

Methods

A total of 765 consecutive PAD patients underwent successful PTA and 674 patients (88.1%) underwent routine CAG. Coronary artery disease (CAD) was defined as angiographic stenosis ≥70%. Patients were divided into three groups; 1) routine CAG and a presence of CAD (n = 413 patients), 2) routine CAG and no CAD group (n = 261 patients), and 3) no CAG group (n = 91 patients). To adjust for any potential confounders that could cause bias, multivariable Cox-proportional hazards regression and propensity score matching (PSM) analysis was performed. Clinical outcomes were evaluated by Kaplan-Meier curved analysis at 5-year follow-up.

Results

In this study, the 5-year survival rate of patients with PAD who underwent PTA was 88.5%. Survival rates were similar among the CAD group, the no CAD group, and the no CAG group, respectively (87.7% vs. 90.4% vs. 86.8% P = 0.241). After PSM analysis between the CAD group and the no CAD group, during the 5-year clinical follow-up, there were no differences in the incidence of death, myocardial infarction, strokes, peripheral revascularization, or target extremity surgeries between the two groups except for repeat PCI, which was higher in the CAD group than the non-CAD group (9.3% vs. 0.8%, P<0.001).

Conclusion

PAD patients with CAD were expected to have very poor long-term survival, but they are shown no different long-term prognosis such as mortality compared to PAD patients without CAD. These PAD patients with CAD had received PCI and/or optimal medication treatment after the CAG. Therefore a strategy of routine CAG and subsequent PCI, if required, appears to be a reasonable strategy for mortality risk reduction of PAD patients. Our results highlight the importance for evaluation for CAD in patients with PAD.