What is Happening in the Ambulatory Space? Past Challenges and Future Directions.

Despite reimbursement pressures and scrutiny of procedural appropriateness, the demand for peripheral vascular ambulatory services remains strong. Improvements in minimally invasive technologies, coupled with a supportive regulatory environment and considerable preference for ambulatory services among purchasers, patients, and providers, have resulted in the rapid proliferation of ambulatory facilities in a number of markets. Emerging ecosystem dynamics, notably the rapid growth of Medicare Advantage and the growing presence of private equity and venture capital within healthcare, will likely have an impact on future growth trends but will not fundamentally alter the incentives driving the ambulatory shift. Indeed, it is likely that the dynamics currently at work within peripheral vascular services will become come to characterize a variety of other services, as more care shifts away from the hospital.

Establishing a Critical Limb Ischemia Outpatient Center: Separating Facts from Myth.

Critical Limb Ischemia or chronic limb-threatening ischemia represents the end stage of peripheral artery disease where arterial flow is compromised to the lower extremities and risk of limb loss may become imminent. Revascularization of lower extremities is one of the cornerstones of limb salvage and amputation prevention. Establishing centers of high quality CLI therapy requires creating different foundational pillars in order to be successful. This article discusses critical limb ischemia center creation from the perspective of critical limb ischemia therapists working in an outpatient setting.

Revisiting the role of trimetazidine for peripheral artery disease: a systematic review with meta-analysis.

OBJECTIVE: To examine the impact of trimetazidine on skeletal muscle function in patients suffering from peripheral artery disease. METHODS: The systematic review was conducted from July 20 to November 22, 2022, in line with the Preferred Reporting Items for Systematic Review and Meta-Analysis and comprised search for interventional studies on MEDLINE, ProQuest, Scopus and ScienceDirect databases using key words "peripheral artery disease" and "trimetazidine" or their synonyms. The cut-off date for the search was July 21, 2022. Clinical parameters, including Ankle-Brachial Index, Maximum Walking Distance, Maximum Walking Time and Pain Onset Time, were analysed both narratively and quantitatively whenever possible. RESULTS: Of the 587 studies initially identified, 12(2%) were shortlisted. Of them, 2(16.7%) qualified for detailed analysis, comprising 172 patients with intermittent claudication. There was no significant difference between the examined groups' Ankle-Brachial Index values at baseline and post-intervention (p=0.83). Maximum Walking Distance improvement was significantly higher (p=0.0006) in trimetazidine group compared to control group. Maximum Walking Time MWT and Pain Onset Time were significantly different between control and trimetazidine groups (p<0.05). CONCLUSIONS: Trimetazidine's anti-ischaemic effect in peripheral artery disease patients improved Maximum Walking Distance, while it had no significant influence on Ankle-Brachial Index. Well-designed studies addressing the issue are needed.

A latent bleeding complication in ipsilateral common femoral puncture involving delayed diagnosis: a case report.

BACKGROUND: The trans femoral ipsilateral approach is often adopted for endovascular treatment (EVT) for better steerability of guidewires or better device deliverability. However, contrary to the trans femoral contralateral approach, ipsilateral antegrade puncture sometimes causes peculiar bleeding complications. CASE PRESENTATION: A 76-year-old female underwent EVT for chronic occlusion of the left superficial femoral artery (SFA) via the ipsilateral antegrade approach. After guidewire passage, we inflated the drug-coated balloons, but angiography showed blood flow stasis at the mid segment of the SFA. We also ensured prolonged balloon inflation, which resulted in favorable blood flow. While trying to ensure hemostasis, the blood pressure remained decreased, but neither bleeding nor superficial hematoma were observed at the puncture site. After hemostasis was achieved, we removed the surgical drape and noticed a swelling in the mid-portion of the thigh, distant from the puncture point. We then approached the left common femoral artery (CFA) contralaterally. Angiography showed continuous bleeding from a little bit distally to the sheath insertion point that was spreading through an intramuscular space. We stopped the bleeding with balloon tamponade inside the CFA. Angiography after hemostasis demonstrated blood flow stasis at the mid-segment of the SFA, similarly as that seen before. We confirmed compression of the SFA by a large hematoma using both intra- and extra- vascular ultrasound. Therefore, we deployed a self-expandable stent at the compressed SFA position. Finally, we achieved favorable blood flow on angiography. CONCLUSION: We encountered a case that latent bleeding unrecognized in the surgical field persisted while prolonged inflation of DCB was conducted at just proximal SFA. We could have avoided bailout stenting by noticing the bleeding incident in a timely manner. Prediction and prevention are essential for all kinds of procedural complications in EVT.

Correlation of ankle-wrist pressure index with ankle-brachial pressure index to assess lower limb perfusion in diabetic foot ulcer: a pilot study.

OBJECTIVE: The presence of peripheral artery disease (PAD) in patients with diabetic foot ulcers (DFUs) is a significant risk factor for chronicity and amputation. Ankle-brachial pressure index (ABPI) is a screening tool for PAD. Brachial systolic pressure measurement, used as a denominator in the calculation of ABPI, produces inaccurate results in patients with obesity and the presence of heavy clothing. The wrist, however, is easily accessible, and the ankle-wrist pressure index (AWPI), if comparable with ABPI, may be useful in screening selected patients. This study aimed to assess the efficacy of AWPI in diagnosing perfusion in DFUs and compare it to ABPI in patients with DFUs. METHOD: ABPI and AWPI were calculated by measuring systolic blood pressure in the arteries of the ankle, arm and wrist with a handheld Doppler. Actual perfusion was determined by the presence or absence of PAD by duplex ultrasound. RESULTS: A total of 46 lower extremities in 41 patients were studied. The prevalence of PAD was 61%. Duplex ultrasound confirmed that the sensitivity of ABPI and AWPI in detecting PAD in patients with DFUs was 67.9% and 71.4% respectively, whereas the specificity of ABPI and AWPI was 94.4% and 88.9% respectively. On receiver operating characteristic analysis, the area under the curve of ABPI and AWPI was 0.804 and 0.795, respectively. A statistically significant positive correlation between ABPI and AWPI was found (r=0.986; p<0.001). CONCLUSION: There was a good correlation between ABPI and AWPI over a wide range of values. ABPI and AWPI may have a similar role in predicting perfusion in patients with DFUs. AWPI could be used in place of ABPI in selected patients in whom measuring ABPI may be difficult. DECLARATION OF INTEREST: The authors have no conflicts of interest to declare.

Pathological Changes in the Gastrocnemius Muscle throughout Hind Limb Ischemia Modeling in Rats.

We present a two-stage model for the study of chronic hind limb ischemia in rats. In the area of ischemia, sclerotic changes with atrophic rhabdomyocytes and reduced vascularization were revealed. CD31 expression in the endothelium increased proportionally to the number of vessels in the ischemic zone, and at the same time, focal expression of ßIII-tubulin was detected in the newly formed nerve fibers. These histological features are equivalent to the development of peripheral arterial disease in humans, which allows using our model in the search for new therapeutic strategies.

Current Opinion on Diagnosis of Peripheral Artery Disease in Diabetic Patients.

Peripheral arterial disease (PAD) prevalence and diabetes mellitus (DM) prevalence are continuously increasing worldwide. The strong relationship between DM and PAD is highlighted by recent evidence. PAD diagnosis in diabetic patients is very important, particularly in patients with diabetic foot disease (DFD); however, it is often made difficult by the characteristics of such diseases. Diagnosing PAD makes it possible to identify patients at a very high cardiovascular risk who require intensive treatment in terms of risk factor modification and medical therapy. The purpose of this review is to discuss the diagnostic methods that allow for a diagnosis of PAD in diabetic patients. Non-invasive tests that address PAD diagnosis will be discussed, such as the ankle-brachial index (ABI), toe pressure (TP), and transcutaneous oxygen pressure (TcPO2). Furthermore, imaging methods, such as duplex ultrasound (DUS), computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA), are described because they allow for diagnosing the anatomical localization and severity of artery stenosis or occlusion in PAD. Non-invasive tests will also be discussed in terms of their ability to assess foot perfusion. Foot perfusion assessment is crucial in the diagnosis of critical limb ischemia (CLI), the most advanced PAD stage, particularly in DFD patients. The impacts of PAD diagnosis and CLI identification in diabetic patients are clinically relevant to prevent amputation and mortality.

Role of long noncoding RNAs in diabetes-associated peripheral arterial disease.

Diabetes mellitus (DM) is a metabolic disease that heightens the risks of many vascular complications, including peripheral arterial disease (PAD). Various types of cells, including but not limited to endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and macrophages (MΦs), play crucial roles in the pathogenesis of DM-PAD. Long non-coding RNAs (lncRNAs) are epigenetic regulators that play important roles in cellular function, and their dysregulation in DM can contribute to PAD. This review focuses on the developing field of lncRNAs and their emerging roles in linking DM and PAD. We review the studies investigating the role of lncRNAs in crucial cellular processes contributing to DM-PAD, including those in ECs, VSMCs, and MΦ. By examining the intricate molecular landscape governed by lncRNAs in these relevant cell types, we hope to shed light on the roles of lncRNAs in EC dysfunction, inflammatory responses, and vascular remodeling contributing to DM-PAD. Additionally, we provide an overview of the research approach and methodologies, from identifying disease-relevant lncRNAs to characterizing their molecular and cellular functions in the context of DM-PAD. We also discuss the potential of leveraging lncRNAs in the diagnosis and therapeutics for DM-PAD. Collectively, this review provides a summary of lncRNA-regulated cell functions contributing to DM-PAD and highlights the translational potential of leveraging lncRNA biology to tackle this increasingly prevalent and complex disease.

The bodyweight walking distance product and its relationship with clinical markers in patients with symptomatic peripheral artery disease.

PURPOSE: The six-minute walk test (6MWT) is extensively employed to evaluate gait impairment in patients with symptomatic peripheral artery disease (PAD) and has been associated with different health outcomes. However, various approaches exist for calculating and interpreting the six-minute test in order to address the needs of patients more effectively. Therefore, we investigated how these different approaches correlate with functional capacity and cardiovascular health in patients with symptomatic PAD. METHODS: In total, 227 PAD patients [65.2% men and 67 (13) y.o.] were included in this cross-sectional study. The 6MWT was performed along a 30-meter corridor and the distance was expressed in three ways: absolute (described as the meters walked during the test), relativized (based on the results of the 6MWT in healthy individuals), and DW (multiplying the body weight in kilograms by the absolute distance in the 6MWT). A functional capacity z-score was calculated using the results of the handgrip strength test, 4-meter walking test, and sit-and-stand test. A cardiovascular parameter z-score was calculated with data on brachial and central blood pressure, the low-frequency component/high-frequency component ratio, and carotid-femoral pulse wave velocity. RESULTS: The absolute (b = 0.30, 95%CI: 18-0.43, R² = 0.11, p < 0.001) and DW (b = 0.40, 95%CI: 27-0.53, R² = 0.17, p < 0.001) measures were related to functional capacity, independently of sex, age, and the ankle-arm index of the patients. Neither absolute nor DW were related to cardiovascular health. The relativized measure was not associated with either functional capacity or cardiovascular health. CONCLUSION: In patients with symptomatic PAD, absolute and DW measures are related to functional capacity, but not cardiovascular function.

Perfusion increase in foot angiosomes: Comparison between direct and indirect revascularization of crural arteries.

BACKGROUND AND AIMS: In retrospective studies, wound healing and leg salvage have been better if revascularization is targeted to the crural artery supplying arterial flow to the wound angiosome. No data exist on how revascularization changes the blood flow in foot angiosomes. The aim of this study was to evaluate the change in perfusion after infrapopliteal artery revascularization in all foot angiosomes and to compare directly revascularized (DR) angiosomes to the indirectly revascularized (IR) angiosomes. METHODS: In this prospective study, foot perfusion was measured with indocyanine green fluorescence imaging (ICG-FI) before and after either surgical or endovascular below-knee revascularization. According to angiograms, we divided the foot angiosomes into DR and IR angiosomes. Furthermore, in a subanalysis, the IR angiosomes were graded as IR_Coll+ angiosomes if there were strong collaterals arising from the artery which was revascularized, and as IR_Coll- angiosomes if strong collaterals were not seen. RESULTS: A total of 72 feet (28 bypass, 44 endovascular revascularizations) and 282 angiosomes were analyzed. Surgical and endovascular revascularization increased perfusion significantly in both DR and IR angiosomes. After bypass surgery, the increase in DR angiosomes was 55 U and 53 U in IR angiosomes; there were no significant difference in the perfusion increase between IR and DR angiosomes. After endovascular revascularization, perfusion increased significantly more, 40 U, in DR angiosomes compared to 26 U in IR angiosomes (p < 0.05). In the subanalysis of IR angiosomes, perfusion increased significantly after surgical bypass regardless of whether strong collaterals were present or not. After endovascular revascularization, however, a significant perfusion increase was noted in the IR_Coll+ but not in the IR_Coll- subgroup. CONCLUSION: Open revascularization increased perfusion equally in DR and IR angiosomes, whereas endovascular revascularization increased perfusion significantly more in DR than in IR angiosomes. Strong collateral network may help increase perfusion in IR angiosomes.

Percutaneous intervention versus surgery in the treatment of common femoral artery lesions: study protocol for the prospective, multi-center, randomized PESTO-CFA trial.

BACKGROUND: Endovascular therapy has become established as a first-line therapy in most arterial regions. However, open vascular surgery (endarterectomy) remains the treatment of choice for common femoral artery (CFA) lesions. The aim of this study is to investigate the acute and mid-term results of directional atherectomy plus drug-coated balloon (DCB) in comparison to endarterectomy in treatment of de novo arteriosclerotic CFA lesions. METHODS: This prospective, randomized, multicenter non-inferiority study will enroll 306 participants with symptomatic (Rutherford category 1 to 5) de novo stenosis of the CFA including the bifurcation. Patients eligible for both treatment groups could be included in this 1:1 randomized trial. Primary efficacy endpoint is patency of the target lesion at 12 months defined as restenosis < 50% without the need of clinically driven target lesion revascularization (cdTLR). Primary safety endpoint is a combined endpoint including death, myocardial infarction, major or minor amputation of the target limb, and peri-procedural complications at 30 days. Secondary endpoints include primary patency of the target lesion at 6 and 24 months, secondary patency, cdTLR 6, 12, and 24 months, change in ankle-brachial index, and Rutherford-Becker class at 6, 12, and 24 months. Limb salvage, change in quality of life measured by Walking Impairment Questionnaire, and major adverse events including death, myocardial infarction, and minor or major amputation of the target limb will be determined at 6, 12, 24, and 36 months. DISCUSSION: Endovascular treatment of CFA lesions is still a matter of debate. Few studies compared modern endovascular therapy methods against the so-called gold standard surgical endarterectomy so far. Based on recent positive results, this study aims to confirm non-inferiority of a "leaving nothing behind" endovascular approach combining directional atherectomy and DCB compared to surgical therapy. TRIAL REGISTRATION: ClinicalTrials.gov NCT02517827.

Development of a Tetherless Bioimpedance Device That Uses Morphologic Changes to Predict Blood Flow Restrictions Mimicking Peripheral Artery Disease Progression.

A tetherless multi-targeted bioimpedance device was designed, modeled, built, and tested for measuring arterial pulse and, using morphological analysis, its potential for monitoring blood flow restrictions that mimic Peripheral Artery Disease (PAD) was assessed across multiple peripheral arteries. Specifically, we first developed a small form factor, tetherless, bioimpedance device, based on high-frequency structure simulator (HFSS) simulations. After designing and building the device we then tested it in vivo on human subjects on multiple arteries and found that we did not need to modify the gain on the device compared to the bench top system. Further, it was found that changes in the morphology of the bioimpedance signal over time, depicted through the ratio of the first and second harmonic in the signal frequency, could be used to predict blood flow restrictions that mimic peripheral artery disease (PAD). The HFSS simulations helped guide the modulation frequency selection and the placement of the bioimpedance electrodes. We built the device and compared it to two commercially available bioimpedance devices and it was shown to demonstrate a distinct advantage in its multi-target capability, enabling more accurate pulse measurements from different arteries without the need for tuning the circuit for each artery. Comparing the ratio of the 1st and 2nd harmonics as a function of the blood flow restriction, the two commercial devices showed a maximum error across arteries of between 22% and 27% depending on the measurement location, whereas our system consistently displayed a stable value of just below 4%. With this system, there is the potential for comprehensive and personalized medical examinations for PAD at the point of care (POC).

The PAD-adapted 30-20-10 during Nordic walking: A new exercise training session in patients with symptomatic peripheral artery disease.

This study aimed to investigate the feasibility of a peripheral artery disease (PAD)-adapted 30-20-10 Nordic walking session in patients with symptomatic PAD and to compare the cardiovascular response of this new training session to a traditional walking (TW) and 4 × 4 minutes Nordic walking session. This is a prospective observational study. Patients with Fontaine stage II PAD were included. Patients participated in Nordic walking sessions, which were randomly assigned as TW, 4 × 4 minute intervals, and peripheral artery disease adapted 30-20-10 exercise session (PAD-adapted 30-20-10 sessions). PAD-adapted 30-20-10 and 4 × 4 minutes sessions consisted of 4 repetitions of 4 minutes of effort followed by 3 minutes of passive recovery. PAD-adapted 30-20-10 session was characterized by 4 continuous 1-min repetitions at 3 different walking speeds [high (30 seconds), moderate (20 seconds) and low (10 seconds)]. During the 4 × 4 minutes session, patients were asked to cover the maximal distance at a constant speed. During TW session, patients were asked to walk at a speed inducing moderate-to-severe claudication pain. Heart rate, rating of perceived exertion (RPE) and claudication pain intensity using a visual analog scale were assessed. The perceived enjoyment of each session was assessed using a visual analog scale ranging from 0 (not enjoyable) to 10 (very enjoyable). Eleven patients with chronic symptomatic PAD were included (62 ±â€…13 years; 54% women). The mean heart rate during the time of effort was significantly higher in PAD-adapted 30-20-10 group than in 4 × 4 minutes and TW groups (127 ±â€…12, 122 ±â€…12, 114 ±â€…11 bpm, respectively; P ≤ .001). The mean rating of perceived exertion (16 ±â€…1, 15 ±â€…1, 13 ±â€…1; P ≤ .001) and claudication pain intensity (8 ±â€…1, 7 ±â€…1; 7 ±â€…1 mm; P ≤ .019) were significantly higher during PAD-adapted 30-20-10 sessions than during 4 × 4 minutes and TW sessions. The perceived enjoyment was similar among sessions (8.7 ±â€…1.6 for TW, 8.6 ±â€…1.7 for 4 × 4 minutes, and 8.8 ±â€…1.8 mm for PAD-adapted 30-20-10 sessions; P = .935). The PAD-adapted 30-20-10 session is feasible and induces higher cardiovascular stimulation and claudication pain than 4 × 4 minutes and TW procedures in patients with symptomatic PAD. Despite these different responses, a similar perceived enjoyment among the sessions has been shown. Future investigations are needed to examine the effects of this new training session in these patients.

Intravascular lithotripsy in peripheral lesions with severe calcification and its use in TAVI procedure - a meta-analysis.

Background: Heavily calcified peripheral artery lesions increase the risk of vascular complications, constituting a severe challenge for the operator during catheter-based cardiovascular interventions. Intravascular Lithotripsy (IVL) technology disrupts subendothelial calcification by using localized pulsative sonic pressure waves and represents a promising technique for plaque modification in patients with severe calcification in peripheral arteries. Purpose: Our aim was to systematically review and summarize available data regarding the safety and efficacy of IVL in preparing severely calcified peripheral arteries and its use in Transcatheter Aortic Valve Implantation (TAVI). Patients and methods: This study was conducted according to the PRISMA guidelines. We systematically searched PubMed, SCOPUS, and Cochrane databases from their inception to February 23, 2023, for studies assessing the characteristics and outcomes of patients undergoing IVL in the peripheral vasculature. The diameter of the vessel lumen before and after IVL was estimated. The occurrence of peri-procedural complications was assessed using a random-effects model. Results: 20 studies with a total of 1,223 patients with heavily calcified peripheral lesions were analysed. The mean age of the cohort was 70.6 ± 17.4 years. Successful IVL delivery achieved in 100% (95% CI: 100%-100%, I2 = 0%), with an increase in the luminal diameter (SMD: 4.66, 95% CI: 3.41-5.92, I2 = 90.8%) and reduction in diameter stenosis (SMD: -4.15, 95% CI: -4.75 to -3.55, I2 = 92.8%), and a concomitant low rate of complications. The procedure was free from dissection in 97% (95% CI: 91%-100%, I2 = 81.4%) while dissections of any type (A, B, C, or D) were observed in 6% (95% CI: 2%-10%, I2 = 85.3%) of the patients. Several rare cases of abrupt closure, no-reflow phenomenon, perforation, thrombus formation, and distal embolization were recorded. Finally, the subgroup analysis of patients who underwent a TAVI with IVL assistance presented successful implantation in 100% (95% CI: 100%-100%, I2 = 0%) of the cases, with only 4% (95% CI: 0%-12%, I2 = 68.96%) presenting dissections of any sort. Conclusions: IVL seems to be an effective and safe technique for modifying severely calcified lesions in peripheral arteries and it is a promising modality in TAVI settings. Future prospective studies are needed to validate our results.

A Novel Sirolimus-Coated Balloon for the Treatment of Femoropopliteal Lesions: The SELUTION SFA Japan Trial.

BACKGROUND: Sirolimus-coated balloons (SCB) for the treatment of femoropopliteal (FP) lesions have not been systematically studied, but initial outcomes from early studies are promising. OBJECTIVES: The authors sought to evaluate the safety and efficacy of the SELUTION SLR SCB, composed of proprietary microreservoir technology combining sirolimus and biodegradable polymer, when used to treat mild-to-moderate FP disease in a Japanese population. METHODS: This multicenter, prospective, single-arm study (SELUTION SFA JAPAN) enrolled 134 patients with FP disease. It was independently adjudicated by an imaging core laboratory and clinical events committee. The primary endpoint was 12-month primary patency, defined as peak systolic velocity ratio ≥2.5 by duplex ultrasound and compared against a prespecified performance goal of 60% based on established angioplasty data. RESULTS: The mean age was 73.8 ± 6.9 years, and 60.3% of patients had diabetes mellitus. The mean lesion length was 127.4 ± 59.7 mm, 17.2% were chronic total occlusions, and 47.8% involved the popliteal artery. Data on 12-month restenosis were available in 127 patients (94.8%). The 12-month primary patency rate was 87.9%, and the freedom from clinically driven target lesion revascularization (CD-TLR) was 97.0% per Kaplan-Meier estimate. The major adverse event rate was 6.7%, driven by 4 CD-TLRs and 5 deaths, none of which were related to the device or procedure. Ankle-brachial index data improved significantly from 0.73 ± 0.16 at baseline to 0.96 ± 0.14 at 30 days postprocedure and was sustained through 12 months (0.94 ± 0.13). CONCLUSIONS: The SELUTION SFA JAPAN trial demonstrated that a novel SELUTION SCB is a safe and effective treatment option for FP disease in symptomatic patients.

Relationship of apolipoprotein C-III proteoform composition with ankle-brachial index and peripheral artery disease in the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND AND AIMS: Apolipoprotein C-III (apoC-III) proteoform composition shows distinct relationships with plasma lipids and cardiovascular risk. The present study tested whether apoC-III proteoforms are associated with risk of peripheral artery disease (PAD). METHODS: ApoC-III proteoforms, i.e., native (C-III0a), and glycosylated with zero (C-III0b), one (C-III1) or two (C-III2) sialic acids, were measured by mass spectrometry immunoassay on 5,734 Multi-Ethnic Study of Atherosclerosis participants who were subsequently followed for clinical PAD over 17 years. Ankle-brachial index (ABI) was also assessed at baseline and then 3 and 10 years later in 4,830 participants. RESULTS: Higher baseline C-III0b/C-III1 and lower baseline C-III2/C-III1 were associated with slower decline in ABI (follow-up adjusted for baseline) over time, independently of cardiometabolic risk factors, and plasma triglycerides and HDL cholesterol levels (estimated difference per 1 SD was 0.31 % for both, p < 0.01). The associations between C-III2/C-III1 and changes in ABI were stronger in men (-1.21 % vs. -0.27 % in women), and in Black and Chinese participants (-0.83 % and -0.86 % vs. 0.12 % in White). Higher C-III0b/C-III1 was associated with a trend for lower risk of PAD (HR = 0.84 [95%CI: 0.67-1.04]) that became stronger after excluding participants on lipid-lowering medications (0.73 [95%CI: 0.57-0.94]). Neither change in ABI nor clinical PAD was related to total apoC-III levels. CONCLUSIONS: We found associations of apoC-III proteoform composition with changes in ABI that were independent of other risk factors, including plasma lipids. Our data further support unique properties of apoC-III proteoforms in modulating vascular health that go beyond total apoC-III levels.

The resistive and pulsatility indices of the dorsal metatarsal artery for the screening of peripheral lower artery disease in patients with and without diabetes.

BACKGROUND: In lower extremity peripheral artery disease (PAD), the ankle-brachial index (ABI) is an easily reproducible diagnostic tool for PAD, but it loses reliability when > 1.4 due to calcification of the vessel wall. Patients with diabetes are at higher risk for wall calcification. In order to overcome the limitation and reliability of ABI, particularly in patients with diabetes, we decided to assess resistive (RI) and pulsatility index (PI) by ultrasound doppler of the dorsal metatarsal artery (DMA). RESULTS: We therefore analyzed 51 legs (32 patients), evaluating the correlation between PI, RI, and ABI. Patients with diabetes were 21 (65.6 %), accounting for 33 legs (64.7 %). Out of 51 legs assessed, 37 (72.5 %) cases had compressible arteries, whereas in 14 legs (27.5 %) ABI was not calculable due to wall calcification. PAD was significantly associated with lower both RI and PI of the DMA (both p < 0.000). RI, but not PI, showed a significant correlation (r = 0.535) with ABI, when ABI was less than 1.4, but not when ABI > 1.4. When analyzed separately, patients with diabetes showed a similar figure in comparison with those without diabetes (r = 0.600), RI, but not PI, showed a significant correlation with ABI. CONCLUSION: Dorsal metatarsal artery resistive index (MARI) showed a significant inverse correlation with PAD, similarly to ABI, irrespective of the presence of diabetes. MARI seems to be an effective screening tool for PAD even in patients with wall calcification. Further studies are needed for confirming the results of the present pilot study.

Glycolytic PFKFB3 and Glycogenic UGP2 Axis Regulates Perfusion Recovery in Experimental Hind Limb Ischemia.

BACKGROUND: Despite being in an oxygen-rich environment, endothelial cells (ECs) use anaerobic glycolysis (Warburg effect) as the primary metabolic pathway for cellular energy needs. PFKFB (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase)-3 regulates a critical enzymatic checkpoint in glycolysis and has been shown to induce angiogenesis. This study builds on our efforts to determine the metabolic regulation of ischemic angiogenesis and perfusion recovery in the ischemic muscle. METHODS: Hypoxia serum starvation (HSS) was used as an in vitro peripheral artery disease (PAD) model, and hind limb ischemia by femoral artery ligation and resection was used as a preclinical PAD model. RESULTS: Despite increasing PFKFB3-dependent glycolysis, HSS significantly decreased the angiogenic capacity of ischemic ECs. Interestingly, inhibiting PFKFB3 significantly induced the angiogenic capacity of HSS-ECs. Since ischemia induced a significant in PFKFB3 levels in hind limb ischemia muscle versus nonischemic, we wanted to determine whether glucose bioavailability (rather than PFKFB3 expression) in the ischemic muscle is a limiting factor behind impaired angiogenesis. However, treating the ischemic muscle with intramuscular delivery of D-glucose or L-glucose (osmolar control) showed no significant differences in the perfusion recovery, indicating that glucose bioavailability is not a limiting factor to induce ischemic angiogenesis in experimental PAD. Unexpectedly, we found that shRNA-mediated PFKFB3 inhibition in the ischemic muscle resulted in an increased perfusion recovery and higher vascular density compared with control shRNA (consistent with the increased angiogenic capacity of PFKFB3 silenced HSS-ECs). Based on these data, we hypothesized that inhibiting HSS-induced PFKFB3 expression/levels in ischemic ECs activates alternative metabolic pathways that revascularize the ischemic muscle in experimental PAD. A comprehensive glucose metabolic gene qPCR arrays in PFKFB3 silenced HSS-ECs, and PFKFB3-knock-down ischemic muscle versus respective controls identified UGP2 (uridine diphosphate-glucose pyrophosphorylase 2), a regulator of protein glycosylation and glycogen synthesis, is induced upon PFKFB3 inhibition in vitro and in vivo. Antibody-mediated inhibition of UGP2 in the ischemic muscle significantly impaired perfusion recovery versus IgG control. Mechanistically, supplementing uridine diphosphate-glucose, a metabolite of UGP2 activity, significantly induced HSS-EC angiogenic capacity in vitro and enhanced perfusion recovery in vivo by increasing protein glycosylation (but not glycogen synthesis). CONCLUSIONS: Our data present that inhibition of maladaptive PFKFB3-driven glycolysis in HSS-ECs is necessary to promote the UGP2-uridine diphosphate-glucose axis that enhances ischemic angiogenesis and perfusion recovery in experimental PAD.