What Is the Best Experimental Model for Developing Novel Therapeutics in Peripheral Artery Disease?

CLINICAL PROBLEM: More than 200 million people worldwide have peripheral artery disease (PAD). PAD affects the quality of life and is associated with significant morbidity and mortality. Standard treatment for severe cases of PAD is surgical or endovascular revascularization. However, up to 30% of patients are not candidates for open or endovascular procedures, due to high operative risk or unfavorable vascular involvement. Furthermore, revascularization procedures may be insufficient to adequately improve microvascular tissue perfusion, wound healing, or limb salvage. Accordingly, regardless of advances in treatment modalities, outcomes of patients with PAD have remained unfavorable. Therefore, new medical therapeutic approaches are much needed. Small animal models are indispensable tools for the understanding of PAD physiopathology and the development of novel medical therapies. RECOMMENDATIONS FOR INCREASING TRANSLATION FROM ANIMAL MODELS: Development of animal models that more closely mimic the pathophysiology (with occlusive atherothrombosis and chronic development of limb ischemia) can incorporate the cardiovascular risk factors associated with this disease state, and focus on more clinically relevant outcomes is critical. In practice, this means using both animals that develop atherosclerosis and methods for the application of gradual arterial occlusion to induce hind limb ischemia. Doing so will likely help identify novel targets for intervention and overcome some principal challenges confronted by previous clinical trials. While various rodent models are discussed, the optimal animal model is yet to be defined.

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.

Arm and ankle blood pressure indices, and peripheral artery disease, and mortality: a cohort study.

BACKGROUND AND AIMS: Few studies have compared arm and ankle blood pressures (BPs) with regard to peripheral artery disease (PAD) and mortality. These relationships were assessed using data from three large prospective clinical trials. METHODS: Baseline BP indices included arm systolic BP (SBP), diastolic BP (DBP), pulse pressure (arm SBP minus DBP), ankle SBP, ankle-brachial index (ABI, ankle SBP divided by arm SBP), and ankle-pulse pressure difference (APPD, ankle SBP minus arm pulse pressure). These measurements were categorized into four groups using quartiles. The outcomes were PAD (the first occurrence of either peripheral revascularization or lower-limb amputation for vascular disease), the composite of PAD or death, and all-cause death. RESULTS: Among 40 747 participants without baseline PAD (age 65.6 years, men 68.3%, diabetes 50.2%) from 53 countries, 1071 (2.6%) developed PAD, and 4955 (12.2%) died during 5 years of follow-up. Incident PAD progressively rose with higher arm BP indices and fell with ankle BP indices. The strongest relationships were noted for ankle BP indices. Compared with people whose ankle BP indices were in the highest fourth, adjusted hazard ratios (95% confidence interval) for each lower fourth were 1.64 (1.31-2.04), 2.59 (2.10-3.20), and 4.23 (3.44-5.21) for ankle SBP; 1.19 (0.95-1.50), 1.66 (1.34-2.05), and 3.34 (2.75-4.06) for ABI; and 1.41 (1.11-1.78), 2.04 (1.64-2.54), and 3.63 (2.96-4.45) for APPD. Similar patterns were observed for mortality. Ankle BP indices provided the highest c-statistics and classification indices in predicting future PAD beyond established risk factors. CONCLUSIONS: Ankle BP indices including the ankle SBP and the APPD best predicted PAD and mortality.

Clinical physiology: the crucial role of MRI in evaluation of peripheral artery disease.

Peripheral artery disease (PAD) is a common vascular disease that primarily affects the lower limbs and is defined by the constriction or blockage of peripheral arteries and may involve microvascular dysfunction and tissue injury. Patients with diabetes have more prominent disease of microcirculation and develop peripheral neuropathy, autonomic dysfunction, and medial vascular calcification. Early and accurate diagnosis of PAD and disease characterization are essential for personalized management and therapy planning. Magnetic resonance imaging (MRI) provides excellent soft tissue contrast and multiplanar imaging capabilities and is useful as a noninvasive imaging tool in the comprehensive physiological assessment of PAD. This review provides an overview of the current state of the art of MRI in the evaluation and characterization of PAD, including an analysis of the many applicable MR imaging techniques, describing the advantages and disadvantages of each approach. We also present recent developments, future clinical applications, and future MRI directions in assessing PAD. The development of new MR imaging technologies and applications in preclinical models with translation to clinical research holds considerable potential for improving the understanding of the pathophysiology of PAD and clinical applications for improving diagnostic precision, risk stratification, and treatment outcomes in patients with PAD.

Effects of acute hyperoxia on autonomic function and coronary tone in patients with peripheral artery disease.

Numerous studies have shown that oxidative stress plays an important role in peripheral artery disease (PAD). Prior reports suggested autonomic dysfunction in PAD. We hypothesized that responses of the autonomic nervous system and coronary tone would be impaired in patients with PAD during exposure to acute hyperoxia, an oxidative stressor. In 20 patients with PAD and 16 healthy, sex- and age-matched controls, beat-by-beat heart rate (HR, from ECG) and blood pressure (BP, with Finometer) were recorded for 10 min during room air breathing and 5 min of hyperoxia. Cardiovagal baroreflex sensitivity and HR variability (HRV) were evaluated as measures of autonomic function. Transthoracic coronary echocardiography was used to assess peak coronary blood flow velocity (CBV) in the left anterior descending coronary artery. Cardiovagal baroreflex sensitivity at rest was lower in PAD than in healthy controls. Hyperoxia raised BP solely in the patients with PAD, with no change observed in healthy controls. Hyperoxia induced an increase in cardiac parasympathetic activity assessed by the high-frequency component of HRV in healthy controls but not in PAD. Indices of parasympathetic activity were lower in PAD than in healthy controls throughout the trial as well as during hyperoxia. Hyperoxia induced coronary vasoconstriction in both groups, while the coronary perfusion time fraction was lower in PAD than in healthy controls. These results suggest that the response in parasympathetic activity to hyperoxia (i.e., oxidative stress) is blunted and the coronary perfusion time is shorter in patients with PAD.NEW & NOTEWORTHY Patients with peripheral artery disease (PAD) showed consistently lower parasympathetic activity and blunted cardiovagal baroreflex sensitivity compared with healthy individuals. Notably, hyperoxia, which normally boosts parasympathetic activity in healthy individuals, failed to induce this response in patients with PAD. These data suggest altered autonomic responses during hyperoxia in PAD.

Sex differences in the purinergic 2 receptor-mediated blood pressure response to treadmill exercise in rats with simulated peripheral artery disease.

We investigated the role played by ATP-sensitive purinergic 2 (P2) receptors in evoking the pressor response to treadmill exercise in male and female rats with and without femoral arteries that were ligated for ∼72 h to induce simulated peripheral artery disease (PAD). We hypothesized that PPADS (P2 receptor antagonist, 10 mg iv) would reduce the pressor response to 4 min of treadmill exercise (15 m·min-1, 1° incline) and steady-state exercise plasma norepinephrine (NE) values in male and female rats, and that the magnitude of effect of PPADS would be greater in rats with simulated PAD ("ligated") than in sham-operated rats. In males, PPADS significantly reduced the difference between steady-state exercise and baseline mean arterial pressure (ΔMAP) response to treadmill exercise in sham (n = 8; pre-PPADS: 12 ± 2, post-PPADS: 1 ± 5 mmHg; P = 0.037) and ligated (n = 4; pre-PPADS: 20 ± 2, post-PPADS: 11 ± 3 mmHg; P = 0.028) rats with a similar magnitude of effect observed between groups (P = 0.720). In females, PPADS had no effect on the ΔMAP response to treadmill exercise in sham (n = 6; pre-PPADS: 9 ± 2, post-PPADS: 7 ± 2 mmHg; P = 0.448) or ligated (n = 6; pre-PPADS: 15 ± 2, post-PPADS: 16 ± 3 mmHg; P = 0.684) rats. When NE values were grouped by sex independent of ligation/sham status, PPADS significantly reduced plasma NE in male (P = 0.016) and female (P = 0.027) rats. The data indicate that P2 receptors contribute to the sympathetic response to exercise in both male and female rats but that the sympathoexcitatory role for P2 receptors translates into an obligatory role in the blood pressure response to exercise in male but not in female rats.NEW & NOTEWORTHY Here, we demonstrate that purinergic 2 (P2) receptors contribute significantly to the blood pressure response to treadmill exercise in male rats both with and without simulated PAD induced by femoral artery ligation. We found no role for P2 receptors in the blood pressure response to treadmill exercise in female rats, thus revealing clear sex differences in P2 receptor-mediated blood pressure control during exercise.

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.

High ankle-brachial index participants experienced similar long-term mortality as peripheral artery disease in a national sample of community-dwelling adults.

BACKGROUND: Only a few small studies have shown the association between high ankle-brachial pressure index (ABI >1.4) and adverse cardiovascular (CV) events and mortality. Although there is abundant literature depicting the association between ABI and overall systemic atherosclerosis, it typically focuses on low ABI. Furthermore, historically, many studies focusing on peripheral artery disease have excluded high ABI participants. We aimed to study the mortality outcomes of persons with high ABI in the National Health and Nutrition Examination Survey (NHANES). METHODS: We obtained ABI from participants aged ≥40 years for survey years 1999 to 2004. We defined low a ABI as ≤0.9, normal ABI as 0.9 to 1.4, and high ABI as >1.4 or if the ankle pressures were >245 mm Hg. Demographics, various comorbidities, and laboratory test results were obtained at the time of the survey interview. Multivariable adjusted hazard ratios (HRs) along with 95% confidence intervals (CIs) were calculated for CV and all-cause mortality via Cox proportional hazards regression. Mortality was linked to all NHANES participants for follow-up through December 31, 2019, by the Centers for Disease Control and Prevention. RESULTS: We identified 7639 NHANES participants with available ABI. Of these, 6787 (89%) had a normal ABI, 646 (8%) had a low ABI, and 206 (3%) had elevated ABI. Of participants with high ABI, 50% were men, 15% were African Americans, 10% were current smokers, 56% had hypertension, 33% had diabetes, 15% had chronic kidney disease (CKD), and 18% had concomitant coronary artery disease (CAD). Diabetes (odds ratio [OR], 2.4; 95% CI, 1.7-3.2), CAD (OR, 1.6; 95% CI, 1.0-2.4), and CKD (OR, 1.5; 95% CI, 1.0-2.3) at baseline were associated with having a high ABI, respectively. A high ABI was associated independently with elevated CV (HR, 2.6; 95% CI, 2.1-3.1; P < .0001) and all-cause mortality (HR, 2.5; 95% CI, 2.2-2.8; P < .0001) after adjusting for covariates, including diabetes, CKD, CAD, current smoking, cancer, and hypertension. CONCLUSIONS: A high ABI is associated with an elevated CV and all-cause mortality, similar to patients with PAD. High ABI participants should receive the same attention and aggressive medical therapies as patients with PAD.

Benefits of early vascular provider involvement in wound care center management of patients with underlying arterial disease.

OBJECTIVES: Peripheral arterial disease (PAD) can reduce wound healing rates by ≤30%. Current literature suggests wound outcomes are improved when management is driven by vascular providers. However, whether this benefit is derived solely from early vascular provider involvement remains unclear. METHODS: A retrospective analysis was performed of 80 limbs with chronic wounds and underlying PAD seen at our institution's wound center between July 2022 and July 2023. Arterial disease was defined by the following criteria: (1) prior PAD diagnosis, (2) ankle-brachial-index of <0.9 or toe pressure of <70 mm Hg, or (3) absent peripheral pulses. Patients were divided into early (<6 week) vascular provider exposure (EVE; n = 45) or late/no vascular exposure (LNVE; n = 35). Providers included vascular surgeons and affiliated advanced practitioners. The primary outcome studied was overall time to wound healing. Statistical analysis included χ2 tests, t test, Pearson correlation, Kaplan-Meier analysis, and Cox regression modeling (variables included in a multivariate model if univariate effect on healing was associated at P < .1). RESULTS: Baseline demographic profiles were similar between groups with exception of lower baseline albumin (P = .037), more heart failure (P = .013), and more prior peripheral endovascular interventions (P = .013) in the EVE group. Although the initial wound locations and sizes were similar, EVE wounds had significantly higher WIfI wound scores (1.9 ± 0.1 vs 1.6 ± 0.1; P = .039). Although more LNVE patients developed radiographic osteomyelitis (31.8% vs 55.6%; P = .033), fewer underwent operative debridement or amputation (100% vs 63.2%; P = .008). On univariate analysis, healing time tended to be shorter in EVE, but not significantly (P = .089). When controlled for comorbidities, however, healing rates were nearly two-fold higher in EVE (hazard ratio, 2.42; 95% confidence interval, 1.21-4.84). LNVE wounds also took significantly longer to reach checkpoints including time to >75% granulation (P = .05), 15% weekly size decrease (P = .044), and epithelialization (P = .026). LNVE patients required more wound center visits (P = .024) and procedures (P = .005) with a longer time to intervention (P = .041). All EVE patients obtained ankle-brachial indices, with 90.9% of them available at their first wound care visit (P < .001). Although a slightly greater proportion of patients underwent a major amputation in EVE (15.6% vs 11.4%; P = .595), this difference did not attain significance; additionally, 100% of EVE patients had documented discussion of nonsalvageable limbs before amputation. CONCLUSIONS: Early exposure to vascular practitioners improves wound healing time, timeliness to intervention, and wound center and hospital resource use in patients with PAD. Further investigation into benefits of vascular involvement within community wound center models could significantly improve awareness and accessibility of arterial wound care in smaller/remote communities.

Comparative evaluation of transcutaneous oxygen tension and ankle-brachial index as predictors of reoperation following below-knee amputation.

OBJECTIVE: Decision-making regarding level of lower extremity amputation is sometimes challenging. Selecting an appropriate anatomic level for major amputation requires consideration of tradeoffs between postoperative function and risk of wound complications that may require additional operations, including debridement and/or conversion to above-knee amputation (AKA). We evaluated the utility of common, non-invasive diagnostic tests used in clinical practice to predict the need for reoperations among patients undergoing primary, elective, below knee-amputations (BKAs) by vascular surgeons. METHODS: Patients undergoing elective BKA over a 5-year period were identified using Current Procedural Terminology codes. Medical records were reviewed to characterize demographics, pre-amputation testing transcutaneous oxygen tension (TcPO2), and ankle-brachial index (ABI). The need for ipsilateral post-BKA reoperation (including BKA revision and/or conversion to AKA) regardless of indication was the primary outcome. Associations were evaluated using univariable and multivariable logistic regression models. Cutpoints for TcPO2 values associated with amputation reoperation were evaluated using receiver operating characteristic curves. RESULTS: We identified 175 BKAs, of which 46 (26.3%) required ipsilateral reoperation (18.9% BKA revisions and 14.3% conversions to AKA). The mean age was 63.3 ± 14.8 years. Most patients were male (65.1%) and White (72.0%). Mean pre-amputation calf TcPO2 was 40.0 ± 20.5 mmHg, and mean ABI was 0.64 ± 0.45. In univariable models, post-BKA reoperation was associated with calf TcPO2 (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.94-0.99; P = .013) but not ABI (OR, 0.53; 95% CI, 0.19-1.46; P = .217). Univariable associations with reoperation were also identified for age (OR, 0.97; 95% CI, 0.94-0.990; P = .003) and diabetes (OR, 0.43; 95% CI, 0.21-0.87; P = .019). No associations with amputation revision were identified for gender, race, end-stage renal disease, or preoperative antibiotics. Calf TcPO2 remained associated with post-BKA reoperation in a multivariable model (OR, 0.97; 95% CI, 0.94-0.99; P = .022) adjusted for age (OR, 0.98; 95% CI, 0.94-1.01; P = .222) and diabetes (OR, 0.98; 95% CI, 0.94-1.01; P = .559). Receiver operating characteristic analysis suggested a TcPO2 ≥38 mmHg as an appropriate cut-point for assessing risk for BKA revision (area under the curve = 0.682; negative predictive value, 0.91). CONCLUSIONS: Reoperation after BKA is common, and reoperation risk was associated with pre-amputation TcPO2. For patients undergoing elective BKA, higher risk of reoperation should be discussed with patients with an ipsilateral TcPO2 <38 mmHg.

Long-term patient-reported outcomes among patients undergoing revascularization vs medical therapy for intermittent claudication.

OBJECTIVE: Society for Vascular Surgery guidelines recommend revascularization for patients with intermittent claudication (IC) if it can improve patient function and quality of life. However, it is still unclear if patients with IC achieve a significant functional benefit from surgery compared with medical management alone. This study examines the relationship between IC treatment modality (operative vs nonoperative optimal medical management) and patient-reported outcomes for physical function (PROMIS-PF) and satisfaction in social roles and activities (PROMIS-SA). METHODS: We identified patients with IC who presented for index evaluation in a vascular surgery clinic at an academic medical center between 2016 and 2021. Patients were stratified based on whether they underwent a revascularization procedure during follow-up vs continued nonoperative management with medication and recommended exercise therapy. We used linear mixed-effect models to assess the relationship between treatment modality and PROMIS-PF, PROMIS-SA, and ankle-brachial index (ABI) over time, clustering among repeat patient observations. Models were adjusted for age, sex, diabetes, Charlson Comorbidity Index, Clinical Frailty Score, tobacco use, and index ABI. RESULTS: A total of 225 patients with IC were identified, of which 40% (n = 89) underwent revascularization procedures (42% bypass; 58% peripheral vascular intervention) and 60% (n = 136) continued nonoperative management. Patients were followed up to 6.9 years, with an average follow-up of 5.2 ± 1.6 years. Patients who underwent revascularization were more likely to be clinically frail (P = .03), have a lower index ABI (0.55 ± 0.24 vs 0.72 ± 0.28; P < .001), and lower baseline PROMIS-PF score (36.72 ± 8.2 vs 40.40 ± 6.73; P = .01). There were no differences in patient demographics or medications between treatment groups. Examining patient-reported outcome trends over time; there were no significant differences in PROMIS-PF between groups, trends over time, or group differences over time after adjusting for covariates (P = .07, P = .13, and P =.08, respectively). However, all patients with IC significantly increased their PROMIS-SA over time (adjusted P = .019), with patients managed nonoperatively more likely to have an improvement in PROMIS-SA over time than those who underwent revascularization (adjusted P = .045). CONCLUSIONS: Patient-reported outcomes associated with functional status and satisfaction in activities are similar for patients with IC for up to 7 years, irrespective of whether they undergo treatment with revascularization or continue nonoperative management. These findings support conservative long-term management for patients with IC.

The natural history of isolated common femoral endarterectomy for chronic limb-threatening ischemia.

OBJECTIVE: Occlusive disease of the common femoral artery can generate profound lower extremity ischemia as the normal collateral pathways from the profunda to the superficial femoral artery cannot adequately develop. In patients with lifestyle-limiting claudication, isolated common femoral endarterectomy (CFE) is highly effective. Because CFE does not provide direct, in-line flow to the plantar arch, it has been felt to provide inadequate revascularization to patients with chronic limb-threatening ischemia (CLTI). The purpose of this retrospective clinical study was to report and assess the natural history of selected patients with CLTI treated with isolated CFE (without concomitant infrainguinal revascularization). METHODS: Consecutive CFEs performed in a large, urban hospital for CLTI between 2014 and 2021 were reviewed. Patient characteristics, limb, and anatomical stages using the Wound, Ischemia, foot Infection (WIfI) and Global Limb Anatomic Staging System were tabulated. Limb-specific and survival-related end points were analyzed. RESULTS: Fifty-eight patients presenting with CLTI underwent isolated CFE (mean age, 74 ± 10 years; 62% male, 90% current or prior smoker). Comorbidities included diabetes (52%), coronary artery disease (55%), congestive heart failure (22%), and end-stage renal failure on hemodialysis (5%). Patients presented with either rest pain (36%) or tissue loss (64%); the latter group exhibited advanced limb threat (68% in WIfI stage 3 or 4). The majority of patients had associated severe infrainguinal disease (50% Global Limb Anatomic Staging Systems 3). After a median follow-up of 17 months (range, 10-29 months), vascular reintervention was required in 7 patients (12%). One patient (2%) required major limb amputation after presentation in WIfI stage 4 (W3I3fI0). Indeed, WIfI stage 4 was a significant univariate predictor of the need for subsequent infrainguinal bypass (P = .034). CONCLUSIONS: Isolated CFE as primary therapy in highly selected patients with CLTI was safe and effective. Index limb stage is predictive of the need for associated infrainguinal revascularization in this complex population.

Comparison of outcomes of percutaneous deep venous arterialization in multiple practice settings.

OBJECTIVE: We compared the efficacy of percutaneous deep venous arterialization (pDVA) in patients with no-option chronic limb-threatening ischemia in the hospital vs in office-based laboratory (OBL) settings. METHODS: A retrospective chart review was performed of all patients who underwent pDVA using off-the-shelf devices from January 2018 to March 2023 in a hospital and an OBL. We identified 73 eligible patients, 41 from a hospital setting (59% male; median age, 72 years; interquartile range, 18 years) and 32 from an OBL setting (59% males; 67 years; interquartile range, 16 years). All eligible patients were deemed to have no-option critical limb ischemia, had at least one patent proximal tibial artery available for the creation of an arteriovenous anastomosis, and were classified as having Rutherford classification IV or higher peripheral arterial disease. Patients were ineligible if classified as Rutherford classification III or lower, had active infection, did not have at least one appropriate venous target, and/or had rapidly progressing wounds requiring immediate major amputation. The primary outcome was major amputation-free survival (AFS). Secondary outcomes included technical success, limb salvage, survival, primary patency, reintervention rate, adverse events, and partial and complete wound healing. Outcomes were evaluated using Kaplan-Meier method, log-rank, and two-stage procedure tests. RESULTS: Technical success was achieved in 70 patients (96%) with 1 hospital (2.4%) and 2 OBL (6.3%) patients lost to follow-up. Major AFS estimates at 6 months, 1 year, and 2 years were 51.4%, 40.4%, and 30.2% in the hospital group and 69.4%, 54.0%, and 49.5% in the OBL group, respectively. Partial wound healing estimates at 6 months, 1 year, and 2 years were 27.5%, 71.7%, and 81.2% in the hospital group and 62.7% at all time points in the OBL group. Complete wound healing estimates at 6 months, 1 year, and 2 years were 6.7%, 33.3%, and 33.3% in the hospital group and 5.3%, 37.7%, and 41.6% in the OBL group, respectively. There was no significant difference in major AFS (P = .13), limb salvage (P = .07), survival (P = .69), primary patency (P = .53), partial (P = .08), or complete wound healing (P = .79) between groups. Reintervention was performed in 8 hospital (20.5%) and 14 OBL (45.2%) patients. CONCLUSIONS: pDVA is a feasible and safe procedure for no-option critical limb ischemia in the hospital and OBL setting without significant differences in outcomes at ≤2 years.

Impact of early intervention on health status outcomes in peripheral artery disease patients with chronic total occlusion lesions using the PORTRAIT registry.

OBJECTIVE: To analyze the impact of noninvasive and early invasive treatments on health status in patients with lower extremity peripheral arterial disease (PAD) without and with chronic total occlusions (CTOs) after 12 months of follow-up. METHODS: Using the international (the United States, the Netherlands, and Australia) observational longitudinal Patient-Centered Outcomes Related to Treatment Practices in Peripheral Arterial Disease: Investigating Trajectories registry, we included patients with recent PAD symptoms between June 2011 and December 2015. We assessed the PAD-specific health status at initial visit and the 3-, 6-, and 12-month follow-up using the Peripheral Arterial Questionnaire. On a propensity matched-weighted cohort, we compared patients' characteristics by CTO status and treatment groups as early invasive (revascularization in the 3 months) vs noninvasive (exercise, medical therapies, or smoking cessation). We then assessed the health status trajectory over 12 months, as a three-way interaction between CTO status, treatment groups, and months, using a multilevel generalized linear regression model for repeated measures adjusted for baseline health status with random effects at the site and patient levels. RESULTS: We included 581 participants, with a mean age of 66.62 ± 9.33 years, 34.3% female, and 90.8% White, of whom 353 (60.8%) were without and 228 (39.2%) had a CTO lesion. Respectively, 96 (27.2%) and 70 (30.7%) patients underwent early invasive treatment (d = 0.07). Although patients with CTO were more likely to have lower resting ABI, multilevel disease, and to experience severe claudication vs their counterparts (|d| ≥ 0.20), patient health status at baseline with CTO was not different from those without CTO, with mean summary scores of 45.14 ± 20.26 vs 45.90 ± 21.24 (d = 0.04), respectively. The trajectory did not differ by CTO status (interaction CTO status × month; P = .517) and was higher in early invasive vs noninvasive treatment (treatment × month; P < .001), regardless of CTO status (CTO status × treatment; P = .981 and CTO status × treatment × month; P = .264). The score increased over time with the largest improvement occurring at 3 months in both noninvasive (non-CTO, +7.82 [95% confidence interval (CI), 4.03-11.60] and CTO, +9.27 95% CI, 4.45-14.09) and early invasive (non-CTO, +26.17 [95% CI, 20.06-32.28] and CTO, +24.52 [95% CI, 17.40-31.64] groups. The mean score in CTO vs non-CTO groups did not differ at each timepoint, with a 12-month mean score of 70.26 (95% CI, 67.87-74.65) vs 71.17 (95% CI, 65.91-76.44) (P = .99) in the noninvasive treatment and 84.93 (95% CI, 78.90-90.97) vs 79.20 (95% CI, 72.77-86.14) (P = .31) in the early invasive treatment. CONCLUSIONS: Patients with symptomatic PAD undergoing early revascularization exhibited better health status over time vs those undergoing noninvasive treatment strategy, irrespective of the presence of CTOs. The degree of the improvement was greater in the 3 months after the initial visit, especially in patients undergoing early revascularization.

Incentives and individualized coaching improve completion rates of supervised exercise therapy for claudication.

OBJECTIVE: Supervised exercise therapy (SET) provides clinical benefit for patients suffering from intermittent claudication and has been widely recommended as first-line therapy before endovascular or surgical intervention. However, published rates of SET program completion range from 5% to 55%, with historic completion of 54% at our own institution. As such, we sought to identify if targeted patient-supportive interventions improve SET completion rates while still maintaining efficacious SET programming. METHODS: Patients who were diagnosed with intermittent claudication, as defined by ankle-brachial index (ABI) <0.9 without rest pain, were offered enrollment in a prospective quality improvement protocol for our 12-week SET for peripheral artery disease program. Program completion was defined as ≥24 of 36 offered sessions over 12 weeks. A three-pronged approach was utilized to improve completion during the study, including financial incentives up to $180, scheduled coaching with our advanced practitioner staff, and informational materials on the importance of SET programming and lifestyle modification. Patient-reported improvements in walking symptoms were tracked via regularly administered questionnaires. Functional measures of SET programming including total walking duration and distance, metabolic equivalent of task, and ABIs; vascular intervention within 12-months after enrollment was also collected and compared using univariate paired analysis. RESULTS: In total, seventy-three patients were enrolled in SET for peripheral artery disease programming over the study period. Utilizing our three-pronged coaching approach, 56 patients completed SET programming, increasing our SET completion rate to 76.7% over a 2-year study period. Compared with pre-SET baseline, patients who completed SET noted less pain, aching, cramps in calves when walking (P = .004), and less difficulty walking 1 block (P = .038). Additionally, patients significantly increased their metabolic equivalent of task (3.1 vs 2.6; P < .001), total walking duration (30 mins vs 13.5 mins; P < .001), and total walking distance (0.7 vs 0.3 miles; P < .001) from their pre-SET baseline. There were no changes in participant ABIs from enrollment to completion in participants. Patients who completed SET programming also delayed vascular intervention compared with those who did not complete SET or declined participation (213.5 vs 122.5 days from enrollment; P = .041). CONCLUSIONS: Targeted incentives, including cost-coverage vouchers and personalized coaching with instructional materials, successfully improved patient completion of a prescribed SET program. Patients who completed SET programming reported subjective improvement in walking symptoms and objective walking benefits. In addition, these patients had delayed time to vascular intervention, supporting current vascular guidelines advocating for effective SET therapy prior to offering vascular intervention for intermittent claudication.

Single-center experience with the JETi Hydrodynamic Thrombectomy System for acute limb ischemia.

OBJECTIVE: Acute limb ischemia (ALI) remains a vascular emergency with high morbidity and mortality. While the JETi Hydrodynamic Thrombectomy System (Abbott) offers a percutaneous approach to fragment and aspirate the thrombus in patients with arterial occlusions, data on its efficacy and safety are limited. This study reports our early experience using the JETi device to treat ALI at our institution. METHODS: This is a single-center, retrospective review of patients with ALI treated with the JETi device between September 2020 and December 2022. Patients were included if the JETi device was used either as a primary intervention or as an adjunct procedure. The primary endpoint was technical success defined as <50% residual thrombus after intervention. Secondary endpoints included achieving complete resolution of the thrombus on angiogram, acute kidney injury (AKI), major bleeding, 30-day major amputation, and 30-day mortality. RESULTS: A total of 59 JETi procedures for ALI (median age 62 years [interquartile range: 56-71 years]) were performed on 39 male and 20 female patients. The median time from onset of symptoms to hospitalization was 24 hours (interquartile range: 4-168 hours). Rutherford classifications were I (10), IIa (27), IIb (14), and undocumented (8). Etiology of ALI was native vessel thrombosis (27), embolism (16), graft/stent thrombosis (14), and iatrogenic (2). A total of 124 vessels were treated, with an average of 2.1 vessels per procedure. The primary outcome was achieved in 86% (107/124) of the arteries, with 82% (102/124) successfully opened using the JETi device alone without the need for any adjunctive therapy. Complete resolution of the thrombus using JETi was achieved in 81% (101/124) arteries, with or without the use of adjunctive therapy. A total of 6.7% (4/59) patients required a major limb amputation within 30 days despite successful recanalization, and one 30-day mortality was recorded. Complications included distal embolization (5), access site hematoma (2), and AKI (4). No major bleeding, hemolysis-induced AKI, or vessel dissection or perforation was observed. CONCLUSIONS: The JETi device appears to be a safe and effective percutaneous treatment option in the management of ALI. It provides definitive treatment with a high technical success rate of 86% and a good safety profile.

Comparative outcomes of arterial bypass using the human acellular vessel and great saphenous vein in patients with chronic limb ischemia.

OBJECTIVE: The Human Acellular Vessel (HAV) is a novel, off-the-shelf biologic conduit being evaluated for arterial reconstructions. Regulatory studies in peripheral arterial disease (PAD) to date have consisted of single-arm cohorts with no comparator groups to contrast performance against established standards. This study aimed to compare outcomes of the HAV with autologous great saphenous vein (GSV) in patients with advanced PAD undergoing infrageniculate bypass. METHODS: Patients with advanced PAD and no autologous conduit who underwent bypass with the 6-mm diameter HAV (Group 1; n = 34) (March 2021-February 2024) were compared with a multicenter historical cohort who had bypass with single-segment GSV (group 2; n = 88) (January 2017-December 2022). The HAV was used under an Investigational New Drug protocol issued by the Food and Drug Administration (FDA) under the agency's Expanded Access Program. RESULTS: Demographics were comparable between groups (mean age 69 ± 10 years; 71% male). Group 1 had higher rates of tobacco use (37 pack-years vs 28 pack-years; P = .059), coronary artery disease (71% vs 43%; P = .007), and prior coronary artery bypass grafting (38% vs 14%; P = .003). Group 1 had more patients classified as wound, ischemia, and foot infection clinical stage 4 (56% vs 33%; P = .018) and with previous index leg revascularizations (97% vs 53%; P < .001). Both groups had a similar number of patients with chronic limb-threatening ischemia (Rutherford class 4-6) (88% vs 86%; P = .693) and Global Anatomic Staging System stage III (91% vs 96%; P = .346). Group 1 required a composite conduit (two HAV sewn together) in 85% of bypasses. The tibial vessels were the target in 79% of group 1 and 100% of group 2 (P < .001). Group 1 had a lower mean operative time (364 minutes vs 464 minutes; P < .001). At a median of 12 months, major amputation-free survival (73% vs 81%; P = .55) and overall survival (84% vs 88%; P = .20) were comparable. Group 1 had lower rates of primary patency (36% vs 50%; P = .044), primary-assisted patency (45% vs 72%; P = .002), and secondary patency (64% vs 72%; P = .003) compared with group 2. CONCLUSIONS: Implanted under Food and Drug Administration Expanded Access provisions, the HAV was more likely to be used in redo operations and cases with more advanced limb ischemia than GSV. Despite modest primary patency, the HAV demonstrated resilience in a complex cohort with no autologous conduit options, achieving good secondary patency and providing major amputation-free survival comparable with GSV at 12 months.

One-year limb salvage and quality of life following mechanical aspiration thrombectomy in patients with acute lower extremity ischemia.

OBJECTIVE: Lower extremity acute limb ischemia (LE-ALI) is associated with high morbidity and mortality rates, and a burden on patient quality of life (QoL). There is limited medium- to long-term evidence on mechanical aspiration thrombectomy (MT) in patients with LE-ALI. The STRIDE study was designed to assess safety and efficacy of MT using the Indigo Aspiration System in patients with LE-ALI. Thirty-day primary and secondary endpoints and additional outcomes were previously published. Here, we report 365-day secondary endpoints and QoL data from STRIDE. METHODS: STRIDE was a multicenter, prospective, single-arm, observational cohort study that enrolled 119 patients across 16 sites in the United States and Europe. Patients were treated first-line with MT using the Indigo Aspiration System (Penumbra, Inc). The study completed follow-up in October 2023. Secondary endpoints at 365 days included target limb salvage and mortality. Additionally, the VascuQoL-6 questionnaire, developed for evaluating patient-centered QoL outcomes for peripheral arterial disease, was assessed at baseline and follow-up through 365 days. RESULTS: Seventy-three percent of patients (87/119) were available for 365-day follow-up. Mean age of these patients was 65.0 ± 13.3 years, and 44.8% were female. Baseline ischemic severity was classified as Rutherford I in 12.6%, Rutherford IIa in 51.7%, and Rutherford IIb in 35.6%. In general, baseline and disease characteristics (demographics, medical history, comorbidities, target thrombus) of these patients are similar to the enrolled cohort of 119 patients. The secondary endpoints at 365 days for target limb salvage was 88.5% (77/87) and mortality rate was 12.0% (12/100). VascuQoL-6 improved across all domains, with a median total score improvement from 12.0 (interquartile range, 9.0-15.0) at baseline to 19.0 (interquartile range, 16.0-22.0) at 365 days. CONCLUSIONS: These 365-day results from STRIDE demonstrate that first-line MT with the Indigo Aspiration System for LE-ALI portray continued high target limb salvage rates and improved patient-reported QoL. These findings indicate Indigo as a safe and effective therapeutic option for LE-ALI.

Contemporary outcomes for arterial reconstruction with non-saphenous vein cryo-preserved conduits.

OBJECTIVE: Cryopreserved (CP) products are utilized during challenging cases when autogenous or prosthetic conduit use is not feasible. Despite decades of experience with cadaveric greater saphenous vein (GSV), there is limited available data regarding the outcomes and patency of other CP products, specifically arterial and deep venous grafts. This study was designed to evaluate outcomes of non-GSV CP conduits in patients undergoing urgent, emergent, and elective arterial reconstruction at our institution. We hypothesized that non-GSV CP allografts have adequate patency and outcomes and are therefore a feasible alternative to GSV in settings where autologous graft is unavailable or prosthetic grafts are contraindicated. METHODS: This study was approved by the Institutional Review Board at our institution. We retrospectively reviewed charts of patients undergoing arterial reconstructions using CP conduits from 2010 to 2022. Data collected included demographics, comorbidities, smoking status, indications for surgery, indication for CP conduit use, anatomic reconstruction, urgency of procedure, and blood loss. Time-to-event outcomes included primary and secondary graft patency rates, follow-up amputations, and mortality; other complications included follow-up infection/reinfection and 30-day complications, including return to the operating room and perioperative mortality. Time-to-event analyses were evaluated using product-limit survival estimates. RESULTS: Of 96 identified patients receiving CP conduits, 56 patients received non-GSV conduits for 66 arterial reconstructions. The most common type of non-GSV CP product used was femoral artery (31 patients), followed by aorto-iliac artery (22 patients), and femoral vein (19 patients), with some patients receiving more than one reconstruction or CP product. Patients were mostly male (75%), with a mean age of 63.1 years and a mean body mass index of 26.7 kg/m2. Indications for CP conduit use included infection in 53 patients, hostile environment in 36 patients, contaminated field in 30 patients, tissue coverage concerns in 30 patients, inadequate conduit in nine patients, and patient preference in one patient. Notably, multiple patients had more than one indication. Most surgeries (95%) were performed in urgent or emergent settings. Supra-inguinal reconstructions were most common (53%), followed by extra-anatomic bypasses (47%). Thirty-day mortality occurred in 10 patients (19%). Fifteen patients (27%) required return to the operating room for indications related to the vascular reconstructions, with 10 (18%) cases being unplanned and five (9%) cases planned/staged. Overall survival at 6, 12, and 24 months was 80%, 68%, and 59%, respectively. Primary patency at 6, 12, and 24 months was 86%, 70%, and 62%, respectively. Amputation freedom at 6 months, 12 months, and 24 months was 98%, 95%, and 86%, respectively for non-traumatic indications. CONCLUSIONS: Non-GSV CP products may be used in complex arterial reconstructions when autogenous or prosthetic options are not feasible or available.

Predictors of amputation-free survival and wound healing after infrainguinal bypass with alternative conduits.

OBJECTIVE: Inadequate vein quality or prior harvest precludes use of autologous single segment greater saphenous vein (ssGSV) in many patients with chronic limb-threatening ischemia (CLTI). Predictors of patient outcome after infrainguinal bypass with alternative (non-ssGSV) conduits are not well-understood. We explored whether limb presentation, bypass target, and conduit type were associated with amputation-free survival (AFS) after infrainguinal bypass using alternative conduits. METHODS: A single-center retrospective study (2013-2020) was conducted of 139 infrainguinal bypasses performed for CLTI with cryopreserved ssGSV (cryovein) (n = 71), polytetrafluoroethylene (PTFE) (n = 23), or arm/spliced vein grafts (n = 45). Characteristics, Wound, Ischemia, and foot Infection (WIfI) stage, and outcomes were recorded. Multivariable Cox proportional hazards and classification and regression tree analysis modeled predictors of AFS. RESULTS: Within 139 cases, the mean age was 71 years, 59% of patients were male, and 51% of cases were nonelective. More patients undergoing bypass with cryovein were WIfI stage 4 (41%) compared with PTFE (13%) or arm/spliced vein (27%) (P = .04). Across groups, AFS at 2 years was 78% for spliced/arm, 79% for PTFE, and 53% for cryovein (adjusted hazard ratio for cryovein, 2.5; P = .02). Among cases using cryovein, classification and regression tree analysis showed that WIfI stage 3 or 4, age >70 years, and prior failed bypass were predictive of the lowest AFS at 2 years of 36% vs AFS of 58% to 76% among subgroups with less than two of these factors. Although secondary patency at 2 years was worse in the cryovein group (26% vs 68% and 89% in arm/spliced and PTFE groups; P < .01), in patients with tissue loss there was no statistically significant difference in wound healing in the cryovein group (72%) compared with other bypass types (72% vs 87%, respectively; P = .12). CONCLUSIONS: In patients with CLTI lacking suitable ssGSV, bypass with autogenous arm/spliced vein or PTFE has superior AFS compared with cryovein, although data were limited for PTFE conduits for distal targets. Despite poor patency with cryovein, wound healing is achieved in a majority of cases, although it should be used with caution in older patients with high WIfI stage and prior failed bypass, given the low rates of AFS.