Mitochondrial fatty acid beta-oxidation: a possible therapeutic target for skeletal muscle lipotoxicity in peripheral artery disease myopathy.

Peripheral artery disease (PAD) is an atherosclerotic disease impacting over 200 million individuals and the prevalence increases with age. PAD occurs when plaque builds up within the peripheral arteries, leading to reduced blood flow and oxygen supply to the outer extremities. Individuals who experience PAD suffer from ischemia, which is typically accompanied by significant damage to skeletal muscles. Additionally, this tissue damage affects mitochondria, causing them to become dysregulated and dysfunctional, resulting in decreased metabolic rates. As there is no known cure for PAD, researchers are exploring potential therapeutic targets by examining coexisting cardiovascular conditions and metabolic risk factors, such as the aging process. Among these comorbidities, type-two diabetes mellitus and obesity are particularly common in PAD cases. These conditions, along with aging itself, are associated with an elevated accumulation of ectopic lipids within skeletal muscles, similar to what is observed in PAD. Researchers have attempted to reduce excess lipid accumulation by increasing the rate of fatty acid beta oxidation. Manipulating acetyl coenzyme A carboxylase 2, a key regulatory protein of fatty acid beta oxidation, has been the primary focus of such research. When acetyl coenzyme A carboxylase 2 is inhibited, it interrupts the conversion of acetyl-CoA into malonyl-CoA, resulting in an increase in the rate of fatty acid beta oxidation. By utilizing samples from PAD patients and applying the pharmacological strategies developed for acetyl coenzyme A carboxylase 2 in diabetes and obesity to PAD, a potential new therapeutic avenue may emerge, offering hope for improved quality of life for individuals suffering from PAD.

Oxidative damage in the gastrocnemius predicts long-term survival in patients with peripheral artery disease.

Patients with peripheral artery disease (PAD) have increased mortality rates and a myopathy in their affected legs which is characterized by increased oxidative damage, reduced antioxidant enzymatic activity and defective mitochondrial bioenergetics. This study evaluated the hypothesis that increased levels of oxidative damage in gastrocnemius biopsies from patients with PAD predict long-term mortality rates. Oxidative damage was quantified as carbonyl adducts in myofibers of the gastrocnemius of PAD patients. The oxidative stress data were grouped into tertiles and the 5-year, all-cause mortality for each tertile was determined by Kaplan-Meier curves and compared by the Modified Peto test. A Cox-regression model was used to control the effects of clinical characteristics. Results were adjusted for age, sex, race, body mass index, ankle-brachial index, smoking, physical activity, and comorbidities. Of the 240 study participants, 99 died during a mean follow up of 37.8 months. Patients in the highest tertile of oxidative damage demonstrated the highest 5-year mortality rate. The mortality hazard ratios (HR) from the Cox analysis were statistically significant for oxidative damage (lowest vs middle tertile; HR = 6.33; p = 0.0001 and lowest vs highest; HR = 8.37; p < 0.0001). Survival analysis of a contemporaneous population of PAD patients identifies abundance of carbonyl adducts in myofibers of their gastrocnemius as a predictor of mortality rate independently of ankle-brachial index, disease stage and other clinical and myopathy-related covariates.

Diet-induced obesity augments ischemic myopathy and functional decline in a murine model of peripheral artery disease.

Peripheral artery disease (PAD) causes an ischemic myopathy contributing to patient disability and mortality. Most preclinical models to date use young, healthy rodents with limited translatability to human disease. Although PAD incidence increases with age, and obesity is a common comorbidity, the pathophysiologic association between these risk factors and PAD myopathy is unknown. Using our murine model of PAD, we sought to elucidate the combined effect of age, diet-induced obesity and chronic hindlimb ischemia (HLI) on (1) mobility, (2) muscle contractility, and markers of muscle (3) mitochondrial content and function, (4) oxidative stress and inflammation, (5) proteolysis, and (6) cytoskeletal damage and fibrosis. Following 16-weeks of high-fat, high-sucrose, or low-fat, low-sucrose feeding, HLI was induced in 18-month-old C57BL/6J mice via the surgical ligation of the left femoral artery at 2 locations. Animals were euthanized 4-weeks post-ligation. Results indicate mice with and without obesity shared certain myopathic changes in response to chronic HLI, including impaired muscle contractility, altered mitochondrial electron transport chain complex content and function, and compromised antioxidant defense mechanisms. However, the extent of mitochondrial dysfunction and oxidative stress was significantly greater in obese ischemic muscle compared to non-obese ischemic muscle. Moreover, functional impediments, such as delayed post-surgical recovery of limb function and reduced 6-minute walking distance, as well as accelerated intramuscular protein breakdown, inflammation, cytoskeletal damage, and fibrosis were only evident in mice with obesity. As these features are consistent with human PAD myopathy, our model could be a valuable tool to test new therapeutics.

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.

Factors associated with successful median arcuate ligament release in an international, multi-institutional cohort.

OBJECTIVE: Prior research on median arcuate ligament syndrome has been limited to institutional case series, making the optimal approach to median arcuate ligament release (MALR) and resulting outcomes unclear. In the present study, we compared the outcomes of different approaches to MALR and determined the predictors of long-term treatment failure. METHODS: The Vascular Low Frequency Disease Consortium is an international, multi-institutional research consortium. Data on open, laparoscopic, and robotic MALR performed from 2000 to 2020 were gathered. The primary outcome was treatment failure, defined as no improvement in median arcuate ligament syndrome symptoms after MALR or symptom recurrence between MALR and the last clinical follow-up. RESULTS: For 516 patients treated at 24 institutions, open, laparoscopic, and robotic MALR had been performed in 227 (44.0%), 235 (45.5%), and 54 (10.5%) patients, respectively. Perioperative complications (ileus, cardiac, and wound complications; readmissions; unplanned procedures) occurred in 19.2% (open, 30.0%; laparoscopic, 8.9%; robotic, 18.5%; P < .001). The median follow-up was 1.59 years (interquartile range, 0.38-4.35 years). For the 488 patients with follow-up data available, 287 (58.8%) had had full relief, 119 (24.4%) had had partial relief, and 82 (16.8%) had derived no benefit from MALR. The 1- and 3-year freedom from treatment failure for the overall cohort was 63.8% (95% confidence interval [CI], 59.0%-68.3%) and 51.9% (95% CI, 46.1%-57.3%), respectively. The factors associated with an increased hazard of treatment failure on multivariable analysis included robotic MALR (hazard ratio [HR], 1.73; 95% CI, 1.16-2.59; P = .007), a history of gastroparesis (HR, 1.83; 95% CI, 1.09-3.09; P = .023), abdominal cancer (HR, 10.3; 95% CI, 3.06-34.6; P < .001), dysphagia and/or odynophagia (HR, 2.44; 95% CI, 1.27-4.69; P = .008), no relief from a celiac plexus block (HR, 2.18; 95% CI, 1.00-4.72; P = .049), and an increasing number of preoperative pain locations (HR, 1.12 per location; 95% CI, 1.00-1.25; P = .042). The factors associated with a lower hazard included increasing age (HR, 0.99 per increasing year; 95% CI, 0.98-1.0; P = .012) and an increasing number of preoperative diagnostic gastrointestinal studies (HR, 0.84 per study; 95% CI, 0.74-0.96; P = .012) Open and laparoscopic MALR resulted in similar long-term freedom from treatment failure. No radiographic parameters were associated with differences in treatment failure. CONCLUSIONS: No difference was found in long-term failure after open vs laparoscopic MALR; however, open release was associated with higher perioperative morbidity. These results support the use of a preoperative celiac plexus block to aid in patient selection. Operative candidates for MALR should be counseled regarding the factors associated with treatment failure and the relatively high overall rate of treatment failure.

Current status of pulmonary artery denervation.

Pulmonary hypertension is a progressive disease with a poor long-term prognosis and high mortality. Pulmonary artery denervation (PADN) is emerging as a potential novel therapy for this condition. The basis of pursuing a sympathetic denervation strategy has its origins in a body of experimental translation work that has demonstrated that denervation can reduce sympathetic nerve activity in various animal models. This reduction in pulmonary sympathetic nerve activity is associated with a reduction in pathological pulmonary hemodynamics in response to mechanical, pharmacological, and toxicologically induced pulmonary hypertension. The most common method of PADN is catheter-directed thermal ablation. Since 2014, there have been 12 reports on the role of PADN in 490 humans with pulmonary hypertension (311:179; treated: control). Of these, six are case series, three are randomized trials, and three are case reports. Ten studies used percutaneous PADN techniques, and two combined PADN with mitral and/or left atrial surgery. PADN treatment has low mortality and morbidity and is associated with an improved 6-minute walking distance, a reduction in both mean pulmonary artery pressure and pulmonary vascular resistance, and an improvement in cardiac output. These improved outcomes were seen over a median follow-up of 12 months (range 2-46 months). A recent meta-analysis of human trials also supports the effectiveness of PADN in carefully selected patients. Based on the current literature, PADN can be effective in select patients with pulmonary hypertension. Additional randomized clinical trials against best medical therapy are required.

Chemical and cryo-collection of muscle samples for transmission electron microscopy using Methacarn and dimethyl sulfoxide✰.

Muscle samples are commonly chemically fixed or frozen immediately upon collection for biochemical and morphological analysis. Certain fixatives such as glutaraldehyde and osmium tetroxide are widely used for transmission electron microscopy (TEM) and lead to adequate preservation of muscle ultrastructure, but do not preserve the molecular features of samples. Methacarn is suggested to be a preferable chemical fixative for light microscopy because it maintains immunohistological features of samples. However, the efficacy of methacarn to preserve ultrastructural features as a primary chemical fixative for TEM is currently unclear. Additionally, cryo-preservation of samples for TEM analysis involves freezing processes such as plunge freezing, slam freezing, or high pressure freezing. High pressure freezing is the considered the gold standard but requires costly equipment and may not be a viable option for many labs collecting tissue samples from remote locations. Dimethyl sulfoxide (DMSO) is a commonly used cryoprotectant that may allow for better structural preservation of samples by impairing ice damage that occurs during plunge/snap freezing. We aimed to assess the effectiveness of methacarn as a primary chemical fixative and determine the effect of pre-coating samples with DMSO before plunge/snap freezing tissues to be prepared for TEM. The micrographs of the methcarn-fixed samples indicate a loss of Z-disk integrity, intermyofibrillar space, mitochondria structure, and lipids. Ultimately, methacarn is not a viable primary fixative for tissue sample preparation for TEM. Similarly, liquid nitrogen freezing of samples wrapped in aluminum foil produced non-uniform Z-disk alignments that appeared smeared with swollen mitochondria. DMSO coating before freezing appears to lessen the alterations to contractile and mitochondrial morphological structures. DMSO appears to be useful for preserving the ultrastructure of sarcomeres if samples are covered before freezing.

MicroRNAs in peripheral artery disease: potential biomarkers and pathophysiological mechanisms.

Peripheral artery disease (PAD) is a disease of atherosclerosis in the lower extremities. PAD carries a massive burden worldwide, while diagnosis and treatment options are often lacking. One of the key points of research in recent years is the involvement of microRNAs (miRNAs), which are short 20-25 nucleotide single-stranded RNAs that can act as negative regulators of post-transcriptional gene expression. Many of these miRNAs have been discovered to be misregulated in PAD patients, suggesting a potential utility as biomarkers for PAD diagnosis. miRNAs have also been shown to play an important role in many different pathophysiological aspects involved in the initiation and progression of the disease including angiogenesis, hypoxia, inflammation, as well as other cellular functions like cell proliferation and migration. The research on miRNAs in PAD has the potential to lead to a whole new class of diagnostic tools and treatments.

High-Fat Diet Augments the Effect of Alcohol on Skeletal Muscle Mitochondrial Dysfunction in Mice.

Previous studies have shown that chronic heavy alcohol consumption and consumption of a high-fat (HF) diet can independently contribute to skeletal muscle oxidative stress and mitochondrial dysfunction, yet the concurrent effect of these risk factors remains unclear. We aimed to assess the effect of alcohol and different dietary compositions on mitochondrial activity and oxidative stress markers. Male and female mice were randomized to an alcohol (EtOH)-free HF diet, a HF + EtOH diet, or a low-Fat (LF) + EtOH diet for 6 weeks. At the end of the study, electron transport chain complex activity and expression as well as antioxidant activity and expression, were measured in skeletal muscles. Complex I and III activity were diminished in muscles of mice fed a HF + EtOH diet relative to the EtOH-free HF diet. Lipid peroxidation was elevated, and antioxidant activity was diminished, in muscles of mice fed a HF + EtOH diet as well. Consumption of a HF diet may exacerbate the negative effects of alcohol on skeletal muscle mitochondrial health and oxidative stress.

Skeletal muscle MiR-210 expression is associated with mitochondrial function in peripheral artery disease patients.

Previous studies have demonstrated that circulating microRNA (miR)-210 levels are elevated in peripheral artery disease (PAD) patients. MiR-210 is known to be a negative regulator of mitochondrial respiration; however, the relationship between miR-210 and mitochondrial function has yet to be studied in PAD. We aimed to compare skeletal muscle miR-210 expression of PAD patients to non-PAD controls (CON) and to examine the relationship between miR-210 expression and mitochondrial function. Skeletal muscle biopsies from CON (n = 20), intermittent claudication (IC) patients (n = 20), and critical limb ischemia (CLI) patients (n = 20) were analyzed by high-resolution respirometry to measure mitochondrial respiration of permeabilized fibers. Samples were also analyzed for miR-210 expression by real-time PCR. MiR-210 expression was significantly elevated in IC and CLI muscle compared to CON (P = 0.008 and P < 0.001, respectively). Mitochondrial respiration of electron transport chain (ETC) Complexes II (P = 0.001) and IV (P < 0.001) were significantly reduced in IC patients. Further, CLI patients demonstrated significant reductions in respiration during Complexes I (state 2: P = 0.04, state 3: P = 0.003), combined I and II (P < 0.001), II (P < 0.001), and IV (P < 0.001). The expression of the miR-210 targets, cytochrome c oxidase assembly factor heme A: farnesyltransferase (COX10), and iron-sulfur cluster assembly enzyme (ISCU) were down-regulated in PAD muscle. MiR-210 may play a role in the cellular adaptation to hypoxia and may be involved in the metabolic myopathy associated with PAD.

Management of Arterio-Venous Fistula Side Branches During Maturation: Ligation or Coil Embolization.

OBJECTIVE: Failure of maturation of arteriovenous fistulae (AVF) remains an ongoing concern for dialysis access. One etiology is the presence of side branches that divert flow from the main AVF channel. This study aims to evaluate the outcomes of endovascular and open surgical interventions for AVF side branches in the setting of maturation failure. METHODS: A retrospective review of all patients within a 10-year period with primary radio cephalic and brachiocephalic AVF was undertaken, and 380 cases of maturation failure related to branch diversion were selected for the study. Fifty-four percent and 48% of the AVF in the ENDO and OPEN groups respectively have concomitant stenosis further along in the flow path that required intervention by balloon angioplasty at the same time as a side branch intervention. All patients underwent duplex imaging or a fistulogram before intervention. Indications were low flow (<600 mL/min) or failure to increase in size (<6 mm diameter) in all cases. Interventions were divided into endovascular (coil embolization; ENDO) and surgical (branch ligation; OPEN) interventions. Outcomes of maturation (successful progression to hemodialysis (HD)), re-intervention, and functional dialysis (continuous HD for three consecutive months) were examined. RESULTS: From January 2008 to December 2018, 187 patients (49^ of all cases with side branches; 65% female, age of 57 ± 18 years; mean ± SD) with poorly maturing radiocephalic (70%) and brachiocephalic AVF (30%) underwent intervention due to the presence of accessory venous branches only. Indications were failure to mature in 54% and low flow in 46%. The average time to intervention due to failure to mature was 5 ± 4 weeks (mean ± SD) after primary access placement. Eighty-one had coil embolization and 106 had open branch ligation. Technical success was 90% in ENDO and 100% in OPEN. Technical ENDO failures had a secondary open branch ligation but were considered failures for analysis. Repeat interventions by balloon-assisted maturation were required in 45% of all the cases with no difference between ENDO and OPEN. Recannulation of the ENDO branches occurred in 10% of the cases requiring repeat intervention. Sixty one percent of isolated endovascular (n = 49) and 64% of isolated open (n = 68) matured to successful cannulation (P = 0.84). Median functional dialysis durations remained equivalent between ENDO (2.6 years) and OPEN (2.8 years) groups (P = 0.12). CONCLUSION: There is an improved maturation rate following the ENDO group compared to OPEN interventions while both ENDO and OPEN modalities demonstrated similar long-term functionality.

Endothelial cell-derived pro-fibrotic factors increase TGF-ß1 expression by smooth muscle cells in response to cycles of hypoxia-hyperoxia.

BACKGROUND: The vascular pathology of peripheral artery disease (PAD) encompasses abnormal microvascular architecture and fibrosis in response to ischemia-reperfusion (I/R) cycles. We aimed to investigate the mechanisms by which pathological changes in the microvasculature direct fibrosis in the context of I/R. METHODS: Primary human aortic endothelial cells (ECs) were cultured under cycles of normoxia-hypoxia (NH) or normoxia-hypoxia-hyperoxia (NHH) to mimic I/R. Primary human aortic smooth muscle cells (SMCs) were cultured and treated with media from the ECs. FINDINGS: The mRNA and protein expression of the pro-fibrotic factors platelet derived growth factor (PDGF)-BB and connective tissue growth factor (CTGF) were significantly upregulated in ECs undergoing NH or NHH cycles. Treatment of SMCs with media from ECs undergoing NH or NHH cycles led to significant increases in TGF-ß1, TGF-ß pathway signaling intermediates, and collagen expression. Addition of neutralizing antibodies against PDGF-BB and CTGF to the media blunted the increases in TGF-ß1 and collagen expression. Treatment of SMCs with PAD patient-derived serum also led to increased TGF-ß1 levels. INTERPRETATION: In an in-vitro model of I/R, which recapitulates the pathophysiology of PAD, increased secretion of PDGF-BB and CTGF by ECs was shown to be predominantly driving TGF-ß1-mediated expression by SMCs. These cell culture experiments help elucidate the mechanism and interaction between ECs and SMCs in microvascular fibrosis associated with I/R. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of I/R. FUNDING: National Institute on Aging at the National Institutes of Health grant number R01AG064420. RESEARCH IN CONTEXT: Evidence before this study: Previous studies in gastrocnemius biopsies from peripheral artery disease (PAD) patients showed that transforming growth factor beta 1 (TGF-ß1), the most potent inducer of pathological fibrosis, is increased in the vasculature of PAD patients and correlated with collagen deposition. However, the exact cellular source of TGF-ß1 remained unclear. Added value of this study: Exposing cells to cycles of normoxia-hypoxia-hyperoxia (NHH) resulted in pathological changes that are consistent with human PAD. This supports the idea that the use of NHH may be a reliable, novel in vitro model of PAD useful for studying associated pathophysiological mechanisms. Furthermore, pro-fibrotic factors (PDGF-BB and CTGF) released from endothelial cells were shown to induce a fibrotic phenotype in smooth muscle cells. This suggests a potential interaction between these cell types in the microvasculature that drives increased TGF-ß1 expression and collagen deposition. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of ischemia-reperfusion.

Phytochemicals as Therapeutic Interventions in Peripheral Artery Disease.

Peripheral artery disease (PAD) affects over 200 million people worldwide, resulting in significant morbidity and mortality, yet treatment options remain limited. Among the manifestations of PAD is a severe functional disability and decline, which is thought to be the result of different pathophysiological mechanisms including oxidative stress, skeletal muscle pathology, and reduced nitric oxide bioavailability. Thus, compounds that target these mechanisms may have a therapeutic effect on walking performance in PAD patients. Phytochemicals produced by plants have been widely studied for their potential health effects and role in various diseases including cardiovascular disease and cancer. In this review, we focus on PAD and discuss the evidence related to the clinical utility of different phytochemicals. We discuss phytochemical research in preclinical models of PAD, and we highlight the results of the available clinical trials that have assessed the effects of these compounds on PAD patient functional outcomes.

Extent of heel ulceration influences the outcomes in patients with isolated infrapopliteal limb threatening critical ischemia.

BACKGROUND: The aim of the present study was to assess the effects of the extent of heel ulceration on the outcomes of limb threatening critical ischemia due to isolated infrapopliteal disease. METHODS: A retrospective review identified 989 patients with isolated infrapopliteal disease and heel ulceration treated from 2001 to 2018. The heel was defined as the back of the foot, extending from the Achilles tendon to around the plantar surface and covering the apex of the calcaneum bone. Heel ulceration was categorized into three groups by area: <5 cm2, 5 to 10 cm2, and >10 cm2. The interventions were endovascular, open bypass, major amputation, and wound care. An intention-to-treat analysis by patient group was performed. The 30-day outcomes and amputation-free survival (AFS; survival without a major amputation) were evaluated. RESULTS: Of the 989 patients, 384 (58% male; average age, 65 years; n = 768 vessels) had undergone isolated endovascular tibial intervention, 124 (45% male; average age, 59 years) had undergone popliteal tibial vein bypass for limb threatening critical ischemia, 219 (52% male; average age, 67 years) had undergone major amputation, and 242 (49% male; average age, 66 years) had received wound care. No difference was found in the 30-day major adverse cardiac events in the endovascular and open bypass groups, with significantly more events in the major amputation group (P = .03). The 30-day major adverse limb events and 30-day amputation rates were equivalent between the open bypass and endovascular groups. The 5-year AFS rate was superior in the open bypass group (37% ± 8%; mean ± standard error of the mean) compared with the endovascular group (27% ± 9%; P = .04). The wound care group had a 5-year AFS rate of 20% ± 9%, which was not significantly different from that of the endovascular group. Patients with heel ulcers of <5 cm2 had better AFS (47% ± 8%) than those with 5- to 10- cm2 heel ulceration (24% ± 9%). Heel ulcers >10 cm2 were associated with markedly worse 5-year AFS outcomes (0% ± 0%). The presence of end-stage renal disease, osteomyelitis, uncontrolled diabetes (hemoglobin A1c >10%), and/or frailty combined with a heel ulcer >10 cm2 were predictive of poor AFS. CONCLUSIONS: An increasing heel ulcer area combined with osteomyelitis and systemic comorbidities was associated with worsening 30-day outcomes and 5-year AFS, irrespective of the therapy chosen.

The "two-cut monorail" technique, for the over-the-wire removal of the Impella CP device.

The Impella is a percutaneously placed intra-arterial flow pump positioned across the aortic valve for circulatory support. A limitation of the Impella is that it lacks a central wire channel, to maintain intra-arterial wire access when removing the device. Open surgical arterial cutdown is needed for the removal of the Impella CP placed emergently, without the use of preclose sutures. This case review describes an alternative removal method for the aforementioned occasions.

Renal salvage using stent graft placement after acute renal artery occlusion with prolonged ischemic time.

PURPOSE: To describe a patient with acute renal artery occlusion who underwent successful revascularization procedure after experiencing a protracted ischemic period, which resulted in successful retrieval of renal function. CASE REPORT: A 58-year-old male with a history of left renal artery stenosis and stent graft placement presented with symptoms of chest pain, shortness of breath, and flank pain. The patient was admitted to the Intensive Care Unit with the diagnosis of multiorgan failure and subsequent anuria that led to the initiation of hemodialysis. Computed tomography angiography demonstrated an aortic occlusion along with bilateral proximal renal artery occlusion with reconstitution of the mid to distal renal arteries via collateralization. The patient underwent angioplasty with bilateral renal artery stent-graft placement and successful revascularization of proximal renal arteries. Post-operatively, his renal function and urine output improved, and the patient was able to be weaned off hemodialysis along with the benefit of concurrent amelioration of his renovascular hypertension. CONCLUSION: For select patients with renal artery occlusion, revascularization of the renal arteries may result in dialysis independence and stabilization of renovascular hypertension, despite prolonged time of ischemia.

The Nitric Oxide System in Peripheral Artery Disease: Connection with Oxidative Stress and Biopterins.

Peripheral artery disease (PAD) pathophysiology extends beyond hemodynamics to include other operating mechanisms, including endothelial dysfunction. Oxidative stress may be linked to endothelial dysfunction by reducing nitric oxide (NO) bioavailability. We aimed to investigate whether the NO system and its regulators are altered in the setting of PAD and to assess the relationship between NO bioavailability and oxidative stress. Sera from 35 patients with intermittent claudication (IC), 26 patients with critical limb ischemia (CLI), and 35 non-PAD controls were analyzed to determine levels of tetrahydrobiopterin (BH4), dihydrobiopterin (BH2), nitrate/nitrite (nitric oxides, or NOx), arginine, citrulline, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), and the oxidative stress markers 8-Oxo-2'-deoxyguanosine (8-OHdG), 4-hydroxynonenal (4-HNE), advanced glycation end products (AGEs), and protein carbonyls. NOx was significantly lower in IC and CLI patients compared to controls in association with elevated oxidative stress, with the greatest NOx reductions observed in CLI. Compared with controls, IC and CLI patients had reduced BH4, elevated BH2, and a reduced BH4/BH2 ratio. SDMA, the arginine/SDMA ratio, and the arginine/ADMA ratio were significantly higher in CLI patients. The NO system and its regulators are significantly compromised in PAD. This dysregulation appears to be driven by increased oxidative stress and worsens as the disease progresses from claudication to CLI.

Implications of early failure of isolated endovascular tibial interventions.

BACKGROUND: Endovascular tibial interventions for chronic limb-threatening ischemia are frequent, but the implications of early failure (≤30 days) of an isolated tibial intervention are still unclear. The aim of this study was to examine the patient-centered outcomes after early failure of isolated tibial artery intervention. METHODS: A database of patients undergoing lower extremity endovascular interventions between 2007 and 2017 was retrospectively queried. Patients with chronic limb-threatening ischemia (Rutherford classes 4, 5, and 6) were selected, and failures within 30 days were identified. Lack of technical success at the time of the procedure was an exclusion. Intention-to-treat analysis by patient was performed. Patient-oriented outcomes of clinical efficacy (absence of recurrent symptoms, maintenance of ambulation, and absence of major amputation), amputation-free survival (survival without major amputation), and freedom from major adverse limb events (MALEs; above-ankle amputation of the index limb or major reintervention [new bypass graft, jump or interposition graft revision]) were evaluated. RESULTS: There were 1779 patients (58% male; average age, 65 years; 2898 vessels) who underwent tibial intervention for chronic limb-threatening ischemia; 284 procedures (16%) were early failures. In the early failure group, 124 cases (44%) were considered immediate (<24 hours), and 160 cases (56%) failed within the first 30 days after intervention. The two modes of failure were hemodynamic failure (47%) and progression of chronic limb-threatening ischemia (53%). Bypass after early failure was successful in patients with adequate vein, target vessel of ≥3 mm, and good inframalleolar runoff. Progression of symptoms was associated with major amputation in patients with Rutherford class 5 and class 6 disease. Presentation with diabetes and end-stage renal disease were identified as independent clinical predictors for early failure. Lesion calcification, reference vessel diameter <3 mm, lesion length >300 mm, and poor inframalleolar runoff were identified as independent anatomic predictors for early failure and increased MALEs. Early failure was predictive of poor long-term clinical efficacy (11% ± 9% vs 39% ± 8% at 5 years, mean ± standard error of the mean, early vs no early failure; P = .01) and amputation-free survival (16% ± 9% vs 47% ± 9% at 5 years, mean ± standard error of the mean, early vs no early failure; P = .02). CONCLUSIONS: Both clinical and anatomic factors can predict early failure of endovascular therapy for isolated tibial disease. Early failure significantly increases 30-day major amputation and 30-day MALEs and is associated with poor long-term patient-centered outcomes.

Short-term contemporary outcomes for staged versus primary lower limb amputation in diabetic foot disease.

BACKGROUND: Major lower extremity amputations remain among the most common procedures performed by vascular surgeons in patients with diabetes and its associated peripheral vascular disease. After major amputation, this population commonly suffers from high readmission rates, increased wound complications, and conversion to more proximal major amputations. These events impact quality in terms of cost, resources, and subjective quality of life. The aim of this study is to compare outcomes between primary lower extremity above-ankle amputations (primary amputation [PA]) and staged ankle guillotine amputations followed by interval formalization to an above-ankle amputation (staged amputation [SA]) for nonsalvageable infected diabetic foot disease. METHODS: A retrospective review of all de novo major lower extremity amputations performed by the vascular surgery service at a single institution between January 2014 and March 2017 was performed. Inclusion criteria were diabetic patients with foot gangrene who underwent a major de novo above- or below-knee amputation. Amputations for trauma, acute limb ischemia, or malignancy were excluded. Per institutional practice, SA was performed for uncontrolled infection and/or infection with uncontrolled diabetes, and PA was performed in the absence of active infection and in stable diabetes. The primary outcome measure was 30-day freedom from conversion to a higher level amputation. Secondary outcome measures were 30-day stump complications, 30-day readmissions, 30-day major adverse cardiovascular events, and 30-day mortality. RESULTS: One hundred sixteen patients met the inclusion criteria. Sixty-eight percent were male, 18% were active smokers, 30% had end-stage renal disease, and 22% had congestive heart failure. Sixty-one patients underwent SA, and 55 patients underwent PA. The two cohorts were well-matched by demographics and comorbidities. Consistent with the institutional practice, 57% of SA patients met two or more systemic inflammatory response syndrome criteria at presentation compared with 24% of PA patients (P = .0003). There were no 30-day mortalities. There was no significant difference in major adverse cardiovascular events between the groups (2% vs 4%; SA vs PA, respectively; P = .6). The average length of stay did not significantly differ between SA and PA (mean of 14 ± 8 days vs 11 ± 11 days; P = .1). SA patients had a lower rate of 30-day readmission (7% vs 27%; P = .005) and 30-day unplanned conversion to higher level amputation (2% vs 13%; P = .026) compared with PA patients. CONCLUSIONS: In the setting of infected diabetic foot disease, a staged lower extremity amputation achieves quality outcomes superior to a one-stage amputation, despite the former cohort's greater illness acuity level. SA should be considered in all diabetic patients presenting with active foot infection.

Novel open technique for repair of endograft migration.

Widespread adoption of endovascular aneurysm repair has led to increased incidence of late complications, such as endograft migration. Treatment options have to be tailored to the patient's health, quality of proximal aorta, and extent of migration. Complete or partial endograft removal is associated with significant morbidity and mortality. We describe a case in which open repair with endograft preservation was employed, with the additional benefit of a sutured proximal anastomosis.