Impact of COVID-19 on patients undergoing scheduled procedures for chronic venous disease

OBJECTIVE

The COVID-19 pandemic has drastically altered the medical landscape. Various strategies have been employed to preserve hospital beds, personal protective equipment, and other resources to accommodate the surges of COVID-19 positive patients, hospital overcapacities, and staffing shortages. This has had a dramatic effect on vascular surgical practice. The objective of this study is to analyze the impact of the COVID-19 pandemic on surgical delays and adverse outcomes for patients with chronic venous disease scheduled to undergo elective operations.

METHODS

The Vascular Surgery COVID-19 Collaborative (VASCC) was founded in March 2020 to evaluate the outcomes of patients with vascular disease whose operations were delayed. Modules were developed by vascular surgeon working groups and tested before implementation. A data analysis of outcomes of patients with chronic venous disease whose surgeries were postponed during the COVID-19 pandemic from March 2020 through February 2021 was performed for this study.

RESULTS

A total of 150 patients from 12 institutions in the United States were included in the study. Indications for venous intervention were: 85.3% varicose veins, 10.7% varicose veins with venous ulceration, and 4.0% lipodermatosclerosis. One hundred two surgeries had successfully been completed at the time of data entry. The average length of the delay was 91 days, with a median of 78 days. Delays for venous ulceration procedures ranged from 38 to 208 days. No patients required an emergent intervention due to their venous disease, and no patients experienced major adverse events following their delayed surgeries.

CONCLUSIONS

Interventions may be safely delayed for patients with venous disease requiring elective surgical intervention during the COVID-19 pandemic. This finding supports the American College of Surgeons' recommendations for the management of elective vascular surgical procedures. Office-based labs may be safe locations for continued treatment when resources are limited. Although the interventions can be safely postponed, the negative impact on quality of life warrants further investigation.

Ceramides in peripheral arterial plaque lead to endothelial cell dysfunction

Background

Peripheral arterial atheroprogression is increasingly prevalent, and is a risk factor for major limb amputations in individuals with risk factors such as diabetes. We previously demonstrated that bioactive lipids are significantly altered in arterial tissue of individuals with diabetes and advanced peripheral arterial disease.

Methods

Here we evaluated whether sphingolipid ceramide 18:1/16:0 (C16) is a cellular regulator in endothelial cells and peripheral tibial arterial tissue in individuals with diabetes.

Results

We observed that C16 is the single most elevated ceramide in peripheral arterial tissue from below the knee in individuals with diabetes (11% increase, P < .05). C16 content in tibial arterial tissue positively correlates with sphingomyelin (SPM) content in patients with and without diabetes (r2 = 0.5, P < .005; r2 = 0.17, P < .05; respectively). Tibial arteries of individuals with diabetes demonstrated no difference in CERS6 expression (encoding ceramide synthase 6; the predominate ceramide synthesis enzyme), but higher SMPD expression (encoding sphingomyelin phosphodiesterase that catalyzes ceramide synthesis from sphingomyelins; P < .05). SMPD4, but not SMPD2, was particularly elevated in maximally diseased (Max) tibial arterial segments (P < .05). In vitro, exogenous C16 caused endothelial cells (HUVECs) to have decreased proliferation (P < .03), increased apoptosis (P < .003), and decreased autophagy (P < .008). Selective knockdown of SMPD2 and SMPD4 decreased native production of C16 (P < .01 and P < .001, respectively), but only knockdown of SMPD4 rescued cellular proliferation (P < .005) following exogenous supplementation with C16.

Conclusions

Our findings suggest that C16 is a tissue biomarker for peripheral arterial disease severity in the setting of diabetes, and can impact endothelial cell viability and function.

Clinical relevance

Peripheral arterial disease and its end-stage manifestation known as chronic limb-threatening ischemia (CLTI) represent ongoing prevalent and intricate medical challenges. Individuals with diabetes have a heightened risk of developing CLTI and experiencing its complications, including wounds, ulcers, and major amputations. In the present study, we conducted a comprehensive examination of the molecular lipid composition within arterial segments from individuals with CLTI, and with and without diabetes. Our investigations unveiled a striking revelation: the sphingolipid ceramide 18:1/16:0 emerged as the predominant ceramide species that was significantly elevated in the peripheral arterial intima below the knee in patients with diabetes. Moreover, this heightened ceramide presence is associated with a marked impairment of endothelial cell function and viability. Additionally, our study revealed a concurrent elevation in the expression of sphingomyelin phosphodiesterases, enzymes responsible for catalyzing ceramide synthesis from sphingomyelins, within maximally diseased arterial segments. These findings underscore the pivotal role of ceramides and their biosynthesis enzymes in the context of CLTI, offering new insights into potential therapeutic avenues for managing this challenging disease process.

Altered Peroxisome Proliferator-Activated Receptor Alpha Signaling in Variably Diseased Peripheral Arterial Segments

Objective

Peripheral atherosclerosis that accumulates in the extracranial carotid and lower extremity arteries can lead to significant morbidity and mortality. However, atherosclerotic disease progression is often not homogenous and is accelerated by diabetes. We previously observed increased phospholipid content in minimally (Min)-diseased arterial segments compared to maximally (Max)-diseased segments. Since Peroxisome Proliferator-Activated Receptor alpha (PPARα) is a key regulator of lipid metabolism, we hypothesized that it may have differential expression and signaling in Min vs. Max-diseased peripheral arterial segments.

Methods

Eighteen patients who underwent carotid endarterectomy (CEA), and 34 patients who underwent major lower extremity amputation were prospectively enrolled into a vascular tissue biobank. Min and Max-diseased segments were obtained in real-time from CEA plaque and amputated lower extremity arterial segments. mRNA and protein were isolated from specimens and the relative expression of ppara, and its downstream genes Acyl-CoA Oxidase 1 (acox1) and Carnitine Palmitoyltransferase 1A (cpt1a) were also evaluated. We evaluated gene expression and protein content relative to atherosclerotic disease severity and clinical diabetes status. Gene expression was also evaluated relative to Hemoglobin A1c and serum lipid profiles.

Results

In CEA segments of patients with diabetes, we observed significantly higher ppara and acox1 gene expression (p < 0.01 and p < 0.001 respectively), and higher PPARα protein content (p < 0.05). Hemoglobin A1c significantly correlated with expression of ppara (R² = 0.66, p < 0.001), acox1 (R² = 0.31, p < 0.05), and cpt1a (R² = 0.4, p < 0.05). There was no significant difference in gene expression between Min vs. Max-diseased CEA plaque segments. Conversely, in lower extremity arterial segments of patients with diabetes, we observed significantly lower ppara, acox1, and cpt1a expression (p < 0.05, p < 0.001, and p < 0.0001 respectively). Interestingly, CPT1A content was lower in arterial segments of patients with diabetes (p < 0.05). Hemoglobin A1c and HDL-cholesterol had negative correlations with ppara (R² = 0.44, p < 0.05; R² = 0.42, p < 0.05; respectively).

Conclusion

This study demonstrates the significant differential expression of ppara and its immediate downstream genes in human carotid and lower extremity arteries relative to disease severity and diabetes. These findings highlight that mechanisms that influence atheroprogression in the carotid and lower extremities peripheral arteries are not homogenous and can be impacted by patient diabetes status and serum cholesterol profiles. Further elucidating these differential molecular mechanisms can help improve targeted therapy of atherosclerosis in different peripheral arterial beds.

Comprehensive Assessment of Current Management Strategies for Patients With Diabetes and Chronic Limb-Threatening Ischemia

Chronic limb-threatening ischemia (CLTI) is the most severe form of peripheral artery disease. It is estimated that 60% of all nontraumatic lower-extremity amputations performed annually in the United States are in patients with diabetes and CLTI. The consequences of this condition are extraordinary, with substantial patient morbidity and mortality and high socioeconomic costs. Strategies that optimize the success of arterial revascularization in this unique patient population can have a substantial public health impact and improve patient outcomes. This article provides an up-to-date comprehensive assessment of management strategies for patients afflicted by both diabetes and CLTI.

Abstract MP25: Differential Expression Of Pparα In Peripheral Arterial Segments Of Patients With Advanced Atherosclerosis

Peripheral atherosclerosis manifests in both the extracranial carotid and lower extremity arteries and can lead to significant morbidity and mortality. However, atherosclerotic disease progression is often not homogenous and is accelerated by diabetes. We previously observed altered phospholipodomic profiles between minimally (MIN) and maximally (MAX) diseased peripheral arterial segments. Since Peroxisome Proliferator-Activated Receptor alpha ( pparα ) is a key regulator of lipid metabolism, we hypothesized that it may have variable content and signaling in MIN and MAX diseased arterial segments. To test our hypothesis, 12 patients who underwent carotid endarterectomy (CEA), and 19 patients who underwent major lower extremity amputation were recruited. MIN and MAX disease segments were obtained in real time from the operating room from CEA plaque and arterial segments from amputated lower extremities. mRNA was isolated from all specimens and relative content of pparα , Acyl-CoA Oxidase 1 ( acox1 ) , and Carnitine Palmitoyltransferase 1A ( cpt1a ) were evaluated. We observed significantly higher pparα expression in CEA segments in patients with diabetes (p < 0.01), as well as higher acox1 (p < 0.001) and cpt1a (p < 0.05) expression (A-C). Hemoglobin A1C had a significant correlation with ppara gene expression. There was no significant difference in gene expression between MAX and MIN diseased CEA plaque segments. Interestingly, we observed that in lower extremity arterial segments there was no difference in ppara , acox1 , and cpt1a in patients with and without diabetes, but downstream genes were significantly increased in MAX diseased arterial segments (D-F). This study demonstrates the variable expression pattern of pparα and its downstream genes in human peripheral arteries. Our findings suggest variable gene expression in different peripheral arterial beds, which may have an impact on mechanisms of disease progression and pharmacologic targeting.

A systematic review and meta-analysis of outcomes after acute limb ischemia in patients with cancer

BACKGROUND

Cancer results in a hypercoagulable state that is associated with both venous and arterial thromboses. However, little is known about the effects of acute limb ischemia (ALI) in this cohort of patients. In the present systematic review and meta-analysis, we analyzed the available clinical data on cancer and its association with ALI and evaluated the outcomes in these patients after a diagnosis of ALI.

METHODS

Three databases, including PubMed, EMBASE, and the Cochrane Library, were queried. Studies that met the inclusion criteria were included regardless of the publication year, language, sample size, or follow-up length. All the steps of the meta-analysis were conducted in accordance with the PRISMA (preferred reporting items for systematic reviews and meta-analyses) and MOOSE (meta-analysis of observational studies in epidemiology) guidelines.

RESULTS

Seven studies from 6222 references with a total of 2899 patients were included. Of the 2899 patients, 1195 (41%) had had a diagnosis of ALI before their cancer diagnosis, and 1704 (59%) had presented with ALI after a cancer diagnosis. Nearly three quarters of ALI events were among patients with cancer of the skin and soft tissue (19%), genitourinary (18%), lung (17%), and gastrointestinal (16%) systems. ALI recurrence was similar between the two groups, and major amputation was more likely in patients with a diagnosis of ALI after a cancer diagnosis (7.4% vs 4.6%; P < .01). The incidence of mortality at 1 year was significantly greater for patients with established cancer who had presented with ALI compared with the patients who had presented with ALI before a cancer diagnosis (50.6% vs 29.9%; P < .01). After adjusting for study variability using the random effects model, the mortality at 1 year for all patients was 52.3% (95% confidence interval, 37.7%-66.5%). No significant heterogeneity (P = .73) was found between the two groups of patients, which varied by the timing of the ALI diagnosis in relation to the cancer diagnosis.

CONCLUSIONS

The 1-year mortality after the development of ALI in patients with cancer was >50%. For patients presenting with ALI of unclear etiology, the presence of an underlying cancer should be considered.

CEPT1-Mediated Phospholipogenesis Regulates Endothelial Cell Function and Ischemia-Induced Angiogenesis Through PPARα

De novo phospholipogenesis, mediated by choline-ethanolamine phosphotransferase 1 (CEPT1), is essential for phospholipid activation of transcription factors such as peroxisome proliferator-activated receptor α (PPARα) in the liver. Fenofibrate, a PPARα agonist and lipid-lowering agent, decreases amputation incidence in patients with diabetes. Because we previously observed that CEPT1 is elevated in carotid plaque of patients with diabetes, we evaluated the role of CEPT1 in peripheral arteries and PPARα phosphorylation (Ser12). CEPT1 was found to be elevated in diseased lower-extremity arterial intima of individuals with peripheral arterial disease and diabetes. To evaluate the role of Cept1 in the endothelium, we engineered a conditional endothelial cell (EC)-specific deletion of Cept1 via induced VE-cadherin-CreERT2-mediated recombination (Cept1Lp/LpCre ⁺). Cept1Lp/LpCre ⁺ ECs demonstrated decreased proliferation, migration, and tubule formation, and Cept1Lp/LpCre ⁺ mice had reduced perfusion and angiogenesis in ischemic hind limbs. Peripheral ischemic recovery and PPARα signaling were further compromised by streptozotocin-induced diabetes and ameliorated by feeding fenofibrate. Cept1 endoribonuclease-prepared siRNA decreased PPARα phosphorylation in ECs, which was rescued with fenofibrate but not PC16:0/18:1. Unlike Cept1Lp/LpCre ⁺ mice, Cept1Lp/LpCre ⁺ Ppara ^-/- mice did not demonstrate hind-paw perfusion recovery after feeding fenofibrate. Therefore, we demonstrate that CEPT1 is essential for EC function and tissue recovery after ischemia and that fenofibrate rescues CEPT1-mediated activation of PPARα.

Canagliflozin impedes ischemic hind-limb recovery in the setting of diabetes

There is a reported increased incidence of lower extremity amputations in individuals with diabetes who are treated with canagliflozin (an SGLT2 receptor inhibitor). It is unclear whether this is an unintended consequence of therapy, or whether canagliflozin can affect peripheral limb perfusion in the setting of underling arterial malperfusion. To evaluate this we explored the effect of canagliflozin on tissue recovery following unilateral hind-limb ischemia (HLI). Adult wildtype (+/+) and diabetic (db/db) mice were maintained on 8 weeks of a regular chow diet, or a chow diet containing canagliflozin (200 mg/kg). Following HLI, hind-limb appearance, function, and Doppler perfusion were serially evaluated. Gastrocnemius muscle fiber size and microvessel density were also evaluated 21 days following HLI. We observed that db/db that received a diet containing canagliflozin had significantly worse hind-limb function and appearance scores compared to both db/db mice that received a regular diet and +/+ mice that received a canagliflozin diet. At post-HLI day 21, db/db mice that received a canagliflozin diet also had decreased Doppler perfusion, gastrocnemius muscle fiber size, and microvessel density compared to +/+ mice that received a canagliflozin diet. These findings indicate that canagliflozin appears to impede ischemic peripheral tissue recovery and warrant further clinical investigation in individuals with diabetes and a history of peripheral artery disease.

Circulating serum fatty acid synthase is elevated in patients with diabetes and carotid artery stenosis and is LDL-associated

BACKGROUND AND AIMS

Diabetes is an independent risk factor for carotid artery stenosis (CAS). Fatty acid synthase (FAS), an essential de novo lipogenesis enzyme, has increased activity in the setting of diabetes that leads to altered lipid metabolism. Circulating FAS (cFAS) was recently observed in the blood of patients with hyperinsulinemia and cancer. We thought to evaluate the origin of cFAS and its role in diabetes-associated CAS.

METHODS

Patients with diabetes and no diabetes, undergoing carotid endarterectomy (CEA) for CAS, were prospectively enrolled for collection of plaque and fasting serum. FPLC was used to purify lipoprotein fractions, and ELISA was used to quantify cFAS content and activity. Immunoprecipitation (IP) was used to evaluate the affinity of cFAS to LDL-ApoB.

RESULTS

Patients with CAS had higher cFAS activity (p < 0.01), and patients with diabetes had higher cFAS activity than patients with no diabetes (p < 0.05). cFAS activity correlated with serum glucose (p = 0.03, r² = 0.35), and cFAS content trended with plaque FAS content (p = 0.06, r² = 0.69). cFAS was predominantly in LDL cholesterol fractions of patients with CAS (p < 0.001), and IP of cFAS demonstrated pulldown of ApoB. Similar to patients with diabetes, db/db mice had highest levels of serum cFAS (p < 0.01), and fasL^-/- (tissue-specific liver knockdown of FAS) mice had the lowest levels of cFAS (p < 0.001).

CONCLUSIONS

Serum cFAS is higher in patients with diabetes and CAS, appears to originate from the liver, and is LDL cholesterol associated. We postulate that LDL may be serving as a carrier for cFAS that contributes to atheroprogression in carotid arteries of patients with diabetes.