Saphenous vein grafts in contemporary coronary artery bypass graft surgery

Coronary angiography was used to assess the effect of diabetes on off-pump coronary artery bypass graft patency

This study aimed to examine the influence of diabetes on the left internal mammary artery (LIMA) and saphenous vein (SV) graft failure for 5-year follow-up. We enrolled 202 patients who underwent isolated off-pump coronary artery bypass grafting (CABG) surgery in 2014, angiographic follow-up occurred at 5 years after surgery. Angiographic outcomes in patients with or without diabetes were analyzed. Multivariate logistic regression analysis was used to identify independent predictors of graft dysfunction. A total of 66 (32.7%) patients had diabetes. Five-year rates of LIMA and SV graft failure were similar in patients with and without diabetes. In addition, in diabetics, the proportion of complete graft failure was significantly lower in the LIMA grafts (12/66, 18.2%) than in the SV grafts (57/133, 42.9%) (P = .001). In nondiabetic, the proportion of complete graft failure was also significantly lower in the LIMA grafts (28/136, 20.6%) than in the SV grafts (105/275, 38.2%) (P < .001). Multivariate logistic regression analysis showed that mean graft flow (MGF) was an independent predictor factor for LIMA (odds ratio = 1.186, 95% CI = 1.114-1.263, P < .001) and SV (odds ratio = 1.056, 95% CI = 1.035-1.077, P < .001) graft failure. Diabetes did not influence the patency of LIMA or SV grafts over a 5-year follow-up. LIMA grafts should be maximized in patients undergoing off-pump CABG surgery. Diabetes does not affect the patency of grafts CABG. Using angiography, our study proved that diabetes does not affect the patency of grafted vessels after CABG for 5 years.

Effect of patent complete revascularization on the akinetic myocardial segments

OBJECTIVES

The aims of the study were (i) to examine the changes in echocardiographic parameters and (ii) to compare the fate of myocardial segments with akinesia and without akinesia on preoperative echocardiography after coronary artery bypass grafting.

METHODS

One hundred one patients who underwent complete revascularization, who were assessed by preoperative, before discharge, postoperative 3- and 12-month echocardiographic examinations, and who showed all patent grafts at postoperative 1-year angiograms were included. Echocardiographic left ventricular ejection fraction was assessed, and a 16-segment model was adopted for regional analysis of the left ventricle. A total of 1616 segments were analysed based on a 6-point scale: 1 = normal (N = 1083), 2 = mild hypokinesia (N = 2), 3 = moderate hypokinesia (N = 74), 4 = severe hypokinesia (N = 150), 5 = akinesia without thinning (N = 259) and 6 = akinesia with thinning (N = 48).

RESULTS

The serial left ventricular ejection fraction measured preoperatively, before discharge, at postoperative 3- and 12-months were 0.48 ± 0.14, 0.49 ± 0.12, 0.49 ± 0.10 and 0.54 ± 0.10, respectively. The left ventricular ejection fraction significantly increased over time during the postoperative 12 months (P < 0.001). Wall motion scores tended to decrease over time in both segment groups with akinesia and without akinesia (P < 0.001), and improvement of the wall motion was significantly higher in the segment group with akinesia than in the segment group without akinesia (P < 0.001).

CONCLUSIONS

The left ventricular ejection fraction and regional wall motion improved over time during the postoperative 12 months, regardless of the presence of an akinetic segment. Complete revascularization including akinetic myocardium should be considered when performing coronary artery bypass grafting.

Additive Manufacturing of Biodegradable Molybdenum - From Powder to Vascular Stent

Magnesium, iron, and zinc-based biodegradable metals are widely recognized as promising candidate materials for the next generation of bioresorbable stent (BVS). However, none of those metal BVSs are perfect at this stage. Here, a brand-new BVS based on a novel biodegradable metal (Molybdenum, Mo) through additive manufacturing is developed. Nearly full-dense and crack-free thin-wall Mo is directly manufactured through selective laser melting (SLM) with fine Mo powder. Systemic analyses considering the forming quality, wall-thickness, microstructure, mechanical properties, and in vitro degradation behaviors are performed. Then, Mo-based thin-strut (≤ 100 µm) stents are successfully obtained through an optimized single-track laser melting route. The SLMed thin-wall Mo owns comparable strength to its Mg and Zn based counterparts (as-drawn), while, it exhibits remarkable biocompatibility in vitro. Vessel related cells are well adhered and spread on SLMed Mo, and it exhibits a low risk of hemolysis and thrombus. The SLMed stent is compatible to vessel tissues in rat abdominal aorta, and it can provide sufficient support in an animal model as an extravascular stent. This work possibly opens a new era of manufacturing Mo-based stents through additive manufacturing.

A bypass flow model to study endothelial cell mechanotransduction across diverse flow environments

Disturbed flow is one of the pathological initiators of endothelial dysfunction in intimal hyperplasia (IH) which is commonly seen in vascular bypass grafts, and arteriovenous fistulas. Various in vitro disease models have been designed to simulate the hemodynamic conditions found in the vasculature. Nonetheless, prior investigations have encountered challenges in establishing a robust disturbed flow model, primarily attributed to the complex bifurcated geometries and distinctive flow dynamics. In the present study, we aim to address this gap by introducing an in vitro bypass flow model capable of inducing disturbed flow and other hemodynamics patterns through a pulsatile flow in the same model. To assess the model's validity, we employed computational fluid dynamics (CFD) to simulate hemodynamics and compared the morphology and functions of human umbilical venous endothelial cells (HUVECs) under disturbed flow conditions to those in physiological flow or stagnant conditions. CFD analysis revealed the generation of disturbed flow within the model, pinpointing the specific location in the channel where the effects of disturbed flow were observed. High-content screening, a single-cell morphological profile assessment, demonstrated that HUVECs in the disturbed flow area exhibited random orientation, and morphological features were significantly distinct compared to cells in the physiological flow or stagnant condition after a two days of flow exposure. Furthermore, HUVECs exposed to disturbed flow underwent extensive remodeling of the adherens junctions and expressed higher levels of endothelial cell activation markers compared to other hemodynamic conditions. In conclusion, our in vitro bypass flow model provides a robust platform for investigating the associations between disturbed flow pattern and vascular diseases.

HnRNPA1 Prevents Endothelial-to-mesenchymal Transition-induced VSMC Activation and Neointimal Hyperplasia in Vein Grafts

Endothelial-to-mesenchymal transition (EndoMT) is associated with neointimal hyperplasia and vein graft failure, and heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) has emerged as a major modulator of EMT. We aimed to investigate the functional consequence of EndoMT in neointimal hyperplasia and the precise role of hnRNPA1 in the regulation of EndoMT and neointimal hyperplasia. We investigated the spatial and temporal distribution characteristics of EndoMT cells in a mouse model of vein graft transplantation. In vitro, we studied the interaction between EndoMT cells and VSMCs, and the underlying mechanism was investigated by cytokine antibody assays. In cultured HUVECs, we studied the effect of hnRNPA1 on EndoMT and the cellular interactions by using siRNA-mediated knockdown and adenovirus-mediated overexpression. We further investigated the role of hnRNPA1 in EndoMT and neointimal hyperplasia in vivo with an AAV-mediated EC-specific hnRNPA1 overexpression murine model. We demonstrated the presence of EndoMT cells during the initial stage of neointimal formation, and that EndoMT cells promoted the proliferation and migration of VSMCs in vitro. Mechanistic studies revealed that EndoMT cells express and secrete a higher level of PDGF-B. Furthermore, we found a regulatory role for hnRNPA1 in EndoMT in vitro and in vivo. Similarly, we found that hnRNPA1 overexpression in ECs reduced the expression and secretion of PDGF-B during EndoMT, effectively inhibiting EndoMT cell-mediated activation of VSMCs in vitro and neointimal formation in vivo. Taken together, these findings indicate that EndoMT cells can activate VSMCs through a paracrine mechanism mediated by hnRNPA1 and lead to neointimal hyperplasia.

FGL2/FcγRIIB Signalling Mediates Arterial Shear Stress-Mediated Endothelial Cell Apoptosis: Implications for Coronary Artery Bypass Vein Graft Pathogenesis

The sudden exposure of venous endothelial cells (vECs) to arterial fluid shear stress (FSS) is thought to be a major contributor to coronary artery bypass vein graft failure (VGF). However, the effects of arterial FSS on the vEC secretome are poorly characterised. We propose that analysis of the vEC secretome may reveal potential therapeutic approaches to suppress VGF. Human umbilical vein endothelial cells (HUVECs) pre-conditioned to venous FSS (18 h; 1.5 dynes/cm2) were exposed to venous or arterial FSS (15 dynes/cm2) for 24 h. Tandem Mass Tagging proteomic analysis of the vEC secretome identified significantly increased fibroleukin (FGL2) in conditioned media from HUVECs exposed to arterial FSS. This increase was validated by Western blotting. Application of the NFκB inhibitor BAY 11-7085 (1 µM) following pre-conditioning reduced FGL2 release from vECs exposed to arterial FSS. Exposure of vECs to arterial FSS increased apoptosis, measured by active cleaved caspase-3 (CC3) immunocytochemistry, which was likewise elevated in HUVECs treated with recombinant FGL2 (20 ng/mL) for 24 h under static conditions. To determine the mechanism of FGL2-induced apoptosis, HUVECs were pre-treated with a blocking antibody to FcγRIIB, a receptor FGL2 is proposed to interact with, which reduced CC3 levels. In conclusion, our findings indicate that the exposure of vECs to arterial FSS results in increased release of FGL2 via NFκB signalling, which promotes endothelial apoptosis via FcγRIIB signalling. Therefore, the inhibition of FGL2/FcγRIIB signalling may provide a novel approach to reduce arterial FSS-induced vEC apoptosis in vein grafts and suppress VGF.

Identification of a subpopulation of highly adherent endothelial cells for seeding synthetic vascular grafts

OBJECTIVE

There is an unmet clinical need for alternatives to autologous vessel grafts. Small-diameter (<6 mm) synthetic vascular grafts are not suitable because of unacceptable patency rates. This mainly occurs due to the lack of an endothelial cell (EC) monolayer to prevent platelet activation, thrombosis, and intimal hyperplasia. There are no reliable methods to endothelialize small-diameter grafts because most seeded ECs are lost due to exposure to fluid shear stress after implantation. The goal of this work is to determine if EC loss is a random process or if it is possible to predict which cells are more likely to remain adherent.

METHODS

In initial studies, we sorted ECs using fluid shear stress and identified a subpopulation of ECs that are more likely to resist detachment. We use RNA sequencing to examine gene expression of adherent ECs compared with the whole population. Using fluorescence activated cell sorting, we sorted ECs based on the expression level of a candidate marker and studied their retention in small-diameter vascular grafts in vitro.

RESULTS

Transcriptomic analysis revealed that fibronectin leucine rich transmembrane protein 2 (FLRT2), encoding protein FLRT2, is downregulated in the ECs that are more likely to resist detachment. When seeded onto vascular grafts and exposed to shear stress, ECs expressing low levels of FLRT2 exhibit 59.2% ± 7.4% retention compared with 24.5% ± 6.1% retention for the remainder of the EC population.

CONCLUSIONS

For the first time, we show EC detachment is not an entirely random process. This provides validation for the concept that we can seed small-diameter vascular grafts only with highly adherent ECs to maintain a stable endothelium and improve graft patency rates.

Saphenous Vein Graft Pseudoaneurysm Treated With Covered Stenting

Saphenous vein graft (SVG) pseudoaneurysms are an infrequent, but life-threatening complication of coronary artery bypass grafting (CABG) surgery if left untreated. Here, we discuss the case of a 77-year-old patient, with a prior history of CABG and transcatheter aortic valve implantation (TAVI), who was incidentally found on computed tomography angiography (CTA) to have a pseudoaneurysm of his SVG with an initial chief complaint of dizziness. Despite increasing reports of SVG pseudoaneurysm, there is no consensus on definitive treatment. Due to the high mortality risk of this patient with surgical intervention, a minimally invasive percutaneous coronary intervention was performed. The patient was effectively treated with two overlapping Viabahn-covered stents, which completely excluded the pseudoaneurysm. Follow-up imaging at two months showed two well-positioned overlapping self-expanding stents with total occlusion of the pseudoaneurysm.

Elevated Shear Stress Modulates Heterogenous Cellular Subpopulations to Induce Vascular Remodeling

Rationale: Elevated shear stress (ESS) induces vascular remodeling in veins exposed to arterial blood flow, which can lead to arteriovenous (AV) fistula failure. The molecular mechanisms driving remodeling have not been comprehensively examined with a single-cell resolution before. Objective: Using an in vivo animal mode, single-cell RNA sequencing, and histopathology, we precisely manipulate blood flow to comprehensively characterize all cell subpopulations important during vascular remodeling. Methods: AV loops were created in saphenous vessels of rats using a contralateral saphenous vein interposition graft to promote ESS. Saphenous veins with no elevated shear stress (NSS) were anastomosed as controls. Findings: ESS promoted transcriptional homogeneity, and NSS promoted considerable heterogeneity. Specifically, ESS endothelial cells (ECs) showed a more homogeneous transcriptional response promoting angiogenesis and upregulating endothelial-to-mesenchymal transition inhibiting genes (Klf2). NSS ECs upregulated antiproliferation genes such as Cav1, Cst3, and Btg1. In macrophages, ESS promoted a large homogeneous subpopulation, creating a mechanically activated, proinflammatory and thus proangiogenic myeloid phenotype, whereas NSS myeloid cells expressed the anti-inflammatory and antiangiogenetic marker Mrc1. Conclusion: ESS activates unified gene expression profiles to induce adaption of the vessel wall to hemodynamic alterations. Targeted depletion of the identified cellular subpopulations may lead to novel therapies to prevent excessive venous remodeling, intimal hyperplasia, and AV fistula failure.

Surgical Coronary Revascularization in Patients With Underlying Atrial Fibrillation: State-of-the-Art Review

The number of individuals referred for coronary artery bypass grafting (CABG) with preoperative atrial fibrillation (AF) is reported to be 8% to 20%. Atrial fibrillation is a known marker of high-risk patients as it was repeatedly found to negatively influence survival. Therefore, when performing surgical revascularization, consideration should be given to the concomitant treatment of the arrhythmia, the clinical consequences of the arrhythmia itself, and the selection of adequate surgical techniques. This state-of-the-art review aimed to provide a comprehensive analysis of the current understanding of, advancements in, and optimal strategies for CABG in patients with underlying AF. The following topics are considered: stroke prevention, prophylaxis and occurrence of postoperative AF, the role of surgical ablation and left atrial appendage occlusion, and an on-pump vs off-pump strategy. Multiple acute complications can occur in patients with preexisting AF undergoing CABG, each of which can have a significant effect on patient outcomes. Long-term results in these patients and the future perspectives of this scientific area were also addressed. Preoperative arrhythmia should always be considered for surgical ablation because such an approach improves prognosis without increasing perioperative risk. While planning a revascularization strategy, it should be noted that although off-pump coronary artery bypass provides better short-term outcomes, conventional on-pump approach may be beneficial at long-term follow-up. By collecting the current evidence, addressing knowledge gaps, and offering practical recommendations, this state-of-the-art review serves as a valuable resource for clinicians involved in the management of patients with AF undergoing CABG, ultimately contributing to improved outcomes and enhanced patient care.

Risk factors for infection at the saphenous vein harvest site after coronary artery bypass grafting surgery: a retrospective cohort study

INTRODUCTION

Surgical site infection after saphenous vein harvest is common, with reported leg wound infection rates ranging from 2 to 24%. There have been few investigations into sex-related differences in complication rates. Moreover, varied effects of smoking have been reported. The aim of this study was to investigate risk factors such as gender and smoking, associated with surgical site infection after vein graft harvesting in coronary artery bypass grafting surgery.

METHODS

We included 2,188 consecutive patients who underwent coronary artery bypass grafting surgery with at least one vein graft at our centre from 2009 to 2018. All patients were followed up postoperatively. Risk factors for leg wound infection requiring antibiotic treatment and surgical revision were analysed using logistic regression analysis.

RESULTS

In total, 374 patients (17.1%) received antibiotic treatment and 154 (7.0%) underwent surgical revision for leg wound infection at the harvest site. Female sex, high body mass index, diabetes mellitus, longer operation time, peripheral vascular disease and direct oral anticoagulants were independently associated with any leg wound infection at the harvest site. Among surgically revised patients, female sex and insulin or oral treatment for diabetes mellitus as well as longer operation time were independent risk factors. Smoking was not associated with leg wound infection.

CONCLUSION

Female sex is associated with increased risk of leg wound infection. The underlying mechanism is unknown. In the current population, previous or current smoking was not associated with an increased risk of leg wound infection.

An Obligatory Role of Perivascular Adipose Tissue in Improved Saphenous Vein Graft Patency in Coronary Artery Bypass Grafting

The gold standard graft for coronary artery bypass grafting (CABG) is the internal thoracic artery (ITA), and the second recommendation is the radial artery. However, complete revascularization with arterial grafts alone is often difficult, and the saphenous vein (SV) is the most commonly used autologous graft for CABG, because it is easier to use without restriction for the length of the graft. On the other hand, the patency of SV grafts (SVGs) is poor compared with that of arterial grafts. The SVG is conventionally harvested as a distended conduit with surrounding tissue removed, a procedure that may cause vascular damage. A no-touch technique of SVG harvesting has been reported to result in improved long-term patency in CABG comparable to that when using the ITA for grafting. Possible reasons for the excellent long-term patency of no-touch SVGs are the physical support provided by preserved surrounding perivascular adipose tissue, preservation of the vascular wall structure including the vasa vasorum, and production of adipocyte-derived factors. In this review, we discuss recent strategies aimed at improving the performance of SVGs, including no-touch harvesting, minimally invasive harvesting and mechanical support using external stents.

A Comparison of Three-Layer and Single-Layer Small Vascular Grafts Manufactured via the Roto-Evaporation Method

This study used the roto-evaporation technique to engineer a 6 mm three-layer polyurethane vascular graft (TVG) that mimics the architecture of human coronary artery native vessels. Two segmented polyurethanes were synthesized using lysine (SPUUK) and ascorbic acid (SPUAA), and the resulting materials were used to create the intima and adventitia layers, respectively. In contrast, the media layer of the TVG was composed of a commercially available polyurethane, Pearlbond 703 EXP. For comparison purposes, single-layer vascular grafts (SVGs) from individual polyurethanes and a polyurethane blend (MVG) were made and tested similarly and evaluated according to the ISO 7198 standard. The TVG exhibited the highest circumferential tensile strength and longitudinal forces compared to single-layer vascular grafts of lower thicknesses made from the same polyurethanes. The TVG also showed higher suture and burst strength values than native vessels. The TVG withstood up to 2087 ± 139 mmHg and exhibited a compliance of 0.15 ± 0.1%/100 mmHg, while SPUUK SVGs showed a compliance of 5.21 ± 1.29%/100 mmHg, akin to coronary arteries but superior to the saphenous vein. An indirect cytocompatibility test using the MDA-MB-231 cell line showed 90 to 100% viability for all polyurethanes, surpassing the minimum 70% threshold needed for biomaterials deemed cytocompatibility. Despite the non-cytotoxic nature of the polyurethane extracts when grown directly on the surface, they displayed poor fibroblast adhesion, except for SPUUK. All vascular grafts showed hemolysis values under the permissible limit of 5% and longer coagulation times.

Trigeminal neuralgia caused by venous compression: a comprehensive literature review

Trigeminal neuralgia (TN), a severe facial pain condition, is often treated with microvascular decompression (MVD). While MVD is effective for arterial neurovascular compression, its efficacy in cases of venous compression and the intraoperative management of such cases remain areas of debate. This review aimed to analyze the intraoperative management strategies for offending veins during MVD and evaluate the outcomes of these procedures in cases of TN with purely venous compression. An extensive review of studies reporting on the intraoperative handling of veins and the surgical outcomes of MVD in purely venous compression cases was conducted. Fifteen full-text studies were included, encompassing a total of 600 patients. Notably, 82.33% of these patients achieved a Barrow Neurological Institute (BNI) I pain score, with follow-up periods ranging from 3 months to 12 years. MVD is a viable and effective treatment option for TN in cases of venous compression, with a significant proportion of patients experiencing substantial pain relief.

Hemodynamics and Wall Mechanics of Vascular Graft Failure

Blood vessels are subjected to complex biomechanical loads, primarily from pressure-driven blood flow. Abnormal loading associated with vascular grafts, arising from altered hemodynamics or wall mechanics, can cause acute and progressive vascular failure and end-organ dysfunction. Perturbations to mechanobiological stimuli experienced by vascular cells contribute to remodeling of the vascular wall via activation of mechanosensitive signaling pathways and subsequent changes in gene expression and associated turnover of cells and extracellular matrix. In this review, we outline experimental and computational tools used to quantify metrics of biomechanical loading in vascular grafts and highlight those that show potential in predicting graft failure for diverse disease contexts. We include metrics derived from both fluid and solid mechanics that drive feedback loops between mechanobiological processes and changes in the biomechanical state that govern the natural history of vascular grafts. As illustrative examples, we consider application-specific coronary artery bypass grafts, peripheral vascular grafts, and tissue-engineered vascular grafts for congenital heart surgery as each of these involves unique circulatory environments, loading magnitudes, and graft materials.

Pharmaceutical Manipulation of Mitochondrial F0F1-ATP Synthase Enables Imaging and Protection of Myocardial Ischemia/Reperfusion Injury Through Stress-induced Selective Enrichment

To rescue ischemic myocardium from progressing to myocardial infarction, timely identification of the infarct size and reperfusion is crucial. However, fast and accurate identification, as well as the targeted protection of injured cardiomyocytes following ischemia/reperfusion (I/R) injury, remain significantly challenging. Here, a near infrared heptamethine dye IR-780 is shown that has the potential to quickly monitor the area at risk following I/R injury by selectively entering the cardiomyocytes of the at-risk heart tissues. Preconditioning with IR-780 or timely IR-780 administration before reperfusion significantly protects the heart from ischemia and oxidative stress-induced cell death, myocardial remodeling, and heart failure in both rat and pig models. Furthermore, IR-780 can directly bind to F0F1-ATP synthase of cardiomyocytes, rapidly decrease the mitochondrial membrane potential, and subsequently slow down the mitochondrial energy metabolism, which induces the mitochondria into a "quiescent state" and results in mitochondrial permeability transition pore inhibition by preventing mitochondrial calcium overload. Collectively, the findings show the feasibility of IR-780-based imaging and protection strategy for I/R injury in a preclinical context and indicate that moderate mitochondrial function depression is a mode of action that can be targeted in the development of cardioprotective reagents.

Realtime assessment of vascular occlusion and reperfusion in animal models of intraoperative imaging - a pilot study

Objectives

Intraoperative monitoring of blood flow (BF) remains vital to guiding surgical decisions. Here, we report the use of SurgeON™ Blood Flow Monitor (BFM), a prototype system that attaches to surgical microscopes and implements laser speckle contrast imaging (LSCI) to noninvasively obtain and present vascular BF information in real-time within the microscope's eyepiece.

Methods

The ability of SurgeON BFM to monitor BF status during reversible vascular occlusion procedures was investigated in two large animal models: occlusion of saphenous veins in six NZW rabbit hindlimbs and clipping of middle cerebral artery (MCA) branches in four Dorset sheep brain hemispheres. SurgeON BFM acquired, presented, and stored LSCI-based blood flow velocity index (BFVi) data and performed indocyanine green video angiography (ICG-VA) for corroboration.

Results

Stored BFVi data were analyzed for each phase: pre-occlusion (baseline), with the vessel occluded (occlusion), and after reversal of occlusion (re-perfusion). In saphenous veins, BFVi relative to baseline reduced to 5.2±3.7 % during occlusion and returned to 102.9±14.9 % during re-perfusion. Unlike ICG-VA, SurgeON BFM was able to monitor reduced BFVi and characterize re-perfusion robustly during five serial occlusion procedures conducted 2-5 min apart on the same vessel. Across four sheep MCA vessels, BFVi reduced to 18.6±7.7 % and returned to 120.1±27.8 % of baseline during occlusion and re-perfusion phases, respectively.

Conclusions

SurgeON BFM can noninvasively monitor vascular occlusion status and provide intuitive visualization of BF information in real-time to an operating surgeon. This technology may find application in vascular, plastic, and neurovascular surgery.

Consensus statement-graft treatment in cardiovascular bypass graft surgery

Coronary artery bypass grafting (CABG) is and continues to be the preferred revascularization strategy in patients with multivessel disease. Graft selection has been shown to influence the outcomes following CABG. During the last almost 60 years saphenous vein grafts (SVG) together with the internal mammary artery have become the standard of care for patients undergoing CABG surgery. While there is little doubt about the benefits, the patency rates are constantly under debate. Despite its acknowledged limitations in terms of long-term patency due to intimal hyperplasia, the saphenous vein is still the most often used graft. Although reendothelialization occurs early postoperatively, the process of intimal hyperplasia remains irreversible. This is due in part to the persistence of high shear forces, the chronic localized inflammatory response, and the partial dysfunctionality of the regenerated endothelium. "No-Touch" harvesting techniques, specific storage solutions, pressure controlled graft flushing and external stenting are important and established methods aiming to overcome the process of intimal hyperplasia at different time levels. Still despite the known evidence these methods are not standard everywhere. The use of arterial grafts is another strategy to address the inferior SVG patency rates and to perform CABG with total arterial revascularization. Composite grafting, pharmacological agents as well as latest minimal invasive techniques aim in the same direction. To give guide and set standards all graft related topics for CABG are presented in this expert opinion document on graft treatment.

Outcomes after surgical revascularization in diabetic patients

OBJECTIVES

Patients with diabetes mellitus (DM) undergoing coronary artery bypass grafting (CABG) have been repeatedly demonstrated to have worse clinical outcomes compared to patients without DM. The objective of this study was to evaluate the impact of DM on 1-year clinical outcomes after isolated CABG.

METHODS

The European DuraGraft registry included 1130 patients (44.6%) with and 1402 (55.4%) patients without DM undergoing isolated CABG. Intra-operatively, all free venous and arterial grafts were treated with an endothelial damage inhibitor. Primary end point in this analysis was the incidence of a major adverse cardiac event (MACE), a composite of all-cause death, repeat revascularization or myocardial infarction at 1 year post-CABG. To balance between differences in baseline characteristics (n = 1072 patients in each group), propensity score matching was used. Multivariable Cox proportional hazards regression was performed to identify independent predictors of MACE.

RESULTS

Diabetic patients had a higher cardiovascular risk profile and EuroSCORE II with overall more comorbidities. Patients were comparable in regard to surgical techniques and completeness of revascularization. At 1 year, diabetics had a higher MACE rate {7.9% vs 5.5%, hazard ratio (HR) 1.43 [95% confidence interval (CI) 1.05-1.95], P = 0.02}, driven by increased rates of death [5.6% vs 3.5%, HR 1.61 (95% CI 1.10-2.36), P = 0.01] and myocardial infarction [2.8% vs 1.4%, HR 1.99 (95% CI 1.12-3.53) P = 0.02]. Following propensity matching, no statistically significant difference was found for MACE [7.1% vs 5.7%, HR 1.23 (95% CI 0.87-1.74) P = 0.23] or its components. Age, critical operative state, extracardiac arteriopathy, ejection fraction ≤50% and left main disease but not DM were identified as independent predictors for MACE.

CONCLUSIONS

In this study, 1-year outcomes in diabetics undergoing isolated CABG were comparable to patients without DM.

Identification of important genes related to HVSMC proliferation and migration in graft restenosis based on WGCNA

The great saphenous vein is the most commonly used vessel for coronary artery bypass grafting (CABG), but its use has been associated with a high restenosis rate at 10-year follow-up. This study sought to determine the key genes associated with vein graft restenosis that could serve as novel therapeutic targets. A total of 3075 upregulated and 1404 downregulated genes were identified after transcriptome sequencing of three pairs of restenosed vein grafts and intraoperative spare great saphenous veins. Weighted gene co-expression network analysis showed that the floralwhite module had the highest correlation with vein graft restenosis. The intersection of the floralwhite module gene set and the upregulated gene set contained 615 upregulated genes strongly correlated with vein graft restenosis. Protein-protein interaction network analysis identified six hub genes (ITGAM, PTPRC, TLR4, TYROBP, ITGB2 and CD4), which were obtained using the STRING database and CytoHubba. Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses showed that the common hub genes were mainly involved in the composition of the cell membrane; in biological processes such as neutrophil degranulation, receptor binding and intercellular adhesion, innate immune deficiency; and other signaling pathways. Finally, ITGB2 was selected as the target gene, and its expression was verified in tissues. The results showed that ITGB2 was significantly overexpressed in occluded vein grafts. To study the function of ITGB2 in HVSMCs, primary HVSMCs were cultured and successfully identified. EdU incorporation, wound healing and transwell assays showed that ITGB2 silencing significantly inhibited the proliferation and migration of HVSMCs stimulated by PDGF-BB. Overall, our study provides a basis for future studies on preventing restenosis following CABG.

Lymphedema after saphenous harvesting for coronary artery bypass surgery: case report and literature review

Different causes have been described for secondary lymphedema as reported in this article. A 75-year-old man was diagnosed with lymphedema about one decade after saphenous harvesting for coronary artery bypass surgery. It took two years for him to find out his diagnosis and receive the proper treatment. After standard complete decongestive therapy, his volume and pain decreased and his quality of life was improved, especially its physical aspect. It is important to recognize the possibility of lymphedema development after saphenous harvesting among patients undergoing coronary artery bypass surgery to prevent significant disturbance of quality of life with timely management.

Perivascular CLICK-gelatin delivery of thrombospondin-2 small interfering RNA decreases development of intimal hyperplasia after arterial injury

Bypass graft failure occurs in 20%-50% of coronary and lower extremity bypasses within the first-year due to intimal hyperplasia (IH). TSP-2 is a key regulatory protein that has been implicated in the development of IH following vessel injury. In this study, we developed a biodegradable CLICK-chemistry gelatin-based hydrogel to achieve sustained perivascular delivery of TSP-2 siRNA to rat carotid arteries following endothelial denudation injury. At 21 days, perivascular application of TSP-2 siRNA embedded hydrogels significantly downregulated TSP-2 gene expression, cellular proliferation, as well as other associated mediators of IH including MMP-9 and VEGF-R2, ultimately resulting in a significant decrease in IH. Our data illustrates the ability of perivascular CLICK-gelatin delivery of TSP-2 siRNA to mitigate IH following arterial injury.

Angiographic and Clinical Outcomes of Various Techniques of Intracranial-to-Intracranial Bypass for Complex Cases with a Review of Pertinent Literature and Illustrated Cases

BACKGROUND

We sought to determine the utility of intracranial-to-intracranial bypass (IIB) surgery and the available bypass options for complex cases.

METHODS

A total of 18 IIB cases were included. Each case was classified as IIB with or without an interposition graft. The clinical and angiographic status were evaluated pre- and postoperatively and at the last follow-up. Angiographic images were analyzed and reconstructed schematically. Postoperative angiography was used to measure the bypass patency and the presence of postoperative cerebral infarction. The recipient artery occlusion time for each bypass was measured.

RESULTS

Of the 18 patients, 14 had presented with a complex intracranial aneurysm (IA), 1 with vertebrobasilar dolichoectasia, and 3 with intracranial arterial steno-occlusive disease. Ten patients had an incidentally discovered IA. Seven patients had presented with neurological deficits due to ischemia or aneurysmal mass effects. Of the 18 cases, 10 were IIBs with an interposition graft, including 4 cases of superficial temporal artery and 6 of radial artery graft bypass, and 8 were IIBs with a noninterposition graft, including 3 cases of in situ bypass, 1 case of reanastomosis, and 4 cases of reimplantation. The pre- and postoperative modified Rankin scale score did not change or improve, and all the bypasses were patent. No patient had died during the mean follow-up period of 50.0 months. The mean occlusion time of the recipient artery was 59.5 minutes. A total of 8 patients experienced postoperative cerebral infarction but all had almost recovered at discharge.

CONCLUSIONS

With proper selection of the IIB type, IIB can be a suitable treatment option for some patients with complex IAs and intracranial arterial steno-occlusive disease when extracranial-to-intracranial bypass is not feasible.

Coronary Artery Bypass Surgery: Evidence-Based Practice

Coronary artery bypass graft (CABG) surgery remains a pivotal cornerstone, offering established symptomatic alleviation and prognostic advantages for patients grappling with complex multivessel and left main coronary artery diseases. Despite the lucid guidance laid out by contemporary guidelines regarding the choice between CABG and percutaneous coronary intervention (PCI), a notable hesitation persists among certain patients, characterized by psychological reservations, knowledge gaps, or individual beliefs that sway their inclination toward surgical intervention. This comprehensive review critically synthesizes the prevailing guidelines, modern practices, and outcomes pertaining to CABG surgery, delving into an array of techniques and advancements poised to enhance both short-term and enduring surgical outcomes. The exploration encompasses advances in on-pump and off-pump procedures, conduit selection strategies encompassing the bilateral utilization of internal mammary artery and radial artery conduits, meticulous graft evaluation methodologies, and the panorama of minimally invasive approaches, including those assisted by robotic technology. Furthermore, the review navigates the terrain of hybrid coronary revascularization, shedding light on the pivotal roles of shared decision-making and the heart team in shaping treatment pathways. As a comprehensive compendium, this review not only navigates the intricate landscape of CABG surgery but also aligns it with contemporary practices, envisioning its trajectory within the evolving currents of healthcare dynamics.

The Evaluation and Management of Coronary Artery Disease in the Lung Transplant Patient

Lung transplantation can greatly improve quality of life and extend survival in those with end-stage lung disease. In order to derive the maximal benefit from such a procedure, patients must be carefully selected and be otherwise healthy enough to survive a high-risk surgery and sometimes prolonged immunosuppressive therapy following surgery. Patients therefore must be critically assessed prior to being listed for transplantation with close attention paid towards assessment of cardiovascular health and operative risk. One of the biggest dictators of this is coronary artery disease. In this review article, we discuss the assessment and management of coronary artery disease in the potential lung transplant candidate.

Effect of specialized pro-resolving lipid mediators in the regulation of vascular tone and inflammation in human saphenous vein

Specialized pro-resolving lipid mediators (SPMs), derived from polyunsaturated fatty acids are important mediators in the resolution of inflammation. Recent studies have focused on the effects of SPMs in cardiovascular health and diseases. However, little is known about the effect SPMs on human vascular tone. Therefore, in this study it is aimed to investigate the effect of various SPMs including resolvin D- and E-series, maresin-1 (MaR1) and lipoxin-A4 (LxA4) on the vascular tone of human isolated saphenous vein (SV) preparations under inflammatory conditions. In addition, we aimed to evaluate the effects of SPMs on the release of pro-inflammatory mediators, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF- α) from human SV. Pretreatment of isolated of human SV with resolvin E1 (RvE1), resolvin D1 (RvD1) and MaR1 (100 nM, 18 h) significantly reduced the contractile responses to thromboxane A2 mimetic, U46619 whereas pretreatment with LxA4 and RvD2 (100 nM, 18 h) had no significant effect on the vascular tone of SV. Moreover, RvE1, RvD1 and MaR1 but not LxA4 and RvD2 (100 nM, 18 h) pretreatment diminished the release of MCP-1 and TNF-α from SV. In conclusion, our findings suggest that pre-treatment with RvE1, RvD1, and MaR1 could have potential benefits in decreasing graft vasospasm and vascular inflammation in SV.

Endothelial damage inhibitor preserves the integrity of venous endothelial cells from patients undergoing coronary bypass surgery

OBJECTIVES

Despite the success of coronary artery bypass graft (CABG) surgery using autologous saphenous vein grafts (SVGs), nearly 50% of patients experience vein graft disease within 10 years of surgery. One contributing factor to early vein graft disease is endothelial damage during short-term storage of SVGs in inappropriate solutions. Our aim was to evaluate the effects of a novel endothelial damage inhibitor (EDI) on SVGs from patients undergoing elective CABG surgery and on venous endothelial cells (VECs) derived from these SVGs.

METHODS

SVGs from 11 patients participating in an ongoing clinical registry (NCT02922088) were included in this study, and incubated with both full electrolyte solution (FES) or EDI for 1 h and then examined histologically. In 8 of 11 patients, VECs were isolated from untreated grafts, incubated with both FES and EDI for 2 h under hypothermic stress conditions and then analysed for activation of an inflammatory phenotype, cell damage and cytotoxicity, as well as endothelial integrity and barrier function.

RESULTS

The EDI was superior to FES in protecting the endothelium in SVGs (74 ± 8% versus 56 ± 8%, P < 0.001). Besides confirming that the EDI prevents apoptosis in SVG-derived VECs, we also showed that the EDI temporarily reduces adherens junctions in VECs while protecting focal adhesions compared to FES.

CONCLUSIONS

The EDI protects the connectivity and function of the SVG endothelium. Our data suggest that the EDI can preserve focal adhesions in VECs during short-term storage after graft harvesting. This might explain the superiority of the EDI in maintaining most of the endothelium in venous CABG surgery conduits.

Pain-related fear among adult patients undergoing open-heart surgery: an interpretative phenomenological analysis

BACKGROUND

One of the sources of anxiety and fear among patients undergoing open-heart surgery is the possibility of experiencing pain, such as sternotomy-related chest pain. Giving them the chance to express their feelings about the potential pain may be effective in reducing their anxiety and may support their coping strategies.

OBJECTIVES

To examine pain-related fear among patients undergoing open-heart surgery and to understand the underlying reasons of their fears.

METHODS

A qualitative interview based on Heidegger's interpretative phenomenological approach was conducted adhering to the COREQ guidelines. Sixteen patients who were undergoing open-heart surgery in the following day were interviewed at the cardiovascular surgery ward of a university hospital. The organization and mapping of the qualitative data was done by using ATLAS.ti 8.0.

RESULTS

The patients who were afraid of experiencing pain after surgery seemed to be more concerned about open-heart surgery itself (such as pain from sternotomy and chest tubes) and the possibility of prolongation of postoperative pain. To cope with these fears, the patients employed a variety of social and self-coping strategies. Trusting the healthcare team, having a high pain tolerance, and having personal thoughts that take precedence over pain-related fear were the key factors explaining not being afraid of experiencing pain.

CONCLUSIONS

This study provides a deeper understanding of the underlying reasons and the needs of patients in controlling their pain-related fears before open-heart surgery. Trusting the healthcare professionals is one of the main factors for patients to control their pain-related fears. To develop a supportive sense of trust and to help patients in controlling their pain-related fears, surgical nurses must dedicate enough time for understanding patients' concerns while planning their nursing care plans. Future studies may focus on exploring the role of nursing interventions and multidisciplinary team approaches on the management of preoperative pain-related fear.

External Stenting for Saphenous Vein Grafts in Coronary Surgery: A Systematic Review and Meta-Analysis

The external stenting of saphenous vein grafts (SVGs) during coronary artery bypass grafting (CABG) has been proven to reduce intimal hyperplasia (IH) in animal models, paving the way for human randomized controlled trials (RCTs) to be conducted. Herein, we performed a study-level meta-analysis to assess the impact of the Venous External SupporT (VEST) device, an external stent, on the outcomes of SVGs. A systematic search was conducted to identify all RCTs comparing VEST-stented to non-stented SVGs in patients undergoing CABG. The primary outcome was graft occlusion. The main secondary outcomes were repeat revascularization, SVG IH area, and intimal-medial thickness. Two RCTs totaling 407 patients were included. At a mean follow-up of 1.5 years, there was no difference in graft occlusion between groups (incidence rate ratio: 1.11; 95% confidence interval (CI): 0.80-1.53). The rate of repeat revascularization was also similar (odds ratio: 0.66; 95% CI: 0.27-1.64). The IH area (standardized mean difference (SMD): -0.45; 95% CI: -0.79 to -0.10) and intimal-medial thickness (SMD: -0.50; 95% CI: -0.90 to -0.10) were significantly reduced in the VEST group. Our findings show that significant reductions in the IH area and the intimal-medial thickness in VEST-stented SVGs do not currently translate into a lesser need for repeat revascularization or less graft occlusion events compared to non-stented SVGs at 1.5 years after CABG.

Survival Benefit of Multiple Arterial Revascularization With and Without Supplementary Saphenous Vein Graft

Background It is unknown if the presence of saphenous vein grafting (SVG) adversely affects late survival following coronary surgery with multiple arterial grafting (MAG) versus single arterial grafting. Methods and Results A retrospective, observational, multicenter cohort study from 2001 to 2020 was conducted using the Australian and New Zealand Society of Cardiac and Thoracic Surgeons Database linked to the National Death Index. Patients undergoing primary isolated coronary artery bypass grafting with ≥2 grafts were included, and exclusions were patients aged <18 years, reoperations, concomitant or previous cardiac surgery, and the absence of arterial grafting. Demographics, comorbidities, medication, and operative configurations were propensity score matched between cohorts. The primary outcome was all-cause late death. Of 59 689 eligible patients, 35 113 were MAG (58.8%), and 24 576 were single arterial grafting (41.2%). Of the MAG cohort, 17 055 (48.6%) patients did not receive supplementary SVG (total arterial revascularization). Matching separately generated 22 764 patient pairs for MAG versus single arterial grafting, and 11 137 patient pairs for MAG with total arterial revascularization versus MAG with ≥1 supplementary vein grafts. At a median follow-up duration of 5.0 years postoperatively, the mortality rate was significantly lower for MAG than single arterial grafting (hazard ratio [HR], 0.79 [95% CI, 0.76-0.83]; P<0.001). The stratified MAG analysis found that MAG with total arterial revascularization had a lower risk of late death (HR, 0.85 [95% CI, 0.80-0.91]; P<0.001) compared with MAG with ≥1 supplementary vein grafts. Sensitivity analyses produced consistent outcomes as the primary analysis. Following adjustment for the presence of SVG in the Cox model, the survival advantage of incremental number of arteries was lost. Conclusions Multiple arterial grafting has significantly improved long-term survival compared with single arterial grafting. A further incremental survival benefit exists when no SVG is used.

The VEST External Support for Saphenous Vein Grafts in Coronary Surgery: A Review of Randomized Clinical Trials

Saphenous vein grafts (SVGs) are the most frequently used conduits in coronary artery bypass grafting (CABG), but their higher rate of occlusion compared to arterial conduits remains a concern. Previous studies have shown that SVG failure is mainly driven by intimal hyperplasia, an adaptative response to higher pressures of the arterial circulation. The VESTTM device (Vascular Graft Solutions, Tel Aviv, Israel), an external support designed to mitigate intimal hyperplasia in SVGs, has been tested in few clinical trials (RCTs). Herein, we descriptively evaluated the randomized evidence on the VEST device.

Antiplatelet Resistance in Patients Who Underwent Coronary Artery Bypass Grafting: A Systematic Review and Meta-Analysis

Antiplatelet therapy (APT) with aspirin and a P2Y12 inhibitor is commonly given to patients who underwent coronary artery bypass grafting (CABG) to reduce thrombotic events. APT resistance, the inadequate antiplatelet effect of these drugs, is a growing concern. This review aimed to assess APT resistance prevalence in patients who underwent CABG and its impact on clinical outcomes. We conducted a comprehensive search for relevant studies published to date. The included studies measured platelet function through laboratory assays and reported on clinical outcomes in patients who underwent CABG. The primary outcomes were major adverse cardiovascular events (MACEs) and mortality, whereas the secondary outcomes included acute coronary syndrome (ACS), stroke, and thromboembolic events. The meta-analysis used random-effects models, with heterogeneity assessed using the I2 statistic. The initial search identified 45 studies, with 11 meeting the inclusion criteria, involving 3,122 patients. The overall prevalence of APT resistance in patients who underwent CABG was 39%. Patients with APT resistance had significantly higher risks of MACEs and death (odds ratio [OR] 1.73, 95% confidence interval [CI] 1.06 to 2.83, p = 0.03) and postoperative myocardial infarction (OR 2.25, 95% CI 1.13 to 4.48, p = 0.02) than those without resistance. However, no significant association was found between APT resistance and stroke (OR 2.25, 95% CI 0.80 to 6.35, p = 0.12) or other thromboembolic events (OR 1.72, 95% CI 0.72 to 4.08, p = 0.22). In conclusion, APT resistance is prevalent in a significant proportion of patients who underwent CABG, increasing the risk of MACEs and postoperative myocardial infarction. These findings emphasize the need for further research to develop tailored antiplatelet strategies in this patient population.

Graft Failure After Coronary Artery Bypass Grafting and Its Association With Patient Characteristics and Clinical Events: A Pooled Individual Patient Data Analysis of Clinical Trials With Imaging Follow-Up

BACKGROUND

Graft patency is the postulated mechanism for the benefits of coronary artery bypass grafting (CABG). However, systematic graft imaging assessment after CABG is rare, and there is a lack of contemporary data on the factors associated with graft failure and on the association between graft failure and clinical events after CABG.

METHODS

We pooled individual patient data from randomized clinical trials with systematic CABG graft imaging to assess the incidence of graft failure and its association with clinical risk factors. The primary outcome was the composite of myocardial infarction or repeat revascularization occurring after CABG and before imaging. A 2-stage meta-analytic approach was used to evaluate the association between graft failure and the primary outcome. We also assessed the association between graft failure and myocardial infarction, repeat revascularization, or all-cause death occurring after imaging.

RESULTS

Seven trials were included comprising 4413 patients (mean age, 64.4±9.1 years; 777 [17.6%] women; 3636 [82.4%] men) and 13 163 grafts (8740 saphenous vein grafts and 4423 arterial grafts). The median time to imaging was 1.02 years (interquartile range [IQR], 1.00-1.03). Graft failure occurred in 1487 (33.7%) patients and in 2190 (16.6%) grafts. Age (adjusted odds ratio [aOR], 1.08 [per 10-year increment] [95% CI, 1.01-1.15]; P=0.03), female sex (aOR, 1.27 [95% CI, 1.08-1.50]; P=0.004), and smoking (aOR, 1.20 [95% CI, 1.04-1.38]; P=0.01) were independently associated with graft failure, whereas statins were associated with a protective effect (aOR, 0.74 [95% CI, 0.63-0.88]; P<0.001). Graft failure was associated with an increased risk of myocardial infarction or repeat revascularization occurring between CABG and imaging assessment (8.0% in patients with graft failure versus 1.7% in patients without graft failure; aOR, 3.98 [95% CI, 3.54-4.47]; P<0.001). Graft failure was also associated with an increased risk of myocardial infarction or repeat revascularization occurring after imaging (7.8% versus 2.0%; aOR, 2.59 [95% CI, 1.86-3.62]; P<0.001). All-cause death after imaging occurred more frequently in patients with graft failure compared with patients without graft failure (11.0% versus 2.1%; aOR, 2.79 [95% CI, 2.01-3.89]; P<0.001).

CONCLUSIONS

In contemporary practice, graft failure remains common among patients undergoing CABG and is strongly associated with adverse cardiac events.

Mechanobiology of the endothelium in vascular health and disease: in vitro shear stress models

In recent years, there has been growing evidence that vascular pathologies arise in sites experiencing an altered haemodynamic environment. Fluid shear stress (FSS) is an important contributor to vascular homeostasis and regulates endothelial cell (EC) gene expression, morphology, and behaviour through specialised mechanosensitive signalling pathways. The presence of an altered FSS profile is a pathological characteristic of many vascular diseases, with the most established example being the preferential localisation of atherosclerotic plaque development. However, the precise haemodynamic contributions to other vascular pathologies including coronary artery vein graft failure remains poorly defined. To evaluate potential novel therapeutics for the treatment of vascular diseases via targeting EC behaviour, it is important to undertake in vitro experiments using appropriate culture conditions, particularly FSS. There are a wide range of in vitro models used to study the effect of FSS on the cultured endothelium, each with the ability to generate FSS flow profiles through which the investigator can control haemodynamic parameters including flow magnitude and directionality. An important consideration for selection of an appropriate model of FSS exposure is the FSS profile that the model can generate, in comparison to the physiological and pathophysiological haemodynamic environment of the vessel of interest. A resource bringing together the haemodynamic environment characteristic of atherosclerosis pathology and the flow profiles generated by in vitro methods of applying FSS would be beneficial to researchers when selecting the appropriate model for their research. Consequently, here we summarise the widely used methods of exposing cultured endothelium to FSS, the flow profile they generate and their advantages and limitations in investigating the pathological contribution of altered FSS to vascular disease and evaluating novel therapeutic targets for the treatment and prevention of vascular disease.

Non-contrast computed tomography findings for identification of chronically occluded coronary artery bypass grafts

BACKGROUND

Detecting occlusions of coronary artery bypass grafts using non-contrast computed tomography (CT) series is understudied and underestimated.

PURPOSE

To evaluate morphological findings for the diagnosis of chronic coronary artery bypass graft occlusion on non-contrast CT and investigate performance statistics for potential use cases.

MATERIAL AND METHODS

Seventy-three patients with coronary artery bypass grafts who had CT angiography of the chest (non-contrast and arterial phases) were retrospectively included. Two readers applied pre-set morphologic findings to assess the patency of a bypass graft on non-contrast series. These findings included vessel shape (linear-band like), collapsed lumen and surgical graft marker without a visible vessel. Performance was tested using the simultaneously acquired arterial phase series as the ground truth.

RESULTS

The per-patient diagnostic accuracy for occlusion was 0.890 (95% confidence interval = 0.795-0.951). Venous grafts overall had an 88% accuracy. None of the left internal mammary artery to left anterior descending artery arterial graft occlusions were detected. The negative likelihood ratio for an occluded graft that is truly patent was 0.121, demonstrating a true post-test probability of 97% for identifying a patent graft as truly patent given a prevalence of 20% occlusion at a median 8.4 years post-surgery. Neither years post-surgery, nor number of vessels was associated with a significant decrease in reader accuracy.

CONCLUSION

Evaluation of coronary bypass grafts for chronic occlusion on non-contrast CT based off vessel morphology is feasible and accurate for venous grafts. Potential use cases include low-intermediate risk patients with chest pain or shortness of breath for whom non-contrast CT was ordered, or administration of iodine-based contrast is contraindicated.

Multiple Arterial Graft Use in Coronary Artery Bypass Surgery: Surgeon Perspective vs Practice

BACKGROUND

Despite supportive evidence and guidelines, the use of multiple arterial grafts (MAGs) in coronary artery bypass grafting remains low. We sought to determine surgeon perception of personal MAG use and compare this with actual MAG use.

METHODS

We conducted a statewide surgeon survey of MAG use, presence of a hospital MAG protocol, and barriers for MAG use, with a response rate of 78% (n = 25). Surgeon survey responses were compared with actual Society of Thoracic Surgeons patient data from January 1, 2017, to December 31, 2020 using χ2 or Fisher's exact tests.

RESULTS

Of 5299 patients who had first-time, nonemergent, isolated coronary artery bypass grafting (≥2 grafts) by responding surgeons, 16% received MAG (n = 825). MAG use in patients whose surgeons self-designated as "routine" MAG users was 21% vs 7% for "nonroutine" users. Surgeons with a hospital protocol for MAG use utilized MAG more often (18% vs 14%, P = .001). Surgeons who were unconvinced by the data on the benefits of MAGs used MAGs in 11% vs 22% in surgeons who were convinced. MAG use increased over time, particularly from before to after the survey (13.1% vs 30.5%, P < .001).

CONCLUSIONS

Although MAG use increased over time, barriers to routine use remain. In surgeons who reported routine use, only 21% of their patients received MAGs. Hospital protocols, education, and increased awareness may reduce barriers to use and encourage evidence-based clinical practice.

Unplanned postoperative catheterization during admission for coronary artery bypass grafting is neither cheap nor benign, but may rescue patients

OBJECTIVE

Literature describing outcomes of myocardial ischemia after coronary artery bypass grafting is sparse. We hypothesized these patients had more complications and incurred higher costs of care.

METHODS

Using adult cardiac surgery data and cardiac catheterization (CathPCI) data from the Virginia Cardiac Services Quality Initiative, we identified patients who underwent unplanned cardiac catheterization after coronary artery bypass grafting from 2018 to 2021. Adult cardiac surgery data were matched to CathPCI data examining earliest in-hospital catheterization. Patients not requiring catheterization served as the control group.

RESULTS

We identified 10,597 patients who underwent isolated coronary artery bypass grafting, of whom 41 of 10,597 underwent unplanned cardiac catheterization. A total of 21 of 41 patients (51%) received percutaneous coronary intervention, most commonly for non-ST-elevation myocardial infarction (n = 7, 33%) and ST-elevation myocardial infarction (n = 6, 29%). Postoperative cardiac arrest occurred in 14 patients (40%). In patients who underwent percutaneous coronary intervention, 14 (67%) had a single lesion, 4 (19%) had 2 lesions, and 3 (14%) had 3 lesions. The left anterior descending artery (38%) was the most frequently intervened upon vessel. Patients who underwent catheterization were more likely to require balloon pump support (26% vs 11%), to have prolonged ventilation (57% vs 20%), to have renal failure (17% vs 7.1%), and to undergo reintubation (37% vs 3.8%, all P < .04). There was no statistical difference in operative mortality (4.9% vs 2.3%, P = .2) or failure to rescue (4.9% vs 1.6%, P = .14). Total costs were higher in patients who underwent unplanned catheterization ($81,293 vs $37,011, P < .001).

CONCLUSIONS

Unplanned catheterization after coronary artery bypass grafting is infrequent but associated with more complications and a higher cost of care. Therefore, determination of an association with operative mortality in patients with suspected ischemia after coronary artery bypass grafting requires additional study.

Impact of Age on Endothelial Function of Saphenous Vein Grafts in Coronary Artery Bypass Grafting

BACKGROUND

An intact and functionally preserved endothelial layer in the graft is crucial for myocardial perfusion and graft patency after coronary artery bypass grafting (CABG). We hypothesized that old age is a risk factor for decreased endothelial function of bypass grafts. Thus, we investigated the impact of age in patients treated with CABG on endothelial function in saphenous vein grafts.

METHODS

We mounted the saphenous vein graft segments of CABG patients < 70 (n = 33) and ≥70 (n = 40) years of age in organ bath chambers and exposed them to potassium chloride (KCl) and phenylephrine (PE) to test the receptor-independent and -dependent contractility, followed by exposure to acetylcholine (ACh) and sodium nitroprusside (SNP) to test the endothelial-dependent and -independent relaxation.

RESULTS

The maximal contraction induced by KCl (2.3 ± 1.8 vs. 1.8 ± 2 g) was stronger in patients ≥ 70 years of age. The relative contraction induced by PE in % of KCl (167 ± 64 vs. 163 ± 59%) was similar between groups. Patients aged < 70 years showed a higher endothelial-dependent relaxation induced by acetylcholine than patients ≥ 70 years (51 ± 27 vs. 42 ± 18%). The relaxation induced by SNP was similar between both groups.

CONCLUSIONS

The endothelial function of saphenous vein bypass grafts decreases during aging. Thus, age should be considered when improving graft maintenance.

MCP-1-Loaded Poly(l-lactide-co-caprolactone) Fibrous Films Modulate Macrophage Polarization toward an Anti-inflammatory Phenotype and Improve Angiogenesis

Tissue engineering approaches such as the electrospinning technique can fabricate nanofibrous scaffolds which are widely used for small-diameter vascular grafting. However, foreign body reaction (FBR) and lack of endothelial coverage are still the main cause of graft failure after the implantation of nanofibrous scaffolds. Macrophage-targeting therapeutic strategies have the potential to address these issues. Here, we fabricate a monocyte chemotactic protein-1 (MCP-1)-loaded coaxial fibrous film with poly(l-lactide-co-ε-caprolactone) (PLCL/MCP-1). The PLCL/MCP-1 fibrous film can polarize macrophages toward anti-inflammatory M2 macrophages through the sustained release of MCP-1. Meanwhile, these specific functional polarization macrophages can mitigate FBR and promote angiogenesis during the remodeling of implanted fibrous films. These studies indicate that MCP-1-loaded PLCL fibers have a higher potential to modulate macrophage polarity, which provides a new strategy for small-diameter vascular graft designing.

Nanofibers with homogeneous heparin distribution and protracted release profile for vascular tissue engineering

In clinic, controlling acute coagulation after small-diameter vessel grafts transplantation is considered a primary problem. The combination of heparin with high anticoagulant efficiency and polyurethane fiber with good compliance is a good choice for vascular materials. However, blending water-soluble heparin with fat-soluble poly (ester-ether-urethane) urea elastomer (PEEUU) uniformly and preparing nanofibers tubular grafts with uniform morphology is a huge challenge. In this research, we have compounded PEEUU with optimized constant concentration of heparin by homogeneous emulsion blending, then spun into the hybrid PEEUU/heparin nanofibers tubular graft (H-PHNF) for replacing rats' abdominal aorta in situ for comprehensive performance evaluation. The in vitro results demonstrated that H-PHNF was of uniform microstructure, moderate wettability, matched mechanical properties, reliable cytocompatibility, and strongest ability to promote endothelial growth. Replacement of resected abdominal artery with the H-PHNF in rat showed that the graft was capable of homogeneous hybrid heparin and significantly promoted the stabilization of vascular smooth muscle cells (VSMCs) as well as stabilizing the blood microenvironment. This research demonstrates the H-PHNF with substantial patency, indicating their potential for vascular tissue engineering.

Clinical outcomes and quality of life after contemporary isolated coronary bypass grafting: a prospective cohort study

OBJECTIVES

The objective of the European Multicenter Registry to Assess Outcomes in coronary artery bypass grafting (CABG) patients (DuraGraft Registry) was to determine clinical outcomes and quality of life (QoL) after contemporary CABG that included isolated CABG and combined CABG/valve procedures, using an endothelial damage inhibitor (DuraGraft) intraoperatively for conduit preservation. Here, we report outcomes in the patient cohort undergoing isolated CABG.

METHODS

The primary outcome was the composite of all-cause death, myocardial infarction (MI), or repeat revascularization (RR) [major adverse cardiac events (MACE)] at 1 year. Secondary outcomes included the composite of all-cause death, MI, RR, or stroke [major adverse cardiac and cerebrovascular events (MACCE)], and QoL. QoL was assessed with the EuroQol-5 Dimension questionnaire. Independent risk factors for MACE at 1 year were determined using Cox regression analysis.

RESULTS

A total of 2532 patients (mean age, 67.4±9.2 years; 82.5% male) underwent isolated CABG. The median EuroScore II was 1.4 [interquartile range (IQR), 0.9-2.3]. MACE and MACCE rates at 1 year were 6.6% and 7.8%, respectively. The rates of all-cause death, MI, RR, and stroke were 4.4, 2.0, 2.2, and 1.9%, respectively. The 30-day mortality rate was 2.3%. Age, extracardiac arteriopathy, left ventricular ejection fraction less than 50%, critical operative state, and left main disease were independent risk factors for MACE. QoL index values improved from 0.84 [IQR, 0.72-0.92] at baseline to 0.92 [IQR, 0.82-1.00] at 1 year ( P <0.0001).

CONCLUSION

Contemporary European patients undergoing isolated CABG have a low 1-year clinical event rate and an improved QoL.

Prediction of Male Coronary Artery Bypass Grafting Outcomes Using Body Surface Area Weighted Left Ventricular End-diastolic Diameter: Multicenter Retrospective Cohort Study

BACKGROUND

The presence of a high left ventricular end-diastolic diameter (LVEDD) has been linked to a less favorable outcome in patients undergoing coronary artery bypass grafting (CABG) procedures. However, by taking into consideration the reference of left ventricular size and volume measurements relative to the patient's body surface area (BSA), it has been suggested that the accuracy of the predicting outcomes may be improved.

OBJECTIVE

We propose that BSA weighted LVEDD (bLVEDD) is a more accurate predictor of outcomes in patients undergoing CABG compared to simply using LVEDD alone.

METHODS

This study was a comprehensive retrospective cohort study that was conducted across multiple medical centers. The inclusion criteria for this study were patients who were admitted for treatment between October 2016 and May 2021. Only elective surgery patients were included in the study, while those undergoing emergency surgery were not considered. All participants in the study received standard care, and their clinical data were collected through the institutional registry in accordance with the guidelines set forth by the Society of Thoracic Surgeons National Adult Cardiac Database. bLVEDD was defined as LVEDD divided by BSA. The primary outcome was in-hospital all-cause mortality (30 days), and the secondary outcomes were postoperative severe adverse events, including use of extracorporeal membrane oxygenation, multiorgan failure, use of intra-aortic balloon pump, postoperative stroke, and postoperative myocardial infarction.

RESULTS

In total, 9474 patients from 5 centers under the Chinese Cardiac Surgery Registry were eligible for analysis. We found that a high LVEDD was a negative factor for male patients' mortality (odds ratio 1.44, P<.001) and secondary outcomes. For female patients, LVEDD was associated with secondary outcomes but did not reach statistical differences for morality. bLVEDD showed a strong association with postsurgery mortality (odds ratio 2.70, P<.001), and secondary outcomes changed in parallel with bLVEDD in male patients. However, bLVEDD did not reach statistical differences when fitting either mortality or severer outcomes in female patients. In male patients, the categorical bLVEDD showed high power to predict mortality (area under the curve [AUC] 0.71, P<.001) while BSA (AUC 0.62) and LVEDD (AUC 0.64) both contributed to the risk of mortality but were not as significant as bLVEDD (P<.001).

CONCLUSIONS

bLVEDD is an important predictor for male mortality in CABG, removing the bias of BSA and showing a strong capability to accurately predict mortality outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02400125; https://clinicaltrials.gov/ct2/show/NCT02400125.

Venous External Support in Coronary Artery Bypass Surgery: A Systematic Review and Meta-Analysis

OBJECTIVES

Neointimal hyperplasia and lumen irregularities are major contributors to vein graft failure and the use of VEST^(R) should prevent this. In this review, we aim to evaluate the angiographic outcomes of externally supported vein grafts.

METHODS

Medline, Embase and Cochrane Library were systematically reviewed for randomized clinical trials published by August 2022. The primary outcome was graft failure. Secondary outcomes included graft ectasia, intimal hyperplasia area and thickness, and graft non-uniformity. Odds ratios (OR) for dichotomous variables and mean difference (MD) for continuous variables with 95% confidence intervals (CI) were pooled using a fixed-effects model.

RESULTS

Three randomized controlled trials with a total of 437 patients were included with follow-up ranging from 1 to 2 years. The odds of graft failure were similar in the two groups (OR 1.22; 95%CI 0.88 to 1.71; I²=0%). Intimal hyperplasia area [MD -0.77 mm²; 95%CI -1.10 to -0.45; I²=0%] and thickness [MD -0.06 mm; 95%CI -0.08 to -0.04; I²=0%] were significantly lower in the VEST group. Fitzgibbon Patency Scale of II or III (representing angiographic conduit non-uniformity; OR 0.67; 95%CI 0.48 to 0.94; I²=0%) and graft ectasia (OR 0.53; 95%CI 0.32 to 0.88; I²=33%) were also significantly lower in the VEST group.

CONCLUSIONS

At short-term follow-up, VEST does not seem to reduce the incidence of graft failure, although it is associated with attenuation of intimal hyperplasia and non-uniformity. Longer angiographic follow-up is warranted to determine whether these positive effects might translate into a positive effect in graft failure and in long-term clinical outcomes.

Graft thrombosis after coronary artery bypass surgery and current practice for prevention

Coronary artery bypass grafting (CABG) is the most frequently performed cardiac surgery worldwide. The reported incidence of graft failure ranges between 10% and 50%, depending upon the type of conduit used. Thrombosis is the predominant mechanism of early graft failure, occurring in both arterial and vein grafts. Significant advances have been made in the field of antithrombotic therapy since the introduction of aspirin, which is regarded as the cornerstone of antithrombotic therapy for prevention of graft thrombosis. Convincing evidence now exists that dual antiplatelet therapy (DAPT), consisting of aspirin and a potent oral P2Y12 inhibitor, effectively reduces the incidence of graft failure. However, this is achieved at the expense of an increase in clinically important bleeding, underscoring the importance of balancing thrombotic risk and bleeding risk when considering antithrombotic therapy after CABG. In contrast, anticoagulant therapy has proved ineffective at reducing the occurrence of graft thrombosis, pointing to platelet aggregation as the key driver of graft thrombosis. We provide a comprehensive review of current practice for prevention of graft thrombosis and discuss potential future concepts for antithrombotic therapy including P2Y12 inhibitor monotherapy and short-term DAPT.

Patients' experiences regarding severe leg wound infection associated with coronary artery bypass grafting: A qualitative study

INTRODUCTION

Coronary artery bypass grafting (CABG) is the most common cardiac surgery throughout the world. The most commonly used graft is the saphenous vein. Wound healing complications related to saphenous vein harvesting are common, with reported surgical site infection rates ranging from 2% to 20%. Surgical site infection can be long-lasting, and the wound healing can be difficult and also presumably troublesome for the patient. CABG patients' experiences of severe infection in the harvesting site have not been studied before.

AIM

The aim of this study was to describe patients' experiences associated with acquiring a severe infection in the harvesting site after CABG.

METHOD

A qualitative study with descriptive design was conducted at the department of vascular and cardiothoracic surgery in a Swedish university hospital from May to December 2018. Patients diagnosed with a severe surgical site infection in the harvesting site following CABG were included. Data from 16 face-to-face interviews were analysed with inductive qualitative content analysis.

RESULT

The main category, varying impact on body and mind, was the core of the patients' experiences of severe wound infection in the harvesting site after CABG. Two generic categories were identified: physical impact and thoughts about the complication. The patients described experiencing different degrees of pain, anxiety, and limitation in daily life.

CONCLUSION

These findings indicate that a severe infection in the harvesting site after CABG was experienced as an important issue with varying impact. Overall, the participants experienced pain, anxiety, and limitations in daily life. However, most of them were satisfied with the outcome after the wound had healed. Patients should be advised to seek care at an early stage if symptoms of infection occur. Improved individual pain management is needed for those with severe pain, and varied experiences imply a need for person-centred care.

Current practice of saphenous vein graft harvesting in coronary artery bypass graft surgery: an Indian survey

Purpose

The treatment of occluded saphenous vein graft (SVG) is challenging, and thus preventing the graft occlusion is of utmost importance. However, despite its recognized importance, a paucity of data exists regarding how SVGs are handled and preserved. Hence, this survey was conducted to document the techniques of vein graft preservation and handling among cardiac surgeons in India.

Methods

The survey had 26 questions regarding vein graft usage, harvesting, handling, and preservation techniques. Three hundred cardiac surgeons across India participated in this survey between March 2019 and July 2019.

Results

Responses were received from 215 (71.6%) surgeons across 13 states. Around 87% of respondents reported that ≥ 76% of veins were harvested by the open technique. Among the respondents, around 67% used one SVG in ≥ 96% of their patients, 45% used two SVGs in ≥ 86% of their patients, and 38% used ≥ 3 SVGs in < 25% of their patients, respectively. Around 54%, 27%, 9%, and 9% of respondents used autologous whole blood, saline solution, pH-buffered solution, and other solutions, respectively. In addition, 96.74% of respondents heparinized their vein graft preservation solutions, and 98.14% preserved the solution at room temperature. 34.88% and 83.26% of respondents used dual antiplatelet therapy (DAPT) before and after surgery in ≥ 76% of their patients, respectively. 63.26% of the surgeons reported that the patients received DAPT for > 12 months.

Conclusion

There is a significant variance in the process of vein harvesting, preservation, handling, and antiplatelet therapy protocols among various cardiac surgeons across India. Therefore, there is a need for standardization in the practice of vein harvesting.

Syndecan-4 and stromal cell-derived factor-1 alpha functionalized endovascular scaffold facilitates adhesion, spreading and differentiation of endothelial colony forming cells and functions under flow and shear stress conditions

Acellular vascular scaffolds with capture molecules have shown great promise in recruiting circulating endothelial colony forming cells (ECFCs) to promote in vivo endothelialization. A microenvironment conducive to cell spreading and differentiation following initial cell capture are key to the eventual formation of a functional endothelium. In this study, syndecan-4 and stromal cell-derived factor-1 alpha were used to functionalize an elastomeric biomaterial composed of poly(glycerol sebacate), Silk Fibroin and Type I Collagen, termed PFC, to enhance ECFC-material interaction. Functionalized PFC (fPFC) showed significantly greater ECFCs capture capability under physiological flow. Individual cell spreading area on fPFC (1474 ± 63 μm² ) was significantly greater than on PFC (1187 ± 54 μm² ) as early as 2 h, indicating enhanced cell-material interaction. Moreover, fPFC significantly upregulated the expression of endothelial cell specific markers such as platelet endothelial cell adhesion molecule (24-fold) and Von Willebrand Factor (11-fold) compared with tissue culture plastic after 7 days, demonstrating differentiation of ECFCs into endothelial cells. fPFC fabricated as small diameter conduits and tested using a pulsatile blood flow bioreactor were stable and maintained function. The findings suggest that the new surface functionalization strategy proposed here results in an endovascular material with enhanced endothelialization.

Mechanical characterization of human umbilical arteries by thick-walled models: Enhanced vascular compliance by removing an abluminal lining

The decellularized human umbilical artery (HUA) is considered as a promising option for small-diameter, tissue-engineered vascular grafts (TEVGs). Our previous study showed that the HUA bears a thin, watertight lining on its outermost abluminal surface. Removal of this abluminal lining layer improves efficacy of the perfusion-assisted decellularization of the HUA and increases its compliance. As stress across the wall is believed to affect growth and remodeling of the TEVG, it is imperative to mechanically characterize the HUA using thick-walled models. Combining inflation experiments and computational methods, we investigate the mechanical properties of the HUA before and after the abluminal lining removal to examine the HUA's wall mechanics. The inflation tests of five HUAs were performed to obtain the mechanical and geometrical response of the vessel wall before and after the lining layer removal. Using nonlinear hyperelastic models, the same responses are obtained computationally using the thick-walled models. The experimental data are incorporated into the computational models to estimate the mechanical and orientation parameters of the fibers and isotropic matrix of different layers in the HUAs. The parameter fitting of both thick-walled models (before and after the abluminal lining removal) results in most of the R-squared values for measuring the goodness of fitting to be over 0.90 for all samples. The compliance of the HUA increases from a mean value of 2.60% per 100 mmHg before the removal of the lining to a mean value of 4.21% per 100 mmHg after the removal. The results reveal that, although the abluminal lining is thin, it is stiff and capable of supporting majority of the high luminal pressure, and that the inner layer is far less stressed than the abluminal lining. Computational simulations also show that removal of the abluminal lining increases the circumferential wall stress by up to 280 kPa under the in vivo luminal pressure. The integrated computational and experimental approaches provide more accurate estimates of the material behaviors of HUAs employed in grafts and, in turn, the study enhances our understanding of interactions between the graft and the native vessel on vascular growth and remodeling.

Sirolimus-Embedded Silk Microneedle Wrap to Prevent Neointimal Hyperplasia in Vein Graft Model

We investigated the role of a sirolimus-embedded silk microneedle (MN) wrap as an external vascular device for drug delivery efficacy, inhibition of neointimal hyperplasia, and vascular remodeling. Using dogs, a vein graft model was developed to interpose the carotid or femoral artery with the jugular or femoral vein. The control group contained four dogs with only interposed grafts; the intervention group contained four dogs with vein grafts in which sirolimus-embedded silk-MN wraps were applied. After 12-weeks post-implantation, 15 vein grafts in each group were explanted and analyzed. Vein grafts applied with the rhodamine B-embedded silk-MN wrap showed far higher fluorescent signals than those without the wrap. The diameter of vein grafts in the intervention group decreased or remained stable without dilatation; however, it increased in the control group. The intervention group had femoral vein grafts with a significantly lower mean neointima-to-media ratio, and had vein grafts with an intima layer showing a significantly lower collagen density ratio than the control group. In conclusion, sirolimus-embedded silk-MN wrap in a vein graft model successfully delivered the drug to the intimal layer of the vein grafts. It prevented vein graft dilatation, avoiding shear stress and decreasing wall tension, and it inhibited neointimal hyperplasia.