Saphenous vein grafts in contemporary coronary artery bypass graft surgery

Long Saphenous Vein Harvesting: Reviewing Various Techniques

Ischemic heart disease is the leading cause of mortality and morbidity in the Western world. Thus, coronary artery bypass graft is the most common cardiac procedure performed as it remains the gold standard for multiple vessel disease and left main disease. Long saphenous vein is the conduit of choice for coronary artery bypass graft as it is accessible and easy to harvest. Over the previous 4 decades, several techniques have emerged to optimize harvesting and reducing adverse clinical outcomes. The most cited techniques are open vein harvesting, no-touch technique, endoscopic vein harvesting, and standard bridging technique. In this literature review, we aim to summarize current literature for each of the 4 techniques in terms of: (A) graft patency and attrition, (B) myocardial infarction and revascularization, (C) wound infections, (D) postoperative pain, and (E) patient satisfaction.

Symptomatic early coronary graft failure in bypass surgery patients: incidence, predictors and clinical impact

OBJECTIVES

Coronary graft failure (CGF) may occur early after coronary bypass graft surgery (CABG). The study aimed to identify clinical and perioperative risk factors and to evaluate the long-term clinical impact of symptomatic early CGF.

METHODS

Patients who underwent clinically indicated coronary angiography (CAG) prior to post-CABG discharge between 2012 and 2022 were included. Symptomatic early CGF was defined as a dysfunctional coronary graft, evaluated on clinically indicated CAG, caused by stenosis of the proximal or distal anastomosis or bypass conduit, bypass occlusion, thrombosis, reduced flow (TIMI < 1) and kinking/tenting. Patients were divided into symptomatic early CGF and non-early CGF groups. Kaplan-Meier and multivariate analysis estimated cumulative survival free of major adverse cardiovascular events (MACE: death, myocardial infarction and revascularisation) up to 5 years' follow-up and identified predictors of symptomatic early CGF.

RESULTS

A total of 92 patients (79% male, 66.1 ± 10 years old) were included, of whom 55 (59.8%) had symptomatic early CGF. Baseline characteristics, surgical parameters and post-surgical parameters potentially indicative of ischaemia were comparable between groups. Patients with symptomatic early CGF had a significantly lower MACE rate over a median follow-up period of 33 months (p = 0.023). Venous graft integration (p = 0.005), Y‑graft configuration (p = 0.002) and prolonged inotropic support (p = 0.032) were associated with symptomatic early CGF.

CONCLUSIONS

Symptomatic early CGF was observed in the majority of post-CABG patients undergoing clinically indicated CAG prior to discharge. Patients with symptomatic early CGF exhibited higher MACE rates over a median follow-up period of 33 months. Venous graft integration, Y‑graft configuration and prolonged use of inotropic agents were associated with symptomatic early CGF. However, these clinical findings should be interpreted with caution.

Thrombospondin-1 Small Interfering RNA-Loaded Lipid Nanoparticles Inhibiting Intimal Hyperplasia of Electrospun Polycaprolactone Vascular Grafts

Synthetic vascular grafts are promising conduits for small caliber arteries. However, due to restenosis caused by intimal hyperplasia, they cannot keep long patency in vivo. In this work, through single cell RNA sequencing, we found that thrombospondin-1 (THBS1) was highly expressed in the regenerated smooth muscle cells (SMCs) in electrospun polycaprolactone (PCL) vascular grafts. The expression of THBS1 by injured SMCs was confirmed in a balloon-induced vascular injury model. Downregulation of Thbs1 expression maintained contractile phenotypes of SMCs and reduced neointimal hyperplasia after vascular injury via inhibition of FGFR1/EGR1 signaling by decreasing THBS1 expression. THBS1 small interfering RNA (THBS1-siRNA) was then loaded into macrophage membrane (MM) hybrid lipid nanoparticles (Lipid NP@MM), which were used to modify PCL vascular grafts via polydopamine (PDA) coatings. Lipid NP@MM not only protected THBS1-siRNA from degradation but also improved its internalization by SMCs to decrease the level of THBS1 expression. PCL vascular grafts modified with PDA coatings and Thbs1-siRNA-loaded Lipid NP@MM showed significantly reduced intimal hyperplasia. Thus, the downregulation of THBS1 expression in regenerated SMCs in vascular grafts is a promising strategy to inhibit intimal hyperplasia during vascular graft regeneration in vivo.

α-Ketoglutaric Acid Reprograms Macrophages by Altering Energy Metabolism to Promote the Regeneration of Small-Diameter Vascular Grafts

Small-diameter vascular grafts still cannot clinically replace autologous blood vessels due to high restenosis rates caused by long-term inflammatory infiltration. Foreign body reactions to vascular grafts induce macrophages to adopt the pro-inflammatory M1 phenotype, releasing inflammatory factors such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). This induces a phenotypic switch in smooth muscle cells, eventually leading to intimal hyperplasia. Herein, we constructed small-diameter artificial vascular grafts capable of modulating immune responses through the controlled release of α-ketoglutaric acid (α-KG). Our findings verify that the delivery of α-KG reprograms the macrophage phenotype from a pro-inflammatory M1 to an anti-inflammatory and pro-repair M2 phenotype by regulating the energy metabolism of the tricarboxylic acid cycle (TAC). More interestingly, the delivery of α-KG positively influences the behavior of vascular cells by enhancing the proliferation of human umbilical vein endothelial cells (HUVECs) and inhibiting the expansion of mouse aortic vascular smooth muscle cells (MOVAS), thereby reducing vascular restenosis. In vivo evaluation in rabbit carotid artery replacement confirms the optimal performance of α-KG-doped vascular grafts in terms of endothelial coverage and long-term patency. Collectively, our work presents a promising approach for creating artificial vascular grafts with inflammatory regulation to ensure rapid endothelialization and sustained patency.

Mechanical Activation of cPLA2 Impedes Fatty Acid β-Oxidation in Vein Grafts

High-magnitude cyclic stretch from arterial blood pressure significantly contributes to the excessive proliferation and migration of vascular smooth muscle cells (VSMCs), leading to neointima formation in vein grafts. However, the molecular mechanisms remain unclear. This study highlights the critical role of cytosolic Phospholipase A2 (cPLA2)/ Yin Yang 1 (YY1)/ carnitine palmitoyltransferase 1b (CPT1B) signaling in coordinating VSMC mechanical activation by inhibiting fatty acid β-oxidation. Metabolomic analysis showed that a 15%-1 Hz arterial cyclic stretch, compared to a 5%-1 Hz venous stretch, increased long-chain fatty acids in VSMCs. cPLA2, identified as a mechanoresponsive molecule, produces excessive arachidonic acid (ArAc) under the 15%-1 Hz stretch, inhibiting CPT1B expression, a key enzyme in fatty acid β-oxidation. ArAc promotes transcription factor YY1 degradation, downregulating CPT1B. Inadequate fatty acid oxidation caused by knockdown of CPT1B or YY1, or etomoxir treatment, increased nuclear membrane tension, orchestrating the activation of cPLA2. Overexpressing CPT1B or inhibiting cPLA2 reduced VSMC proliferation and migration in vein grafts, decreasing neointimal hyperplasia. This study uncovers a novel mechanism in lipid metabolic reprogramming in vein grafts, suggesting a new therapeutic target for vein graft hyperplasia.

Multimodal Data-Driven Prognostic Model for Predicting Long-Term Prognosis in Patients With Ischemic Cardiomyopathy and Heart Failure With Preserved Ejection Fraction After Coronary Artery Bypass Grafting: A Multicenter Cohort Study

BACKGROUND

Limited data from the literature are available to assess the efficacy of coronary artery bypass grafting in patients with ischemic cardiomyopathy and heart failure with preserved ejection fraction. Therefore, our objective was to use machine learning techniques integrating clinical features, biomarker data, and echocardiography data to enhance comprehension and risk stratification in patients diagnosed with ischemic cardiomyopathy and heart failure with preserved ejection fraction who have undergone coronary artery bypass grafting surgery.

METHODS AND RESULTS

For this study, 294 patients with ischemic cardiomyopathy and heart failure with preserved ejection fraction who underwent coronary artery bypass grafting surgery were assigned to the development cohort (n=176) and the independent validation cohort (n=118). A total of 52 clinical variables were extracted for each patient. The principal clinical end point was the incidence of major adverse cardiovascular events, encompassing cardiac mortality, acute myocardial infarction, acute heart failure, and graft failure. From least absolute shrinkage and selection operator regression, 4 predictors were selected for the final prediction nomogram: diabetes, hypertension, the systemic immune-inflammation index, and NT-proBNP (N-terminal pro-B-type natriuretic peptide). The prediction nomogram achieved satisfactory prediction performance in both the development cohort (C index, 0.768 [95% CI, 0.701-0.835]) and independent validation cohort (C index, 0.633 [95% CI, 0.521-0.745]). Adequate calibration was noted for the likelihood of major adverse cardiovascular events in both the development and independent validation cohorts. Decision curve analysis confirmed the clinical usefulness of the established prediction nomogram.

CONCLUSIONS

A clinically feasible prognostic model, based on preoperative multimodal data, was developed for risk stratification of patients with ischemic heart and heart failure with preserved ejection fraction who receive coronary artery bypass grafting surgery.

REGISTRATION

https://www.chictr.org.cn; Unique identifier: ChiCTR2300074439.

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.

o8G-miR-6513-5p/BCL2L13 Axis Regulates Mitophagy during Oxidative Stress in the Human Saphenous Vein Endothelial Cells

Venous graft decay (VGD) occurs in coronary artery bypass grafting (CABG), and ischemia-reperfusion oxidative stress injury during the operation is involved in VGD. To explore the cellular phenotypic changes during this process, a stable oxidative stress model of human saphenous vein endothelial cells (HSVECs) is constructed. Through proteomics and cell experiments, it is found that the expression of BCL2L13 is upregulated during oxidative stress of HSVECs, and BCL2L13 regulated mitophagy through receptor-mediated interaction with LC3 and plays a role in cell protection. During oxidative stress, intracellular o8G epigenetic modification occurs, and the o8G modification of miR-6513-5p causes this molecule to lose its targeted regulation of BCL2L13 and participates in the upregulation of BCL2L13. There is a regulatory pathway of o8G modification-BCL2L13-LC3-mitophagy when oxidative stress occurs in HSVECs.

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.

Predictive value of pericoronary fat attenuation index for graft occlusion after coronary artery bypass grafting

PURPOSE

Based on coronary computed tomography angiography (CCTA), this study aimed to evaluate the predictive value of pericoronary fat attenuation index (FAI) for graft occlusion in patients following coronary artery bypass grafting (CABG).

MATERIALS AND METHODS

The clinical and imaging data of 100 patients with coronary artery disease (CAD) who underwent CCTA and subsequently received successful CABG between December 2012 and March 2024 were retrospectively collected. According to the subsequent CCTA evaluation of grafts, they were categorized into occlusion group (n = 27) and patency group (n = 73). Based on CCTA images, FAI of the proximal segment of the three coronary arteries and epicardial adipose tissue (EAT) parameters were measured and compared between the two groups. The Cox regression model was employed to screen the independent predictors of graft occlusion. The predictive model was constructed, and the receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic performance of the model.

RESULTS

Among the 100 cases, 74 were males, with a mean age was 62.42 ± 7.57 years. During the 15.50 (5.00, 36.75) months follow-up period, grafting vessel occlusion occurred in 27 patients (27.0%). The right coronary artery (RCA) in occlusion group was -73.36 ± 7.24HU, which was notably higher compared to patency group (-79.93 ± 9.75HU) (P < 0.05). Multivariable Cox regression analysis indicated that RCA FAI (HR = 5.205, 95% CI 1.938-13.979; P = 0.001) was independently correlated with graft occlusion, with an optimal cutoff value of -79.39 HU.RCA FAI added incremental prognostic value beyond clinical characteristics for patients following CABG (AUC 0.784 vs. 0.677, P = 0.027).

CONCLUSIONS

The RCA FAI can serve as a crucial predictor for graft occlusion in patients following CABG, enabling early identification of high-risk individuals and facilitating timely and effective intervention measures to enhance patient prognosis.

Irisin suppresses PDGF-BB-induced proliferation of vascular smooth muscle cells in vitro by activating AMPK/mTOR-mediated autophagy

Restenosis is a pivotal factor that restricts the efficacy of coronary artery bypass grafting. Inhibition of vascular smooth muscle cells (VSMCs) proliferation can improve intimal hyperplasia and lumen stenosis. Irisin, a polypeptide secreted by muscle cells, has been demonstrated to have a protective role in various cardiovascular diseases. However, the effect and mechanism of irisin on VSMCs proliferation and phenotype switching remain unclear. Cell proliferation ability was assessed using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and 5-ethynyl-2'-deoxyuridine (EdU) incorporation. Cell cycle analysis was performed using flow cytometry, while expression levels of contractile and synthesis-related proteins were determined through RT-qPCR and Western blot. The VSMCs were infected with an adenovirus carrying GFP-LC3, and the proportion of cells showing positive expression was assessed. Additionally, the formation of autophagic lysosomes in cells was observed through transmission electron microscopy. In this study, we have demonstrated the inhibitory effects of irisin on the proliferation and phenotypic transition of platelet-derived growth factor-BB (PDGF-BB)-induced VSMCs. More importantly, we have discovered that irisin can activate the AMP-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) signaling pathway to mediate autophagy in PDGF-BB-induced VSMCs. The inhibitory effect of irisin on PDGF-BB-induced VSMCs proliferation was significantly attenuated by the AMPK inhibitor, Compound C. Conversely the mTOR inhibitor, rapamycin further enhanced the inhibitory effect of irisin on PDGF-BB induced VSMCs proliferation. In conclusion, our findings suggest that irisin effectively suppresses the aberrant proliferation of VSMCs following PDGF-BB stimulation by modulating autophagy levels through the AMPK/mTOR signaling pathway.

The Role of Advanced Glycation End Products in Saphenous Vein Graft Failure

OBJECTIVE

We aimed to investigate the relationship between advanced glycation end product (AGE) levels in patients with saphenous vein graft (SVG) failure and in patients without SVG failure.

SUBJECTS AND METHODS

In our study, 55 patients with a history of previous coronary artery bypass grafting (CABG) surgery, who subsequently underwent coronary angiography for any reason and were found to have either SVG occlusion or significant lesions, were included as study patients. Additionally, 55 patients who have had CABG surgery without SVG failure for at least 1 year served as the control group. AGE values of the patients were measured using the skin autofluorescence method.

RESULTS

In our study results, we observed a significant difference in AGE levels between the two groups of patients with similar demographic characteristics (SVG failure groups AGE 3.2 [2.8-3.6] vs. control groups AGE 2.4 [2.1-2.7] p < 0.001). In the receiver operating characteristic curve analysis, we determined the ability of AGE levels to detect SVG failure with an area under the curve of 0.869. We found that in patients with AGE >3, it could detect SVG failure with a sensitivity of 70.9% and a specificity of 87.3%.

CONCLUSIONS

Our results demonstrate that AGE levels can predict SVG failure risk inexpensively, easily, and quickly.

Outcome of Saphenous Vein Graft Percutaneous Coronary Intervention Using Contemporary Drug-Eluting Stents: A SCAAR Report

Background

Percutaneous coronary intervention (PCI) of saphenous vein grafts (SVG) is associated with poor outcomes and is often regarded as inferior to native vessel PCI. We investigated clinical outcomes of SVG-PCI using contemporary drug-eluting stents (DES), in a complete, nationwide population.

Methods

The complete Swedish Coronary Angiography and Angioplasty Registry (SCAAR) was used to identify all patients in Sweden who underwent SVG-PCI with a contemporary DES between 2013 and 2020. Baseline characteristics, procedures, and outcomes were described.

Results

A total of 2198 SVG-PCI procedures with 3106 contemporary DES were included. Patients had a high incidence of comorbidities such as diabetes (40%), prior myocardial infarction (MI) (69%), and acute coronary syndrome (74%) at presentation. SVG-PCI procedures commonly involved multiple DES (41%). Native vessel PCI, in addition to SVG-PCI, was performed in only 13% of procedures. At 1 year, adverse clinical outcomes were frequent as exemplified by any death (9.2%), MI (9.1%), or revascularization (21.1%), whereas stent and lesion-related outcomes on a patient level were less common: stent thrombosis (1.2%), in-stent restenosis (4.3%) and target lesion revascularization (4.3%). Similarly, at 3 years, clinical outcomes were frequent: death (19.8%), MI (21.1%), revascularization (32.8%); and stent-related outcomes were less common: stent thrombosis (2.9%), restenosis (10.8), and target lesion revascularization (13.6%).

Conclusions

In this nationwide cohort of patients who underwent SVG-PCI with contemporary DES, patients were characterized by a high-risk profile and high rates of adverse clinical events. However, the incidence of stent and lesion-related events was low.

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.

Transatlantic analysis of patient profiles and mid-term survival after isolated coronary artery bypass grafting: a head-to-head comparison between the European DuraGraft Registry and the US STS Registry

Introduction

Although cardiovascular surgery societies in Europe and the USA constantly strive for the exchange of knowledge and best practices in coronary artery bypass grafting (CABG), the available evidence on whether such efforts result in similar patient outcomes is limited. Therefore, in the present analysis, we sought to compare patient profiles and overall survival outcomes for up to 3 years between large European and US patient cohorts who underwent isolated CABG.

Methods

Patients from the European DuraGraft Registry (n = 2,522) who underwent isolated CABG at 45 sites in eight different European countries between 2016 and 2019 were compared to randomly selected patients from the US STS database who were operated during the same period (n = 294,725). Free conduits (venous and arterial grafts) from the DuraGraft Registry patients were intraoperatively stored in DuraGraft, an endothelial damage inhibitor, before anastomosis, whereas grafts from the STS Registry patients in standard-of-care solutions (e.g., saline). Propensity score matching (PSM) models were used to account for differences in patient baseline and surgical characteristics, using a primary PSM with 35 variables (2,400 patients matched) and a secondary PSM with 25 variables (2,522 patients matched, sensitivity analysis). The overall survival for up to 3 years after CABG was assessed as the primary endpoint.

Results

The comparison of patient profiles showed significant differences between the European and US cohorts. The European patients had more left main disease, underwent more off-pump CABG, and received more arterial grafts together with more complete arterial grafting procedures. In contrast, the US patients received more distal anastomoses with more saphenous vein grafts (SVGs) that were mainly harvested endoscopically. Such differences, however, were well balanced after PSM for the mortality comparison. Mortality comparison at 30 days, 12 months, and 24 months between the European and US patients was 2.38% vs. 1.96%, 4.32% vs. 4.79%, and 5.38% vs. 6.96%, respectively. At 36 months, the mortality was significantly lower in the European patients than that of their US counterparts (7.37% vs. 9.65%; p-value = 0.016). The estimated hazard ratio (HR) was 1.29 (95% CI 1.05-1.59).

Conclusion

This large-scale transatlantic comparative analysis shows that there are some significant differences in patient profiles between large cohorts of European and US patients. These differences were adjusted by using PSM for the mortality analysis. No significant difference in mortality was detected between groups through 2 years, but survival was significantly better in the European DuraGraft Registry patients at 3 years post-CABG.

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.

Superior Measurement Accuracy of Digital Thickness Gauge Versus Digital Vernier Caliper in Determining Venous Tissue Thickness

Background In determining mechanical characteristics, the accuracy of the thickness of the specimens can influence the biomechanical behavior, especially in the case of human tissues, where there is an important variability. This study aims to compare the accuracy of two routine measuring instruments, i.e., the digital vernier caliper and the digital thickness gauge, when measuring the thickness of venous specimens multiple times. Methodology In this study, we used 12 tubular vena cava specimens obtained from common breed pigs aged 18-24 weeks at the time of sacrifice from a local slaughterhouse. The measurements were performed using a digital vernier caliper (Multicomp PRO MP012475) for the first four protocols and a digital thickness gauge (Mitutoyo 547-500S) for the fifth protocol. In the first protocol, three measurements were taken on the same side, and their average was recorded as the sample thickness. The second protocol involved taking measurements on two opposite sides, and the average of these measurements was recorded as the sample thickness. In the third protocol, the thickness of each side was measured at its midpoint, and the average of the four measurements was recorded as the sample thickness. In the last protocol using a digital vernier caliper, the thickness of the vernier specimens was calculated as the average of the measurements taken at each corner of the square sample. Finally, for the fifth protocol, three consecutive measurements were taken using the digital thickness gauge, and their average was recorded as the final thickness of the sample. Results In the first protocol, we observed lower values during the first measurement in comparison to the second (0.409 ± 0.063 vs. 0.536 ± 0.064, p < 0.0001) and the third (0.409 ± 0.063 vs. 0.528 ± 0.055, p = 0.0001). Moreover, with the second protocol, we observed lower values during the first two measurements in comparison to the third measurement (p = 0.0279 and p = 0.0054). Regarding protocols three and four, we recorded higher values for the second and third measurements than the first one, with higher values for the third measurement than the second one. In the fifth protocol, there were no significant statistical differences between the three consecutive measurements (p = 0.953, p = 0.742, and p = 0.897). Further, we examined the variations in sample thickness determined using each of the protocols proposed for the digital vernier caliper, as well as the values obtained with the digital thickness gauge protocol. As a result, during the first and second measurements, we observed lower thickness values for the venous wall samples using the first four protocols compared to the fifth protocol (for all p < 0.05). However, no differences were noted between the five protocols during the third measurement. Conclusions The digital thickness gauge Mitutoyo 547-500S provided superior accuracy with no difference between three successive measurements of venous wall thickness, regardless of the examiner's experience. Accurately determining the thickness of venous specimens is crucial for calculating the tissue's biomechanical properties.

Early Experiences of Serbian Surgeons Using No-Touch Technique for Vein Conduits in CABG Patients: A Follow-Up Study with Multi-Slice CT Angiography

Background and Objectives: The saphenous vein graft (SVG) remains the most frequently used conduit worldwide, despite its common disadvantage of early graft failure. To solve the problem and reduce the SVG damage, Souza implemented a new technique where a vein is harvested with surrounding fascia and fat tissue (the so-called no-touch technique). Materials and Methods. A prospective study conducted from February 2019 to June 2024 included 23 patients who underwent myocardial revascularization using a no-touch vein, with follow-up control examinations using computed tomographic angiography to detect graft stenosis or occlusion. Results. Of the entire patient group, 17 (73.9%) were male, with a mean age of 67.39 ± 7.71 years. The mean follow-up period was 25 months. There were no major adverse cardiovascular or cerebrovascular events (MACCEs) during hospitalization, although one patient died in the hospital. Another patient died due to malignancy, but no MACCEs occurred during the follow-up period. According to multi-slice CT coronary angiography, the results were impeccable, with an astonishing 100% patency observed in all 20 IMA grafts and 58 no-touch SVGs examined. Conclusions. The excellent patency rate during the early follow-up period confirmed that the no-touch technique is a good option for surgical revascularization.

Outcomes of myocardial revascularization in patients with obesity and multivessel coronary artery disease

BACKGROUND

There is uncertainty regarding the best revascularization approach-whether coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI)-for obese patients suffering from multi-vessel coronary artery disease.

RESULTS

406 patients with low and intermediate SYNTAX scores (SS) underwent PCI with drug-eluting stents (n = 200, 100 with SS ≤ 22, and 100 with SS 23-32) and CABG (n = 206, 100 with SS ≤ 22, and 106 with SS 23-32). Patients were also categorized by body mass index (BMI): normal weight (12%, 48 patients), overweight (41.6%, 169 patients), and obese (46.6%, 189 patients). The follow-up period averaged 9 ± 1.9 years. The endpoints of the study were as follows: major adverse cardiac and cerebrovascular events, a repeat revascularization, diminished left ventricular ejection fraction (LVEF), and high SS (≥ 33) observed over time. When comparing PCI and CABG in overweight individuals, the risk of myocardial infarction (MI) following PCI was greater than after CABG (Hazard Ratio [HR] 2.7, 95% Confidence Interval [CI] 1.1-6.7, p = 0.03). In patients with overweight and Class I obesity, CABG was associated with the risk of coronary atherosclerosis progression (SS ≥ 33) (HR 4.4, 95% CI 1.5-13, p = 0.009 and HR 4.9, 95% CI 1.9-12, p = 0.001, respectively); whereas PCI was connected with the likelihood of repeat revascularization (HR 2.7, 95% CI 1.6-4.55, p < 0.0001 and HR 2, 95% CI 1.3-3.1, p = 0.002, respectively). At the same time, for stented patients, Class III obesity was associated with the risk of repeat revascularization (HR 2.5, 95% CI 1.02-6, p = 0.044).

CONCLUSION

There were no significant weight-related impacts on long-term outcomes among patients who underwent surgery. Whereas in stented patients, Class III obesity was associated with the risk of repeat revascularization. When comparing PCI and CABG, for overweight and Class I obesity patients, CABG was associated with a likelihood of coronary atherosclerosis progression (SS ≥ 33), while PCI was linked to the risk of repeat revascularization. For overweight patients, CABG outperformed PCI in terms of the risk of MI. For other adverse events in patients of different weight categories, PCI and CABG did not reveal any significant benefits.

Polyzwitterion-grafted decellularized bovine intercostal arteries as new substitutes of small-diameter arteries for vascular regeneration

Coronary artery bypass grafting is acknowledged as a major clinical approach for treatment of severe coronary artery atherosclerotic heart disease. This procedure typically requires autologous small-diameter vascular grafts. However, the limited availability of the donor vessels and associated trauma during tissue harvest underscore the necessity for artificial arterial alternatives. Herein, decellularized bovine intercostal arteries were successfully fabricated with lengths ranging from 15 to 30 cm, which also closely match the inner diameters of human coronary arteries. These decellularized arterial grafts exhibited great promise following poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) grafting from the inner surface. Such surface modification endowed the decellularized arteries with superior mechanical strength, enhanced anticoagulant properties and improved biocompatibility, compared to the decellularized bovine intercostal arteries alone, or even those decellularized grafts modified with both heparin and vascular endothelial growth factor. After replacement of the carotid arteries in rabbits, all surface-modified vascular grafts have shown good patency within 30 days post-implantation. Notably, strong signal was observed after α-SMA immunofluorescence staining on the PMPC-grafted vessels, indicating significant potential for regenerating the vascular smooth muscle layer and thereby restoring full structures of the artery. Consequently, the decellularized bovine intercostal arteries surface modified by PMPC can emerge as a potent candidate for small-diameter artificial blood vessels, and have shown great promise to serve as viable substitutes of arterial autografts.

Exploring the Potential of Saphenous Vein Grafts Ex Vivo: A Model for Intimal Hyperplasia and Re-Endothelialization

Coronary artery bypass grafting (CABG) utilizing saphenous vein grafts (SVGs) stands as a fundamental approach to surgically treating coronary artery disease. However, the long-term success of CABG is often compromised by the development of intimal hyperplasia (IH) and subsequent graft failure. Understanding the mechanisms underlying this pathophysiology is crucial for improving graft patency and patient outcomes. Objectives: This study aims to explore the potential of an ex vivo model utilizing SVG to investigate IH and re-endothelialization. Methods: A thorough histological examination of 15 surplus SVG procured from CABG procedures at Hospital Canselor Tuanku Muhriz, Malaysia, was conducted to establish their baseline characteristics. Results: SVGs exhibited a mean diameter of 2.65 ± 0.93 mm with pre-existing IH averaging 0.42 ± 0.13 mm in thickness, alongside an observable lack of luminal endothelial cell lining. Analysis of extracellular matrix components, including collagen, elastin, and glycosaminoglycans, at baseline and after 7 days of ex vivo culture revealed no significant changes in collagen but demonstrated increased percentages of elastin and glycosaminoglycans. Despite unsuccessful attempts at re-endothelialization with blood outgrowth endothelial cells, the established ex vivo SVG IH model underscores the multifaceted nature of graft functionality and patency, characterized by IH presence, endothelial impairment, and extracellular matrix alterations post-CABG. Conclusions: The optimized ex vivo IH model provides a valuable platform for delving into the underlying mechanisms of IH formation and re-endothelialization of SVG. Further refinements are warranted, yet this model holds promise for future research aimed at enhancing graft durability and outcomes for CAD patients undergoing CABG.

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.

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.

Mapping the blueprint of artificial blood vessels research: a bibliometric analysis of publications in the 21st century

BACKGROUND

Vascular diseases represent a significant causes of disability and death worldwide. The demand for artificial blood vessels is increasing due to the scarce supply of healthy autologous vessels. Nevertheless, the literature in this area remains sparse and inconclusive.

METHODS

Bibliometrics is the study of quantitative analysis of publications and their patterns. This study conducts a bibliometric analysis of publications on artificial blood vessels in the 21st century, examining performance distribution, research trajectories, the evolution of research hotspots, and the exploration of the knowledge base. This approach provides comprehensive insights into the knowledge structure of the field.

RESULTS

The search retrieved 2,060 articles, showing a consistent rise in the publication volume and average annual citation frequency related to artificial blood vessels research. The United States is at the forefront of high-quality publications and international collaborations. Among academic institutions, Yale University is a leading contributor. The dominant disciplines within the artificial blood vessels sector include engineering, biomedical sciences, materials science, biomaterials science, and surgery, with surgery experiencing the most rapid expansion.

CONCLUSIONS

This study is the inaugural effort to bibliometric analyze and visualize the scholarly output in the artificial blood vessels domain. It provides clinicians and researchers with a reliable synopsis of the field's current state, offering a reference point for existing research and suggesting new avenues for future investigations.

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.

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.