Limiting Injury During Saphenous Vein Graft Preparation For Coronary Arterial Bypass Prevents Metabolic Decompensation

The Predictive Value of Pan-Immune-Inflammation Value for Saphenous Vein Graft Disease in Post-Coronary Artery Bypass Grafting Patients

Background: Coronary artery bypass grafting (CABG) remains the gold standard treatment for patients with significant coronary artery disease (CAD) and high-risk profiles for percutaneous coronary intervention. Despite the frequent use of saphenous vein grafts (SVGs) in CABG, their patency rates are lower than those of arterial grafts. Identifying noninvasive methods to determine SVG patency is crucial. Aims: This study investigates the relationship between a novel inflammation marker, pan-immune-inflammation value (PIV), and SVG patency in post-CABG patients. Methods: The study included 507 patients who underwent coronary angiography (CAG) due to clinical indications between 2016 and 2023. Patients who had undergone CABG at least one year prior with at least one SGV used were divided into two groups based on the presence or absence of SVG stenosis (SGVS). Results: Among the 507 patients, 244 had SVGS. Patients with SVGS exhibited higher levels of diabetes mellitus and inflammatory markers such as NLR, SII, CAR, and PIV. Multivariate analysis identified PIV as an independent predictor of SVGS. ROC analysis showed that a PIV cut-off value > 315.5 predicted SVGS with 75.8% sensitivity and 68.6% specificity. Conclusions: PIV, a simple and easily measurable marker, demonstrated strong predictive value for SVGS in post-CABG patients.

Improvement of the outcome of the saphenous vein graft when connected to the internal thoracic artery

Background

Since 2000, we have been grafting the right coronary artery system (RCAs) using the proximal portion of the right internal thoracic artery (RITA) as the inflow of the saphenous vein graft (SVG) to increase the number of patients undergoing beating heart complete myocardial revascularization.

Methods

From 2000 to 2022, 928 consecutive patients underwent SVG on the RCAs. In 546 patients (58.8%), the inflow was the RITA (I-graft group), and in 382 patients (41.2%), the inflow was the aorta (Ao-graft group). The inclusion criteria were age ≤75 years, ejection fraction >35%, only one SVG per patient, bilateral internal thoracic arteries as a Y-graft on the left system (three-vessel disease, n = 817, 88.0%) or left internal thoracic artery on the left anterior descending artery and RITA + SVG on the RCAs (two-vessel disease, n = 111, 12.0%). Propensity matching identified 306 patients per group. After a median follow-up of 8 (5-10) years, graft patency was assessed by coronary computed tomographic angiography in 132 patients (64 in the I-graft group and 68 in the Ao-graft group).

Results

Early results were similar in both groups. The I-graft group had higher 10-year survival and freedom from main adverse cardiac events (90.0 ± 2.0 vs. 80.6 ± 3.8, p = 0.0162, and 81.3 ± 2.7 vs. 64.7 ± 5.6, p = 0.0206, respectively). When RITA was the inflow, SVG had a higher estimated 10-year patency rate (82.8% ± 6.5 vs. 58.8% ± 7.4, p = 0.0026) and a smaller inner lumen diameter (2.7 ± 0.4 vs. 3.4 ± 0.6 mm, p < 0.0001).

Conclusion

When the inflow is the RITA, SVG grafted to the RCAs (I-graft) may result in a higher patency rate and better outcome than when the inflow is the ascending aorta (Ao-graft). The continuous supply of nitric oxide by RITA may be the cause of the higher patency rate of the I-graft, which can behave like an arterial conduit.

Antithrombotic strategies for preventing graft failure in coronary artery bypass graft

Coronary artery bypass graft (CABG) procedures face challenges related to graft failure, driven by factors such as acute thrombosis, neointimal hyperplasia, and atherosclerotic plaque formation. Despite extensive efforts over four decades, the optimal antithrombotic strategy to prevent graft occlusion while minimizing bleeding risks remains uncertain, relying heavily on expert opinions rather than definitive guidelines. To address this uncertainty, we conducted a review of randomized clinical trials and meta-analyses of antithrombotic therapy for patients with CABG. These studies examined various antithrombotic regimens in CABG such as single antiplatelet therapy (aspirin or P2Y12 inhibitors), dual antiplatelet therapy, and anticoagulation therapy. We evaluated outcomes including the patency of grafts, major adverse cardiovascular events, and bleeding complications and also explored future perspectives to enhance long-term outcomes for CABG patients. Early studies established aspirin as a key component of antithrombotic pharmacotherapy after CABG. Subsequent randomized controlled trials focused on adding a P2Y12 inhibitor (such as clopidogrel, ticagrelor, or prasugrel) to aspirin, yielding mixed results. This article aims to inform clinical decision-making and guide the selection of antithrombotic strategies after CABG.

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.

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.

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.

Effect of preservation solution and distension pressure on saphenous vein's endothelium

OBJECTIVES

Approaches to improve saphenous vein (SV) patency in coronary artery bypass graft (CABG) surgery remain relevant. This study aimed to evaluate the effects of different preservation solutions and different pressures of intraluminal distention on the endothelium of SV segments in CABG.

METHODS

Forty-two SV segments obtained from 12 patients undergoing CABG were divided into 7 groups. Group 1 (control) was prepared without preservation or intraluminal distension, while the other 6 groups were preserved in autologous heparinized autologous arterial blood or normal saline (NS), with distention pressures 30, 100 and 300 mmHg. To assess the effects of using these solutions and pressures on the endothelium, the grafts were analysed by scanning electron microscopy, with the measurement of endothelial damage degree.

RESULTS

Segments in group 1 showed minimal endothelial damage. SV grafts preserved with NS had significantly greater endothelial damage both compared to the control group and compared to groups preserved with autologous arterial blood (P < 0.001). Segments distended with pressures up to 100 mmHg showed less damage when compared to those distended at 300 mmHg, with the ones subjected to higher pressures presenting a maximum degree of damage, with considerable loss and separation of endothelial cells, extensive foci of exposure of the basement membrane and numerous fractures of the intimate layer, without differences regarding the solution used.

CONCLUSIONS

Preparation of SV using NS and with intraluminal distension pressures above 100 mmHg is factors related to increased damage to the venous endothelium.

[Method of optimal hydraulic dilatation of venous conduits for coronary artery bypass grafting]

Hydraulic dilatation is used in everyday cardiac surgical practice for assessment of leak-proofness and prevention of spasm of autovenous shunts. The classical technique envisages manual high-pressure solution injection, which exerts a negative effect on venous conduits and is one of the causes of incompetence of shunts in the postoperative period. Limiting pressure during hydraulic dilatation is necessary to minimize morphological changes and preserve functional viability of venous conduits. The purpose of the present study was to develop and assess efficacy of a standardized methodology of controlled hydraulic dilatation of venous conduits. We worked out an original technique of controlled hydraulic dilatation of venous conduits under perfusion pressure of artificial circulation. This was followed by assessing morphological changes and functional viability of venous segments after controlled hydraulic dilatation as compared with veins after conventional uncontrolled hydraulic dilatation and the control intact veins. Uncontrolled hydraulic dilatation was accompanied by endothelial damage (p<0.05), multiple conduit wall tears (p<0.05) according to the findings of light microscopy, leading to a significant decrease in the functional vitality of the venous conduit (a decreased reaction to hyperpotassium solution, phenylephrine, acetylcholine and sodium nitroprusside (p<0.05) according to the findings of biophysical examination. Our original technique of controlled hydraulic dilatation of venous conduits under perfusion pressure of artificial circulation made it possible not only to evaluate leak-proofness of the vessel but also to achieve comparable to the control segments parameters of structural integrity of the venous wall and functional viability of the conduit. Thus, using the developed method of controlled hydraulic dilatation makes it possible to minimize morphofunctional alterations in venous conduits, influencing the function of autovenous shunts.

The Role of Tomographic Ultrasonography in Conduit Mapping before Coronary Artery Bypass Grafting

Objective

To assess the performance of tomographic ultrasonography (TUS) in providing images that will enable optimum choice of vein segment to harvest for coronary artery bypass grafting (CABG).

Methods

This was a prospective study of diagnostic accuracy. The index test was tomographic ultrasonography. The reference standard was intraoperative observation. The study was performed at the Vascular Imaging and Cardiothoracic Department at Wythenshawe Hospital, Manchester. Patients undergoing CABG who require vein mapping were included in the study. The main outcome measures were the number of tributaries identified in harvested vein segments, presence of varicosities, and usable length of vein.

Results

The TUS correctly identified 89 out of 111 vein tributaries in 10 patients resulting in a sensitivity of 80.2%. This resulted in a p value of 0.000001 using an exact binomial test, with a prior probability of 0.5. TUS had a sensitivity of 66.7% and a specificity of 100% in the identification of varicosities over 14 patients. TUS had 90% agreement with intraoperative observation in assessing usable length of vein over 14 patients.

Conclusions

Our results show that TUS has a high sensitivity in identifying vein tributaries. This can be used to select veins with fewer tributaries for harvesting should TUS be used for preoperative vein mapping before CABG.