Saphenous vein grafts: to use or not to use?

The choice of the graft conduit is crucial to the success of coronary artery bypass grafting (CABG) because the patency of a coronary conduit is closely associated with an uneventful postoperative course and better long-term patient survival. From the beginning of coronary bypass surgery venous conduits particularly the great saphenous veins (GSV) have been the most frequently used coronary conduit from the beginning of the coronary bypass surgery. However, over the last decade or so, coronary bypass graft surgery with arterial revascularization of all diseased coronaries has shown to be efficient because arterial grafts have better long-term patency, especially left internal mammary artery (LIMA), compared with venous grafts. Early vein graft failure coupled with occlusion is the most important limitation of saphenous vein grafts. Nevertheless, vein grafting is still an integral part of cardiac surgical practice. This review provides a summary of the patency rates, technical features and certain characteristics of the venous conduits. It also examines the current understanding and knowledge of venous histology, vein graft pathology and the associated endothelial and smooth muscle cell physiology and pharmacology. In addition, the existing and the emerging strategies to combat and control vein graft intimal hyperplasia and accelerated atherosclerosis are reviewed in detail.     

Saphenous vein grafts: to use or not to use?

The choice of the graft conduit is crucial to the success of coronary artery bypass grafting (CABG) because the patency of a coronary conduit is closely associated with an uneventful postoperative course and better long-term patient survival. From the beginning of coronary bypass surgery venous conduits particularly the great saphenous vein (GSV) has been the most frequently used coronary conduit. However, over the last decade or so, coronary bypass graft surgery with arterial revascularization of all diseased coronaries has shown to be efficient because arterial grafts have better long-term patency, especially left internal mammary artery (LIMA), compared with venous grafts. Early vein graft failure coupled with occlusion is the most important limitation of saphenous vein grafts. Nevertheless, vein grafting is still an integral part of cardiac surgical practice. This review provides a summary of the patency rates, technical features and certain characteristics of the venous conduits. It also examines the current understanding and knowledge of venous histology, vein graft pathology and the associated endothelial and smooth muscle cell physiology and pharmacology. In addition, the existing and the emerging strategies to combat and control vein graft intimal hyperplasia and accelerated atherosclerosis are reviewed in detail.     

冠状动脉旁路移植术静脉移植物内膜增生的治疗策略

尽管冠状动脉旁路移植术中动脉桥血管被广泛使用且远期通畅率高,但大隐静脉移植物仍是冠状动脉旁路移植术使用最多的桥血管,而大隐静脉移植物术后10年通畅率大约60%。静脉移植物再狭窄的机制包括血栓形成、心内膜增生和粥样硬化等。防治静脉移植物再狭窄的方案包括药物治疗、基因治疗和血管外支架。现就上述治疗方案作一综述。     

Scoring system for predicting saphenous vein graft patency in coronary artery bypass grafting

The initial and long-term benefits of coronary artery bypass grafting depend upon maintaining the coronary blood flow supplied by the graft. In order to devise a scoring system for predicting graft patency, we evaluated presumptive correlations between saphenous vein graft patency and the characteristics of saphenous veins that were used as conduits in coronary revascularization.We prospectively evaluated 1,000 saphenous vein segments that were implanted in 403 consecutive patients who underwent on-pump coronary artery bypass grafting at our hospital from January 2006 through February 2009. Branches, varicosity, diameter, and wall thickness were evaluated, and a scoring system was created in order to obtain a value for each characteristic. The patients were postoperatively monitored for 1 year, and graft patency was then evaluated with the use of 64-slice multidetector computed tomography.Lesions were found in 12.3% of the grafts. All of the evaluated characteristics of the grafts had a significant correlation with saphenous vein graft flow (P <0.0001). Using the venous characteristics in our statistical analysis, we devised a formula to obtain a score (range, 4-12) to predict the patency of each graft. A cutoff score of 7 yielded 87.8% sensitivity and 82.8% specificity.Our scoring system has good prognostic value. We believe that it can assist surgeons in choosing the most appropriate conduit and target vessel for coronary artery bypass grafting, especially in high-risk patients who are particularly dependent on blood flow through saphenous vein grafts.     

Arterial conduits update

Arterial grafting for coronary artery disease has been practiced routinely at the Epworth Hospital for 20 years. Bilateral versus single internal thoracic artery grafts is associated with improved survival, which progressively increased over the 20 years of post-surgery. The average increase in survival was 15% at 20 years. The question of whether to use the radial artery or the saphenous vein graft as supplementary grafts remains unanswered. Current patency data suggest that there is a marginal advantage of radial artery over saphenous graft patency, particularly between 5 and 10 years after surgery. However, there appears to be improved patency of the saphenous vein when used as a coronary artery bypass with the advent of aspirin, lipid-lowering and anti-hypertensive therapy.     

预防静脉桥再狭窄的基因治疗研究现状

在外科治疗动脉狭窄或闭塞性疾病中,应用静脉移植使血管重建是一种常用的方法,其中,在冠状动脉疾病中应用较为广泛,尤其是应用自体大隐静脉进行冠状动脉旁路移植手术。短期内其效果非常有效,但远期通畅率欠佳,尽管有一定的预防方法,但是效果不太理想,而基因治疗作为其中的一项,成为一个潜在的治疗选择。基因治疗可以通过减少血栓形成、血管内膜增生、动脉粥样硬化进而改善桥血管通畅率,本文我们将对预防静脉桥再狭窄的基因治疗做一综述。     

Effect of obesity on saphenous vein graft stenosis in patients with postoperative recurrent angina

BACKGROUND: Coronary artery bypass surgery with saphenous vein grafts is a well accepted treatment method of coronary artery disease despite the diminishing patency rates of saphenous vein grafts over time mainly due to the atherosclerotic process. Obesity has been shown to be a risk factor for coronary artery disease, but the impact of obesity on saphenous vein graft patency is less well described. This study was designed to examine the effect of obesity on the early and late saphenous venous graft stenosis. METHODS: 676 consecutive patients (mean age 62.9 +/- 9.7 years), undergoing a first-time coronary angiography after bypass surgery for recurrent angina were evaluated: body mass index was measured for 323 patients with at least one saphenous vein graft stenosis (group I) and 353 patients without saphenous vein graft stenosis (group 2). RESULTS: There were no statistically significant differences in terms of hypertension, diabetes, smoking, hyperlipidaemia and gender as well as body mass index (BMI) status of the patients between the two groups (P > 0.05). The patients in both groups divided into obese and non-obese subgroups using a definition for obesity of BMI < or =30 and cumulative saphenous vein graft patency rates were evaluated as a function of time. Kaplan Meier curves showed that obese and non-obese patients had similar patency rates according to time since coronary artery bypass surgery (P > 0.743). CONCLUSION: Body mass index seems not to have an impact on the early and late saphenous venous disease in a group of consecutive patients admitted with recurrent angina.     

Saphenous vein graft vs. radial artery graft searching for the best second coronary artery bypass graft

Coronary artery bypass grafting (CABG) was first used in the late 1960s. This revolutionary procedure created hope among ischemic heart disease patients. Multiple conduits are used and the golden standard is the left internal mammary artery to the left anterior descending artery. Although all approaches were advocated by doctors, the use of saphenous vein grafts became the leading approach used by the majority of cardiac surgeons in the 1970s. The radial artery graft was introduced at the same time but was not as prevalent due to complications. It was reintroduced into clinical practice in 1989. The procedure was not well received initially but it has since shown superiority in patency as well as long-term survival after CABG. This review provides a summary of characteristics, technical features and patency rates of the radial artery graft in comparison with venous conduits. Current studies and research into radial artery grafts and saphenous vein grafts for CABG are explored. However, more studies are required to verify the various findings of the positive effects of coronary artery bypass grafting with the help of radial arteries on mortality and long-lasting patency.     

Radial artery conduit for coronary revascularization: as good as an internal thoracic artery?

PURPOSE OF REVIEW: Multiple arterial grafting has been proposed to improve outcomes after coronary bypass surgery. We sought to define the emerging role of the radial artery as an alternative second arterial graft. RECENT FINDINGS: Despite significant evidence suggesting superiority of bilateral internal thoracic artery grafting, utilization in current clinical practice remains low due to concerns about sternal wound infection and conduit length. Recent clinical trials have started to clarify the role of the radial artery in coronary surgery. This conduit provides superior patency to saphenous vein grafts in the setting of high-grade stenosis regardless of the target territory and with minimal harvest site complications. SUMMARY: The radial artery is a versatile conduit that provides clinical benefit in a large variety of patients undergoing coronary bypass surgery. Outcomes from ongoing longitudinal clinical trials will further clarify optimal conduit selection strategies.     

IVUS-controlled aorto-ostial directional coronary atherectomy in higher grade stenosis of the central anastomosis of a sequential triple venous bypass

Following coronary artery bypass grafting repeat ischemia mandatory for reintervention occurs in 2 to 30% of cases, depending mainly on graft age. Selection of a suitable strategy for revascularisation--transcatheter angioplasty or reoperation--depends on various parameters including coronary morphology, left ventricular performance, comorbidity and availability of graft material. Catheter-based interventions on saphenous vein bypass grafts are feasible, but lower primary success rates and a higher incidence of restenosis--compared with native coronary arteries--have to be expected. Repeat coronary artery bypass graft operations are associated with a significantly higher perioperative morbidity and mortality, patency rates are lower and late clinical outcome is worse than in primary surgery. We report on a patient who underwent coronary artery bypass grafting 4 years ago revealing a high grade ostial stenosis in a jump-graft supplying RCA, LAD and Cx sequentially, making reintervention necessary. As a prerequisite serial balloon angioplasty of two native vessels was performed prior to ostial intervention. Intravascular-ultrasound guided directional coronary atherectomy was performed with good primary and long-term result. Our case demonstrates that, if all relevant clinical parameters and different therapeutic options are taken into account, complex transcatheter angioplasty procedures are feasible and associated with a reasonable amount of risk, thus avoiding repeat coronary artery bypass graft operations.     

Long-term results of coronary artery bypass grafting

Coronary artery bypass grafting has been an established procedure for more than 20 years. This article summarizes recently published information regarding the long-term results of coronary artery bypass grafting, including several analyses of large data bases that extend over periods of 15 to 20 years. Other research pertinent to the etiology of conduit occlusion and information regarding the management of patients with recurrent ischemia following coronary artery bypass grafting is discussed. The studies reviewed for the present article confirmed the beneficial effect of internal mammary artery grafting on long-term survival and defined the factors influencing long-term survival in patients with saphenous vein grafts. Other studies determined the effect of initiating aspirin postoperatively on graft patency, evaluated novel conduits for grafting, and elucidated the remodeling of saphenous vein that occurs over time in the arterial circulation.     

Evaluation of Previously Cannulated Radial Arteries as Patent Coronary Artery Bypass Conduits

In coronary artery bypass grafting, good-quality conduits are needed to maximize the potential for long-term patency. Revascularization has traditionally been achieved with use of the saphenous vein and the internal thoracic arteries. In recent years, total arterial revascularization with use of the radial arteries has been promoted. Meanwhile, use of the transradial approach for coronary angiography has also increased. The long-term effects of previous cannulation in radial artery bypass grafts are not known. Therefore, we used multidetector computed tomographic angiography to investigate radial-artery graft patency in a small series of patients who had undergone transradial angiography. We found a high patency rate, and we discuss those findings here.     

Individual Versus Sequential Saphenous Vein Grafts for on-Pump Coronary Artery Bypass Grafting – Does Smaller Coronaries in Indians Affect Graft Choice? – A Mid-Term Patency Comparison Study

PurposeAlthough multiarterial grafting or bilateral mammary artery use is being increasingly emphasized for contemporary coronary artery bypass grafting (CABG) practice, saphenous vein graft (SVG) still accounts for 80% of all CABG conduits (Park et al., 2020) [1]. In India, both the individual and sequential saphenous grafting techniques are used arbitrarily, and there has not been a study that compares the mid-term patency of these two. This is specially relevant in view of smaller coronaries in Indians than the Caucasian counterparts. This study aims to compare the patency for on pump CABG’s.MethodsIn the present study, 323 patients underwent either sequential (group A, N = 151 grafts, each graft having two anastomoses each) or individual (group B, N = 344 grafts) saphenous vein CABG, between February 2014 and June 2017. The SVG anastomoses were created on obtuse marginal (OM1/OM2) and posterior descending artery (PDA). The graft patency of the vein grafts as well as the left internal mammary artery were assessed by serial coronary angiograms.ResultsResults were evaluated at 6 months, 1, 2 and 3 years post operatively. Group A showed a higher graft patency at 3 years at 80.8%, and group B, 67.1% (P = 0.002). Also, anastomoses on sequential conduits had overall better patency rates at three years (77.2% vs 67.2%, P = 0.005). The groups showed similar results at one year post operatively.ConclusionsSequential bypass grafts were associated with superior mid-term patency compared with individual grafts. These findings suggest the more favourable results of sequential bypass grafting to be attributed to the enhanced flow haemodynamics.     

Current status of endoscopic vein harvest in cardiac and peripheral vascular surgery

Endoscopic harvesting of the saphenous vein (EVH) has been shown to minimize the morbidity associated with saphenous vein harvest for either coronary artery bypass or lower extremity bypass. However, the long-term benefit of a bypass procedure is predicated on conduit patency. Several studies suggest decreased patency with EVH compared with open vein harvest. Possible reasons for this discrepancy have been investigated by microscopic, electron microscopic, and functional studies of venous endothelium and contractile function of harvested veins with conflicting results. This review details the results of these studies. In addition, the clinical results of coronary bypass graft and lower extremity bypass with open vein harvest and EVH are described in regard to early wound complications and short- and long-term patency.     

The future of saphenous vein as a coronary artery bypass conduit

Continuing widespread use of autologous saphenous vein for coronary artery bypass grafting seems unavoidable despite its poor-term patency. We review here the evidence that platelet activation is responsible for early and late vein graft occlusion and conclude that other mechanisms probably contribute to late occlusions. We suggest that a rational strategy to improve vein graft patency should include: improved endothelial preservation during surgical implantation; use of better antiplatelet agents, in particular those which prevent platelet adhesion as well as aggregation; reduction of risk factors including serum cholesterol; and application of agents (e.g. heparin) which inhibit smooth muscle cell proliferation directly. We draw parallels between the pathogenesis of vein graft occlusion and coronary atherosclerosis and suggest that testing strategies for improving vein graft patency may also shed light on atherogenesis.     

Acute anterior myocardial infarction due to aortosaphenous vein graft occlusion with very large thrombus burden

A 75-year-old man, with a previous history of myocardial infarction and three-vessel coronary artery bypass grafting, presented with an acute anterior ST-elevation myocardial infarction. The vein graft to the left anterior descending artery was occluded with heavy thrombus burden, and the other grafts were patent. After administering a bolus dose of tirofiban and then undergoing percutaneous coronary intervention without stenting to the left anterior descending artery saphenous vein graft, intracoronary thrombolytic infusion was performed to maintain the patency of the vein graft. The patient was asymptomatic after medical follow-up. This may be an effective treatment option in patients with large thrombus burden and requires further investigation through large-scale trials.     

Percutaneous treatment of saphenous vein graft aneurysm: Contemporary procedural considerations

While coronary artery bypass grafting remains an essential component of revascularization therapy, the use of venous conduits in the form of saphenous vein grafts is associated with a number of late sequelae, including graft stenosis and occlusion. The recognition of saphenous vein graft aneurysm, typically a late complication, may be associated with adverse outcomes. We describe the percutaneous therapy of saphenous vein graft aneurysm, utilizing contemporary devices, including newer generation covered stents, and the use of devices more commonly used in peripheral vascular intervention, reflecting the dilated nature of vein grafts. Saphenous vein graft aneurysm can be successfully treated with percutaneous therapy, avoiding the risk of repeat sternotomy and associated morbidity. The use of new generation covered stents has not been previously well reported; however, it may have an important role in the treatment of coronary artery and saphenous vein graft aneurysm. Awareness of the role of covered stents used in both coronary and peripheral intervention and the advantages of new generation devices are essential to allow optimal therapy of this uncommon, late complication. The role and potential benefits of new generation covered stents are discussed with a review of the existing literature.     

Intraarterial digital subtraction angiography for evaluation of internal mammary artery graft in coronary bypass surgery

Digital subtraction angiography (DSA) was performed to evaluate graft patency in 60 patients who had undergone coronary artery bypass grafting with the internal mammary artery (IMA). Sixty IMA grafts with 62 distal anastomoses, and 84 saphenous vein grafts with 85 distal anastomoses were evaluated by intraarterial DSA with an image frequency of 4 frames/sec. A No. 4 Fr. angiography catheter was introduced percutaneously into the left brachial artery and contrast medium was injected both into the subclavian artery for opacification of the IMA grafts and into the ascending aorta for opacification of aortocoronary saphenous vein grafts. Bypass grafts were defined as patent when grafts were opacified through their entire course, including anastomotic sites. Fifty-nine IMA grafts with 61 distal anastomoses (98%) and 76 saphenous vein grafts with 77 distal anastomoses (91%) were patent. The overall patency rate for total grafts was 94%. In 4 patients, DSA showed a "string sign" in the IMA graft which was patent but narrowed at its distal segment. In 5 patients, large first intercostal branches were opacified. Intraarterial DSA with the retrograde brachial approach is not difficult, and is an excellent low risk method of evaluating the patency of IMA and saphenous vein grafts. DSA provided information about functional patency as well as anatomical patency of the IMA graft.     

冠状动脉旁路移植术后静脉移植物内膜增生的发病机制

动脉桥管在冠状动脉旁路移植术中广泛使用且明显提高了远期效果,但静脉移植物仍然是使用最多的桥管.研究表明静脉移植物10年通畅率约为60%.静脉移植物再狭窄发病机制包括血流动力学变化导致血管壁受损,血栓形成和血管平滑肌迁移、增生,以及随后发生动脉粥样改变等.本文就静脉移植物再狭窄的发生机制作一综述.     

Antithrombotic therapy in the coronary vein graft patient

Coronary artery bypass grafting is an important therapeutic modality in the treatment of the patient with coronary artery disease; however, long-term results are limited by the development of saphenous vein graft disease early and late after operation. The pathogenesis of early vein graft occlusion is primarily thrombotic, while that occurring later frequently involves thrombosis superimposed on intimal hyperplasia or vein graft atherosclerosis. We describe the role of various platelet inhibitors and anticoagulants in the prevention of saphenous vein graft occlusion following coronary artery bypass grafting.