Initial experience with sequential internal mammary artery bypass grafts to the left anterior descending and left anterior descending diagonal coronary arteries

Early patency and late patency have consistently been better with single internal mammary artery grafts than with saphenous vein conduits. To determine the efficacy of these two types of grafts in sequential anastomoses, we performed sequential anastomoses of the left internal mammary artery to the left anterior descending and diagonal coronary arteries in 40 patients and compared the results with those in 58 patients who received sequential saphenous vein grafts. Treatment with dipyridamole (starting 48 hours before operation) and aspirin (added 7 hours after operation) was given to the 40 patients with internal mammary artery grafts and to 32 of the 58 patients in the saphenous vein group. After the bypass procedure, mean blood flows were as follows: 68 ml/min in patients with internal mammary artery grafts, 73 ml/min in patients who received saphenous vein grafts and a placebo, and 99 ml/min in those who received saphenous vein grafts, aspirin, and dipyridamole. Early patency of sequential internal mammary artery grafts to the diagonal and left anterior descending coronary arteries was comparable to that of sequential saphenous vein grafts. Because a substantial late reduction in patency has been noted in sequential saphenous vein grafts, sequential internal mammary artery grafts may be the preferred conduit for coronary artery revascularization.     

THE LIMA SUCCESS STORY — WHITHER OTHER ARTERIAL GRAFTS — ARE VEIN GRAFTS OBSOLETE ?

SUMMARY The long-term benefit of myocardial revascularisation depends largely upon the continued patency of bypass grafts, but the long-term patency of vein grafts is poor. To improve the results of myocardial revascularisation, either measures to increase the patency of saphenous vein grafts or alternative conduits are required. Use of the left internal mammary artery as a graft is known to increase survival, and this has prompted wider use of other arterial grafts in the expectation that they will further enhance the long-term results of coronary artery bypass. This policy is based upon sound theory, but convincing evidence that it improves survival is lacking. Meanwhile, advances in the understanding of the pathology of vein graft occlusion have given rise to new methods of increasing vein graft patency. While these techniques are, as yet, only experimental, if translated into clinical practice, the places of arterial and venous grafts may require further assessment.     

Reoperative off-pump coronary artery bypass grafting: current outcomes,concerns and controversies

Increasing numbers of patients have undergone coronary artery bypass grafting in the last four decades. As a result, the incidence of reoperative coronary artery bypass grafting is rising. Reoperative procedures pose several technical difficulties and are associated with increased operative risks, which exceed those of the initial revascularization. As the incidence of reoperative procedures is increasing so is the experience of reoperative coronary artery bypass grafting, with the resultant evolution of several alternative strategies to lower the operative risks. These strategies include alternative techniques for re-entry, strict avoidance of graft manipulation to minimize the risk of graft atheroembolism, and modification of the method of myocardial protection, depending on the status of the native coronary circulation and the patency of venous or arterial grafts. Off-pump coronary artery bypass grafting is one such technique that, through the avoidance of inherent risks of cardiopulmonary bypass, has the potential to reduce the morbidity associated with reoperative coronary artery bypass grafting. This article evaluates the current outcomes of reoperative off-pump coronary artery bypass grafting, and highlights the concerns and controversies associated with this strategy.     

CT血管造影分析体外循环与非体外循环冠状动脉旁路移植后的桥血管通畅率

背景：近年来,非体外循环冠状动脉旁路移植后桥血管通畅率是否与传统的体外循环冠状动脉旁路移植相同存在争议。目的：探讨体外循环与非体外循环冠状动脉旁路移植后桥血管时间通畅率的差异性。方法：选取同一操作者行体外循环冠状动脉旁路移植患者100例,按其临床特征及桥血管病变危险因素匹配抽取非体外循环冠状动脉旁路移植患者137例。采用64排多螺旋CT血管造影分析冠脉搭桥后1个月,1年,2年,3年,4年的桥血管通畅情况。结果与结论：共对641条桥血管进行评价,两组中左侧乳内动脉桥血管时间通畅率均高于大隐静脉桥,两组左侧乳内动脉桥和大隐静脉桥血管时间通畅率比较差异均无显著性意义。说明非体外循环与体外循环冠状动脉旁路移植后患者桥血管时间通畅率相似,对于某些适当的患者来说,非体外循环冠状动脉旁路移植不失为一个良好的选择。     

Vein graft failure: current clinical practice and potential for gene therapeutics

Autologous saphenous vein is commonly used as a conduit to bypass atherosclerotic lesions in coronary and femoral arteries. Despite the wide use of arterial conduits, which are less susceptible to complications and failure, as alternative conduits, the saphenous vein will continue to be used in coronary artery bypass grafting until acceptable alternative approaches are evaluated. Hence, preservation of vein graft patency is essential for the long-term success. Gene therapy is attractive in this setting as an ex-vivo technology to genetically manipulate the conduit before grafting. The use of safe and efficient vectors for delivery is a necessity as well as a strategy to improve patency in the long term. Here, we review the current clinical practice, the pathogenesis of bypass graft failure and adenovirus-mediated gene therapy strategies designed to improve late vein graft failure by modulation of smooth muscle cells in the vein wall.     

Intraoperative assessment of coronary grafts by novel digital epivascular imaging.

OBJECTIVE: We sought to validate and evaluate 2 novel intraoperative ultrasound probes for epicoronary and epiaortic imaging. BACKGROUND: The noninvasive intraoperative assessment of successful coronary artery bypass grafting remains a challenge. METHODS: A total of 19 consecutive patients (4 female, 15 male; mean age 60.5 +/- 13.8 years SD, range 34-84) underwent coronary artery bypass grafting. The epivascular probes (GE Ultrasound) were validated in vitro and intraoperatively. Coronary arteries, grafts, and ascending aorta were imaged and quantified. RESULTS: Mean adjusted flow measured by flowmeter was 3.25 L, SE 0.47 (range: 1-5.5 L) and was 3.15 L, SE 0.46 (range: 1-5.0 L) by ultrasound, with r = 0.97, P <.0001. Intraoperatively, 56 native coronary vessels were bypassed using 15 left internal mammary artery grafts, 25 vein grafts, and 16 venous jump grafts. A total of 15 left internal mammary artery grafts (100%), 12 left internal mammary artery anastomoses (80%), 20 vein grafts (15 left anterior descending coronary arteries, left circumflex artery grafts, 5 right coronary artery grafts) (80%), 4 jump grafts (25%), and 15 ascending aortas (78%) were successfully imaged by inexperienced surgeons. Doppler flow measurements were possible in 50 vessels (89%). Mean lumen diameter for graft arteries (veins) was 2 mm (2.87 mm), maximal velocity was 72 cm/s (46 cm/s), and mean velocity was 29 cm/s (21 cm/s) with a mean flow rate of 70 mL/m (55 mL/m). CONCLUSIONS: We conclude that: (1) the novel intraoperative probes measure validated flow; (2) intraoperative hemodynamic assessment of graft patency is feasible without a learning curve; and (3) these findings should encourage the routine use of these intraoperative epivascular digital ultrasound probes.     

Technical considerations in aortocoronary bypass grafting

Since the inception of aortocoronary bypass surgery, many technical advances have been rapidly achieved. Early experience was limited to reversed saphenous vein grafting of single vessel coronary artery disease. Multiple grafts to several vessels soon became commonplace and sequential grafting techniques were developed. Expanded use of the internal mammary artery resulted after analysis of superior patency rates achieved with this conduit. Use of alternative conduits such as upper extremity veins, allogenic veins, synthetic graft material (polytetrafluorethylene), radial artery, splenic artery, and gastroepiploic artery have been explored. Apart from the gastroepiploic vessel, none of these alternative conduits have been suitable. A grat deal of effort has been directed at the mechanisms of saphenous vein occlusion including technical considerations, early thrombosis, intimal hyperplasia and graft atherosclerosis. Platelet inhibition and lipid reduction have shown promise in improving patency rates. Further work in these areas should lead to even better results.     

The statistical analysis of graft patency data in a clinical trial of antiplatelet agents following coronary artery bypass grafting

Because most coronary artery bypass patients receive more than one graft at surgery, it is most important to determine whether statistical analysis of graft patency should be performed on the premise that the multiple grafts within patients are dependent or independent experimental units. Veterans Administration Cooperative Study No. 207 was a multicenter clinical trial comparing four different antiplatelet regimens to placebo in the prevention of graft occlusion following coronary artery bypass grafting. Using the results from the 1-week postoperative angiograms from the Veterans Administration Cooperative Study No. 207, in which there were 3.2 distal anastomoses per patient, we have tested the hypothesis that grafts within patients tend to act dependently with respect to patency or occlusion by comparing the graft patency data to a binomial distribution (i.e., that distribution that would have been manifest if grafts were independent). Because the graft patency results in Study No. 207 significantly deviated from the binomial distribution (p = 0.0003), a more appropriate analysis for graft patency data was applied using a ratio estimate as applied to cluster sampling. The statistical methods used in 11 previous clinical trials of antithrombotic therapy after coronary artery bypass grafting were examined. Only one of the previous studies used such an analysis, and three additional reports attempted to correct for dependency of grafts within patients in their analyses using other statistical methods. In seven of the studies the investigators did not address the potential problem of a dependent relationship between multiple grafts within patients. We conclude that grafts within patients act as dependent experimental units and that the ratio estimate as applied to cluster sampling may be appropriately applied to these data.     

What has happened to multiple arterial grafting in coronary artery bypass grafting surgery?

Coronary artery bypass grafting (CABG) is a well-established therapy for patients with multivessel coronary artery disease, with excellent short- and medium-term results. This is best illustrated by studies comparing percutaneous coronary interventions (PCIs) with CABG surgery, where CABG continues to offer better event-free survival. However, there has been increasing concern about the long-term patency of vein grafts utilized for CABG when compared with arterial grafts. Some have suggested that revascularization with arterial grafts rather than vein grafts may result in improved outcomes following CABG. This is particularly important when one considers that graft occlusion can result in recurrence of disabling angina, rehospitalization, reintervention and death. To date, however, multiple arterial grafts have yet to become the standard approach for patients undergoing CABG. This is best exemplified by reports from large registries suggesting that the use of multiple arterial grafting is limited to approximately 10% of all patients undergoing CABG. In this article, we will provide some of the evidence outlining the risk and benefits of multiple arterial grafting, but more importantly, begin to explore why the utilization of multiple arterial grafting does not appear to be increasing significantly.     

心脏镜多支冠状动脉搭桥术的动物实验研究

目的探讨心脏镜即不需辅助小切口的完全内镜下多支冠状动脉搭桥术术式的可行性。方法实验动物为2头猪和24条狗,胸壁打孔,进行多支冠状动脉搭桥手术的操作。结果经过1.5cm的3、4个小孔可以完成右冠状动脉、左冠状动脉、前降支、对角支及回旋支等多支冠状动脉的搭桥手术,并能顺利完成左锁骨下动脉、降主动脉的远端吻合口的吻合操作。结论心脏镜多支冠状动脉搭桥术切实可行,值得进一步研究。不久的将来有可能成为心脏搭桥术的主要术式。     

Percutaneous transluminal coronary angioplasty and the changing indications for coronary artery bypass grafting for single-vessel coronary artery disease.

Patients with single-vessel coronary artery disease have a good long-term prognosis with either medical or surgical therapy. Because percutaneous transluminal coronary angioplasty has become widely available for treating patients with symptomatic single-vessel coronary artery disease, those who currently undergo coronary artery bypass grafting may be a select group. In this study, we examined the effects of the increasing use of percutaneous transluminal coronary angioplasty on the indications for coronary artery bypass grafting in patients with symptomatic single-vessel coronary artery disease and reviewed the type of procedures performed in such patients at our institution between 1983 and 1988. During this period, 115 patients underwent coronary artery bypass grafting for single-vessel coronary artery disease. The indication for revascularization was angina in 111 patients (88% were in class III or IV, Canadian Cardiovascular Society classification), acute myocardial infarction in 3, and a strongly positive result of an exercise test in 1. The number of surgical revascularization procedures annually for single-vessel coronary artery disease remained consistent throughout the study period. In a comparison of the first 3 years of the study with the last 3 years, the number of patients who underwent coronary artery bypass grafting for restenosis after coronary angioplasty increased, but the number who had surgical revascularization because of failure of coronary angioplasty decreased. In addition, more patients received internal mammary grafts during the second half of the study (42 or 72%) than during the first half (24 or 42%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Gene therapy and coronary artery bypass grafting: current perspectives

The early success of coronary artery bypass grafting (CABG) is limited by disappointing long-term patency rates of autologous saphenous vein grafts. Because current pharmacological interventions have only limited impact on vein graft patency rates, there remains a clear clinical need for effective agents to prevent failure of vein grafts in the long term. Gene therapy in vein grafts has great potential as gene delivery can be achieved ex vivo at the time of cardiac surgery, allowing transgene expression to occur rapidly post-grafting within the acute phase of vein graft remodelling. A variety of therapeutic strategies have been tested in a range of preclinical models, although to date, these have not advanced to Inhuman trials, except in the setting of adjunctive angiogenesis for improved revascularization (phase 1). Clinical translation is warranted to investigate the potential of gene therapy to improve CABG patency rates in the long term.     

CT血管造影分析体外循环与非体外循环冠状动脉旁路移植后的桥血管通畅率

背景:近年来,非体外循环冠状动脉旁路移植后桥血管通畅率是否与传统的体外循环冠状动脉旁路移植相同存在争议.目的:探讨体外循环与非体外循环冠状动脉旁路移植后桥血管时间通畅率的差异性.方法:选取同一操作者行体外循环冠状动脉旁路移植患者100例,按其临床特征及桥血管病变危险因素匹配抽取非体外循环冠状动脉旁路移植患者137例.采用64排多螺旋CT血管造影分析冠脉搭桥后1个月,1年,2年,3年,4年的桥血管通畅情况.结果与结论:共对641条桥血管进行评价,两组中左侧乳内动脉桥血管时间通畅率均高于大隐静脉桥,两组左侧乳内动脉桥和人隐静脉桥血管时间通畅率比较差异均无显著性意义.说明非体外循环与体外循环冠状动脉旁路移植后患者桥血管时间通畅率相似,对于某些适当的患者来说,非体外循环冠状动脉旁路移植不失为一个良好的选择.     

双源CT对冠状动脉桥血管的评价

【目的】评价双源螺旋CT对冠脉搭桥术后桥血管开通的诊断价值。【方法】对57例冠状动脉搭桥术后的患者行双源螺旋CT冠状动脉成像检查。【结果】所有141支桥血管均重建成功。其中内乳动脉桥39支,大隐静脉桥102支,通畅的桥血管102支（72．3％）,不同程度狭窄15支（10．63％）,完全闭塞24支（17．02％）。39支内乳动脉桥支33支通畅（84．62％）,102支大隐静脉桥支69支通畅（67．65％）,两种桥血管间相比较差异显著（P〈0．05）。【结论】双源螺旋CT是评价冠状动脉搭桥术后桥血管开通的有价值的无创检查方法。     

Use of the internal mammary artery for myocardial revascularization in a patient with radiation-induced coronary artery disease.

A 9-year-old boy with clinical stage IIA Hodgkin's disease underwent radiotherapy to the neck and mediastinum. Twenty-two years later, he sought medical attention because of angina pectoris. Cardiac catheterization revealed proximally located high-grade stenoses of the left main, left anterior descending, circumflex, and right coronary arteries. He underwent coronary artery bypass grafting with use of the left internal mammary artery to the left anterior descending coronary artery and reversed saphenous vein grafts to the circumflex and right coronary arteries. The postoperative course was uncomplicated. Previous radiotherapy to the mediastinum should be considered a risk factor for the development of premature coronary artery disease. Surgical revascularization is the preferred method of management. A combination of an internal mammary artery graft and a saphenous vein graft should be used in young patients.     

Repeat myocardial revascularization for uncontrollable angina after occlusion of prior aortocoronary bypass.

Twelve patients at Emory University Hospital have had repeat myocardial revascularization for recurrent, uncontrollable, disabling angina pectoris after previous coronary artery bypass grafts. The interval betweeen initial bypass procedure and reoperation ranged from six weeks to six years. The native coronary circulation remained unchanged in six, had developed additional proximal (left main) obstruction in four, and had advanced stenosis at the site of former anastomosis in three. Repeat revascularization consisted of new vein graft construction in eight and vein and internal mammary artery graft in four, with an average of 1.9 grafts per patient. There were no deaths. Seven of 12 patients (60%) are now asymptomatic and three of 12 (25%) are significantly improved. Patency of new grafts studied by elective repeat coronary angiography in six patients showed patency of all grafts to the left anterior descending artery and four of six grafts to other vessels. Analysis of the initial graft closures, method for selecting patients to undergo a second procedure, and operative technics believed important in safety of reoperation and avoidance of repeat early graft occlusion are presented.     

升主动脉No—touch技术在冠心病手术中的应用

目的探讨和评价升主动脉不接触技术（No—touch）在冠状动脉旁路移植手术中的应用。方法回顾5例合并升主动脉粥样硬化冠心病患者的临床资料,男3例,女2例,年龄68--76岁,平均70．2岁。5例均采用常规胸骨正中切口行非体外循环下冠脉搭桥（OPCABG）。2例行双侧乳内动脉原位移植,3例以左乳内动脉为唯一的供血来源,大隐静脉近端与左乳内动脉端侧吻合。所有患者未在升主动脉上进行任何操作。结果5例患者共移植血管13支,全组手术均顺利完成,痊愈出院,无院内死亡。手术后所有忠者心绞痛均消失,心功能改善I～II级。无围术期心肌梗死和神经系统并发症发生。结论对合并升主动脉粥样硬化的冠心病患者,采用OPCABG结合升主动脉不接触（No—touch）技术,可使病变冠脉完全再血管化,降低术后脑卒中的发生率,临床效果满意。     

Developments in surgical revascularization to achieve improved morbidity and mortality

Coronary artery bypass graft surgery remains the main treatment modality for multivessel coronary artery disease and has consistently been demonstrated to have significantly lower rates of major adverse cardiac and cerebrovascular events in comparison to percutaneous coronary intervention. In this article we will explore the advances over time and the recent refinements in the techniques of surgical revascularization and how these contribute to the superior outcome profile associated with coronary artery bypass graft surgery. These include the current outcome status of coronary artery bypass grafting; the major landmark trials, registries and meta-analyses comparing coronary artery bypass grafting and percutaneous coronary intervention; the developments in coronary artery disease lesion classification; the techniques for the physiological assessment of coronary artery lesions; bypass grafting using arterial conduits; the role of off-pump coronary artery surgery; the outcomes of reoperative surgery; hybrid techniques for coronary revascularization; minimally invasive coronary artery surgery and finally robotic surgery.     

Gene therapy for human bypass grafts

Autologous saphenous vein is the conduit of choice for the bypass of arterial occlusive disease, be it in the peripheral arterial tree or in the coronary system. This technique is limited by primary graft failure rates approaching 20% in the first year for peripheral arterial disease and 50% at 10 years for coronary artery bypass grafting. The PREVENT trial describes a novel, safe and effective means of ex vivo transfection of harvested vein grafts with an E2F decoy oligonucleotide, with 70-74% decreases in the level of proliferating cell nuclear antigen (PCNA) and c-myc mRNA expressed by the smooth muscle cells in the vein. This translated into a statistically significant reduction in primary graft failure when used to bypass peripheral arterial occlusions in a high-risk human patient population.