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。     

Multicenter radial artery patency study (RAPS). Study design

The use of an internal thoracic artery rather than a saphenous vein graft for left anterior descending coronary artery bypass is associated with improved long-term outcome. Hence, expanded use of arterial conduits for other coronary targets has been advocated. The radial artery possesses a number of anatomic features that are technically advantageous compared with other arterial conduits. This study will determine the relative patency of the radial artery compared to the saphenous vein for right and circumflex coronary bypass. Patients with graftable multivessel coronary disease and an estimated left ventricular ejection fraction >/= 35% undergoing nonemergent primary isolated coronary bypass surgery are eligible. The right and circumflex vessels must have high-grade lesions (>/= 70% diameter stenosis), with target segments of reasonable quality >/= 1.5 mm in diameter. Patients serve as their own controls. The radial artery is randomly allocated to bypass the right or circumflex territory and a saphenous vein is used for the nonradial site. An internal thoracic artery is used for the left anterior descending coronary artery in all cases. Randomization is stratified by center. The primary study endpoint is graft patency as determined by angiography, 8-12 months postoperatively. The relative patency of the radial artery compared with the saphenous vein will be determined using McNemar's test. A sample size of 464 patients will provide 80% power for a two-tailed test (alpha = 0.05) for a 40% relative reduction in the rate of distal anastomotic occlusion from 12% in the saphenous vein to 7.2% in the radial arteries assuming a 20% within-patient correlation. A single interim analysis will be performed following completion of 232 angiograms. To allow for lack of follow-up angiography in up to 20% of enrolled patients, we plan to randomize a total of 560 patients. It is also our intention to assess the long-term patency (5-10 years) of radial artery relative to saphenous vein grafts in follow-up studies. Three hundred patients were recruited from 12 Canadian, university-affiliated sites from November 1996 until February 1999, of which 128 patients have undergone follow-up angiography. Approximately 80% of those who have been followed for more than 1 year have undergone follow-up angiography. This trial will determine the 8-12 month patency of the radial artery relative to the saphenous vein for non-left anterior descending coronary bypass using a novel study design which helps control for potential bias from individual patient and vessel factors. Positive results would support the use of the radial artery in particular, and multiple arterial grafts in general.     

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.     

Echocardiographic diagnosis of an asymptomatic aneurysm of a saphenous vein graft.

A case of a 73-year-old asymptomatic man with a large saphenous vein graft aneurysm first diagnosed 16 years after bypass operation is presented. The lesion was first suspected on routine transthoracic echocardiography and further clarified by transesophageal echocardiography. Selective graft angiography confirmed the diagnosis and surgical therapy included resection of the graft aneurysm and coronary artery bypass grafting.     

常规超声结合冠脉血流显像技术评价冠状动脉搭桥术后桥血管通畅性

目的应用常规超声结合冠脉血流显像技术评价冠状动脉搭桥术后桥血管通畅性.方法行冠状动脉搭桥术(左乳内动脉原位转流至左前降支)患者46例;术后检查乳内动脉桥起始段、桥血管远段(吻合口近端)、吻合口、远端及近端左前降支.分别测量各段收缩期峰值流速、舒张期峰值流速、收缩期流速时间积分、舒张期流速时间积分.结果乳内动脉原位转流术后, 桥血管起始段显示率95.65%;桥血管与自体左前降支吻合口显示率80.43%.通过测量并计算吻合口与吻合口近端桥血管流速时间积分比值以及舒张期峰值流速比值评价吻合口是否存在狭窄.结论常规超声结合冠脉血流显像技术可提供评价桥血管通畅性的直接证据,为临床随访提供一种新的无创的方法.     

冠状动脉桥血管的多层螺旋CT和造影评价

目的:评价多层螺旋CT在显示冠状动脉桥血管中的临床应用价值。方法:21例冠状动脉血管旁路移植术后患者行多层螺旋CT血管成像及常规造影检查,分析CT诊断桥血管通畅性和狭窄的可靠性。结果:多层螺旋CT血管成像成功检测出21例患者共45支桥血管,15支桥血管闭塞,30支桥血管通畅,10支共16处狭窄,5支桥血管明显狭窄(>50%)8处,5支桥血管显示轻度狭窄(<50%)病变8处,MSCT评价桥血管闭塞和明显狭窄和导管造影完全符合。结论:多层螺旋CT尤其是64层CT能够准确地评价冠状动脉桥血管及吻合口的通畅性和狭窄情况,可以作为临床上对冠状动脉桥血管可疑病变的一种常规的无创性检查手段。     

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.     

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。     

Feasibility and diagnostic accuracy of 16-slice multidetector computed tomography coronary angiography in 500 consecutive patients: critical role of heart rate

Purpose To evaluate the feasibility and diagnostic accuracy of multidetector computed tomography coronary (MDCT) angiography applied to an unselected heart-disease population, to identify all causes of unfeasibility of exams, the distribution of artifacts in every coronary segment and their influence on diagnostic accuracy of examination. Materials and methods We evaluated 500 patients with different indications for invasive coronary angiography. All underwent coronary MDCT and ICA. 215 patients were pre-treated with metoprolol intravenously. In the whole population we studied native coronary arteries and in 141 cases the patency of coronary artery bypass grafts (CABG). The quality of MDCT images was graded as good, sufficient and insufficient. Results We were able to evaluate the patency of all grafts, with the exception of 4 cases. Diagnostic accuracy of CABG evaluation was very high (sensitivity 100%, specificity 98.4%). In native coronary arteries the overall feasibility was 97.9%. The middle left circumflex artery, right coronary artery and posterior descending artery were the segments most often poorly visualized. The first cause of artifacts was misalignment related to high heart rate, followed by premature heart beats and calcified plaque. The population was separated into 3 groups: group 1: heart rate <55 bpm, group 2: 55–65 bpm, group 3: >65 bpm. In group 1, misalignment was significantly lower than in groups 2 and 3. On a segment-based analysis, overall feasibility was therefore significantly higher in group 1 vs group 2 and vs group 3. Images of good quality were significantly higher in group 1 (95.4%) than in group 2 (87%) and group 3 (71.8%). The higher image quality in group 1 impacts on the overall diagnostic accuracy of the exam. Indeed overall sensitivity is significantly higher in group 1 (89.5%) than in group 2 (86%) and group 3 (82.8%) and overall specificity is significantly higher in group 1 than in group 3. Conclusions Multidetector computed tomography has a high feasibility and diagnostic accuracy for the evaluation of coronary artery disease in an unselected population. Good patient preparation (optimized beta-blocker therapy, correct breathing instructions) is essential for evaluating native coronary arteries while preparation with a beta-blocker is less relevant in bypass graft patients.     

Nonangiographic assessment of coronary artery bypass graft patency

Coronary artery bypass graft patency can be assessed using the indirect techniques of evaluating patients' symptoms and exercise tolerance, changes in stress electrocardiogram, radioisotope regional perfusion, and myocardial wall contraction. The direct techniques assess graft patency directly by visualizing grafts using conventional computed tomography (CT), ultrafast CT, magnetic resonance imaging, digital subtraction angiography, and echocardiography. The advantages and disadvantages of each of these modalities are reviewed. At the present time, ultrafast CT and possibly magnetic resonance imaging and Doppler appear to be the only techniques besides angiography that can consistently evaluate bypass graft patency. Although they have the advantage of being minimally invasive, they cannot show graft stenosis or sequential graft patency. These techniques are best used in following patients after coronary bypass graft surgery and ruling out graft closure as the source of chest pain.     

Coronary artery vasculitis: assessment with cardiac multi-detector computed tomography

Coronary artery vasculitis is rare and comprises an array of inflammatory diseases. It often results in severe and life-threatening complications, including coronary artery aneurysm, coronary artery stenosis, intraluminal thrombosis, and microcirculation abnormalities. These may occur at a young age and are often silent in the early phases. Invasive coronary angiography is the gold standard for diagnosing coronary artery disease (CAD); however, multi-detector computed tomography (MDCT) is now widely regarded as a powerful non-invasive tool for the detection of CAD. It is important for clinicians to recognize the various CT findings associated with coronary artery vasculitis in order to promote accurate diagnosis and proper patient management. The purpose of this article is to present an overview of the conditions associated with coronary artery vasculitis, with an emphasis on etiology and cardiac MDCT diagnosis of CAD. Cardiac MDCT is clinically useful and can provide information for the accurate diagnosis and treatment of coronary vasculitis.     

Intensive versus moderate atorvastatin therapy and one-year graft patency after CABG: Rationale and design of the ACTIVE (Aggressive Cholesterol Therapy to Inhibit Vein Graft Events) randomized controlled trial (NCT01528709)

RationaleSaphenous vein graft disease remains a major limitation of coronary artery bypass graft surgery (CABG). Statin therapy inhibits the development of vein graft disease and improves outcomes after CABG. However, it is unclear whether treatment with high-dose statins will further slow the process of vein graft disease and improve graft patency, as compared to conventional moderate doses. Therefore, the goal of this study will be to evaluate the efficacy of high-dose statin therapy versus moderate-dose statin therapy for the prevention of saphenous vein graft occlusion following CABG.Study designThe Aggressive Cholesterol Therapy to Inhibit Vein Graft Events (ACTIVE) trial is a multi-center double-blind randomized controlled trial enrolling patients who have undergone multi-vessel CABG with at least one saphenous vein graft. Patients will be randomized to receive either atorvastatin 80 mg daily or atorvastatin 10 mg daily for one year starting within 5 days after surgery. The target enrollment is 100 patients in each arm (200 patients total). Lipid levels will be assessed every 3 months. After one year, patients will undergo computed tomography (CT) coronary angiography to assess the incidence of vein graft occlusion and stenosis.ConclusionThis trial is the first prospective study to evaluate the impact of early postoperative high-dose statin therapy on graft patency after CABG. Should high-dose statin therapy reduce the incidence of postoperative graft occlusion, the results will add to the growing evidence supporting the role of high-intensity statins for modern lipid management after coronary surgical revascularization (ClinicalTrials.gov NCT01528709).     

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.     

下肢股腘动脉搭桥术中应用复合移植物6例报告

目的：为寻求一种有效的长距离膝下移植物来治疗下肢动脉长段阻塞或动脉旁路 远端动脉阻塞,方法：自１９９５年２月～１９９９年２月采用复合移植物治疗下肢股Ｕｕｏ动脉硬化闭塞症共６例,包括（１）“直接式”吻合法;（２）“跳跃式”吻合法;（３）“连贯式”吻合法：即先做膝上股Ｇｕｏ动脉人造血管移植。再做人造血管－自体大隐静脉－膝下Ｇｕｏ动脉端侧吻合。结果：经术后３年随访,６例中４例症状消失,２例症状同术前,结论：当无法应用单一的大隐静脉或人造血管时,复合移植物对治疗下肢股瘤动脉长段闭塞,特别是病变累及膝下动脉时,是合适的血管代用品。     

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.     

Coronary Artery Bypass Graft Imaging with 64-Slice Multislice Computed Tomography: Literature Review

Recurrent cardiac ischemia after coronary artery bypass graft surgery occurs in a significant proportion of patients, prompting repeat investigations and incurring significant clinical and financial costs. Noninvasive investigations to identify graft occlusion and quantify graft stenosis are desirable due to the complications, cost, and patient inconvenience of invasive coronary angiography. The increasing use of 64-slice multislice computed tomography has led to multiple reports on its accuracy in graft stenosis and occlusion. This review focuses on image acquisition and manipulation techniques, interpretative pitfalls, and the diagnostic performance of 64-slice multislice computed tomography in coronary artery bypass graft imaging across the medical literature.     

冠状动脉血流显像评价冠状动脉搭桥术后胸廓内动脉桥通畅性的研究

目的探讨冠状动脉血流显像技术评价冠状动脉搭桥术后胸廓内动脉桥通畅性的价值。方法对左胸廓内动脉一冠状动脉搭桥术并行桥血管造影术的9例患者进行随访，其中转流至左前降支者8例，转流至对角支者1例。3例因桥血管狭窄或闭塞于造影术中行左前降支近中段支架术。在冠状动脉造影前超声探测胸廓内动脉桥起始段、冠状动脉左前降支远段，分别测量各段收缩期峰值流速、舒张期峰值流速、收缩期流速时间积分、舒张期流速时间积分。评价桥血管通畅性，并与冠状动脉造影结果进行对照分析。行支架术患者于支架术后再行超声检查，观察上述参数变化。结果超声根据桥血管起始段频谱形态诊断桥血管通畅3例，狭窄3例，桥血管功能不良2例，闭塞1例。行支架术的3例患者，2例为吻合口狭窄患者表现为支架术后桥血管舒张期流速降低，其中1例阻力增高；1例胸廓内动脉桥闭塞无改变。3例患者左前降支远段舒张期流速增高。结论常规超声结合冠状动脉血流显像技术是可行、可信、无创性探测桥血管通畅性的方法，可用于冠状动脉搭桥术后的随访。     

64层螺旋CT在评价冠状动脉桥血管中的价值

目的探讨64层螺旋CT在诊断冠状动脉桥血管的临床价值。方法对21例冠状动脉搭桥术的患者行64层螺旋CT心、胸部血管造影检查。对所有扫描原始数据行冠状、矢状MPR、曲面重建(CPR)以及VR、MIP重建。由两位有经验的放射科医生对所有图像进行观察,对桥血管狭窄进行诊断,并评价其狭窄程度。8例CT诊断桥血管重度狭窄(管腔狭窄>75%)或闭塞的患者同时行选择性血管造影检查。结果21例患者均可清晰地显示冠状动脉各主要分支,并能清晰地显示其斑块和管腔的狭窄。21例患者经螺旋CT心、胸部血管造影检查,可清晰显示52条桥血管,其中13条桥血管出现再狭窄(10条为大隐静脉桥血管,3条为乳内动脉桥血管),狭窄部位均位于桥血管吻合口处;重度狭窄7条,闭塞1条,此8条桥血管均与选择性血管的结果相吻合,CT评价冠状动脉桥血管重度狭窄的准确性为100%。结论64层螺旋CT心、胸血管造影检查不但能显示冠状动脉桥血管,而且能清晰地显示原始的冠状动脉及冠状动脉与桥血管的吻合口,是评价冠状动脉桥血管的一种有效的可靠的检查方法。     

Endothelin-1 and vein graft occlusion in patients undergoing bypass surgery

The saphenous vein is the most commonly used graft for revascularization procedures in patients with coronary artery disease and critical limb ischaemia. However, the patency rate of this vessel is poor, with a high proportion of patients requiring further surgery. Early graft occlusion is caused by vasoconstriction or thrombus formation, with later stages of graft failure being due to neointimal formation or atherosclerosis. Apart from its potent constrictor action, endothelin-1 is also a potent proliferative and proinflammatory peptide that is implicated in a number of vascular diseases. The surgical trauma caused during preparation of the saphenous vein as a bypass graft stimulates the release of a number of factors affecting vascular reactivity and structure, including endothelin-1. Endothelin-1 not only constricts animal and human isolated saphenous vein segments but also causes vascular smooth muscle proliferation and neointimal thickening in vitro , actions that are mediated via endothelin (A and B) receptors. Experimentally, the effects of subtype-selective and dual receptor antagonists have been shown to inhibit endothelin-1-mediated constriction and cell proliferation of the saphenous vein. In this review, data supporting a role of endothelin-1 in vein graft occlusion are presented, and the therapeutic potential of endothelin receptor antagonists in improving graft performance is discussed.     

Non-selective intra-arterial digital subtraction angiography for the assessment of coronary artery bypass grafts

Non-selective intra-arterial digital subtraction angiography (DSA) was performed immediately before selective coronary and bypass angiography in 33 consecutive symptomatic patients 48± 30 months after coronary surgery, for the assessment of 75 coronary bypass grafts. Forty ml of non-ionic, low-iodine content contrast medium (iohexol) were injected into the ascending aorta at 10–20 ml/sec through a 7 or 8 F femoral pigtail catheter. Electrocardiogram-triggered images were acquired on a Siemens Digitron II apparatus in multiple projections in 24 patients and in a single projection in 9 patients. The results of this technique were compared by two independent angiographers with those of selective graft angiography in the same patients. Patency was shown by DSA in 45 of 54 grafts confirmed to be open by selective angiography (sensitivity 83%). Of 21 occluded grafts, stumps were clearly visible at selective angiography in 18 and at DSA in 9 (sensitivity for graft stumns = 50%, p<0.01) Of 54 patent grafts with selective angiogranhy. the distal anastomosis could be visualized by DSA in 28 (52%), but the resolution was comparable to selective angiography in 20 grafts (37%) only. A non-significant difference in the sensitivity of DSA was observed between patent saphenous grafts to the left anterior descending coronary artery versus all other coronary arteries (95 vs 85%, respectively), while only 1 of 5 patent left internal mammary artery grafts to the left anterior descending coronary artery was visualized. In 16 of 50 grafts (32%) visualized in a second projection substantial additional diagnostic information was obtained. In conclusion, non-selective intra-arterial electrocardiogram-triggered DSA can visualize patent saphenous grafts with a high sensitivity and may be a useful screening tool for bypass grafts patency; false negatives, however, and poor visualization of distal anastomoses limit its routine clinical use.