Percutaneous management of a saphenous vein graft perforation using a covered stent and final coil embolization technique

Coronary artery perforation as a result of percutaneous coronary intervention is a rare complication which may result in cardiac tamponade, myocardial infarction and death. Perforation of a saphenous vein graft is unusual and generally requires surgical intervention. We describe a novel percutaneous approach that facilitated the successful management of a potentially catastrophic saphenous vein graft (SVG) perforation.     

On the biology of saphenous vein grafts fitted with external synthetic sheaths and stents

Autologous saphenous vein is used as a conduit to bypass atherosclerotic lesions in both the coronary artery (coronary artery bypass graft surgery [CABG]) and in femoral arteries (infrainguinal bypass graft surgery [IIBS]). Despite the undoubted success and benefits of the procedures, graft failure occurs in 50% of cases within 10 years after surgery. A principal cause of late vein graft failure is intimal and medial hyperplasia and superimposed atherogenesis. Apart from lipid lowering therapy, no intervention has hitherto proved clinically effective in preventing late vein graft failure which clearly constitutes a major clinical and economic problem that needs to be urgently resolved. However, we have studied the effect of external synthetic stents and sheaths in pig models of vein into artery interposition grafting and found them to have a profound effect on vein graft remodelling and thickening. In this review, therefore, we will summarise the mechanisms underlying vein graft failure and how these stents influence these processes and the possible mechanisms involved as well as the application of these devices in preventing vein graft failure clinically.     

Structural features of cell death in atherosclerotic lesions affecting long-term aortocoronary saphenous vein bypass grafts

Aortocoronary saphenous vein bypass grafts fail because of structural pathologies (thrombosis, intimal hyperplasia and atherosclerosis) within the 'arterialized' vein leading to graft stenosis. This study examined structural characteristics of atherosclerotic alterations in long-term aortocoronary artery saphenous vein bypass grafts with particular attention to the features of cell death in atherosclerotic lesions. Stenotic vein grafts were obtained from 10 patients at redo coronary artery bypass grafting operations. All the grafts were affected by histological abnormalities, with eight out of ten grafts showing evidence of atherosclerotic alterations in the intimal hyperplastic layer. Areas containing foam cells were examined by electron microscopy. Cells with cytoplasmic lipid accumulations were characterized by varying degrees of chromatin condensation, fragmentation or dispersion, by focal areas of oedema and vacuolisation of their cytoplasm, and by plasmalemmal destruction. Some lipid-filled cells exhibiting signs of destruction contained myofilaments and basal membrane fragments, allowing them to be identified as smooth muscle cells. Macrophage foam cells were found to have undergone similar destruction. No cells showing nuclear degeneration were observed to have intact cytoplasmic organelles. Neither were apoptotic bodies identified, but necrotic remnants were frequently seen. The results suggest that cell death in atherosclerotic lesions affecting aortocoronary artery saphenous vein bypass grafts occurs through oncosis rather than by apoptosis.     

Histological appearances of the long saphenous vein

The long saphenous vein is frequently used as a graft in both coronary artery and femoro-distal bypass surgery. The histological changes which are seen after implantation into the arterial system have been well documented in the past, but little attention has been focused on the histological appearances of the donor long saphenous vein prior to grafting. In this study, samples of the long saphenous vein in excess of that required for bypass have been examined. In none of the veins did the histological appearances conform to the described normal. All showed evidence of intimal fibrosis which contained elastic tissue and enmeshed smooth muscle cells. The longitudinal and circular muscle layers showed evidence of muscle cell hypertrophy with increase in intervening connective tissue. Elsewhere, similar histological changes have been attributed to 'arterialization'. This study shows that many of the changes are present prior to grafting and may be important in graft failure.     

Thromboangiitis obliterans (Buerger's disease) in a saphenous vein arterial graft

Thromboangiitis obliterans (Buerger's disease) is an uncommon variety of occlusive peripheral vascular disease, occurring predominantly in young male tobacco smokers. The vascular lesion in the acute stage of thromboangiitis obliterans is distinctive and affects both the arteries and veins. Described here is an unusual case of thromboangiitis obliterans occurring in a saphenous vein used for coronary artery bypass graft in a middle-aged man who, against advice, had continued to smoke after the myocardial revascularization surgery. To the author's knowledge, thromboangiitis obliterans in arterial vein graft has not been reported previously.     

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。     

A novel promising therapy for vein graft restenosis: overexpressed Nogo-B induces vascular smooth muscle cell apoptosis by activation of the JNK/p38 MAPK signaling pathway

Coronary artery bypass grafting using autologous saphenous veins is a standard surgical therapy for coronary artery diseases. However, post-procedure vein graft restenosis impedes its effectiveness and often leads to a high morbidity and mortality, and a reduction in the quality of life. Neointimal hyperplasia is a major cause of vein graft occlusion, and is characterized by an imbalance between vascular smooth muscle cell (VSMC) proliferation and apoptosis. So far, there have been no optimally effective pharmacological or non-pharmacological interventions for the prevention and treatment of vein graft occlusion. Gene therapy has emerged as a potential therapeutic approach, as bypass grafts can be genetically modified ex vivo prior to grafting in the coronary vasculature. Nogo-B, recognized as a vascular protective factor, has been shown to reduce neointimal thickening in graft veins, but its specific mechanism is uncertain. Evidence from diverse sources has documented that overexpressed Nogo-B can induce apoptosis of variant cancer cell lines, suggesting that overexpressed Nogo-B may have a pro-apoptotic role in VSMC. Furthermore, we have found that Nogo-B is associated with the mitogen-activated protein kinase (MAPK) signaling pathway, which plays important roles in cell growth, differentiation, and apoptosis. Recent studies have shown that VSMC apoptosis can be induced by activation of the c-Jun-N-terminal kinase (JNK)/p38 MAPK pathway. Therefore, we propose that overproduction of Nogo-B in the graft vein could result in reduced neointimal hyperplasia, the mechanism of which involves increased VSMC apoptosis induced by activation of the JNK/p38 MAPK pathway. This study will provide a new clue for gene therapy in the treatment of vein graft failure.     

Coronary artery bypass grafting for Fabry's disease: veins more suitable than arteries?

Coronary artery bypass grafting was performed in a 54-year-old man affected by untreated Fabry's disease. Left internal mammary artery (LIMA) and saphenous vein grafts were implanted. Surgical samples of LIMA revealed diffuse glycosphyngolipid infiltration of smooth muscle cells, whereas SV was normal. After surgery, the patient received antithrombotic and enzyme replacement therapy. At 1-year follow-up, LIMA graft occluded, whereas saphenous vein graft remained patent. In Fabry's disease, veins, probably because of a low pressure load, seem to be spared from glycosphingolipid accumulation and are more suitable than arteries for grafting. A preventive histology of conduits is suggested before graft selection.     

Electron-microscopic detection of apoptotic and necrotic cell death in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts

Aortocoronary saphenous vein bypass grafts undergo structural alterations within the arterialized vein, resulting in graft stenosis and failure. Areas of the acellular intima contribute to fissuring, cracking and ulceration, while areas of the media become highly vascular but thinned. This study aimed to examine the ultrastructural features of cell death, including apoptosis and necrosis, in non-atherosclerotic areas of the stenotic aortocoronary saphenous vein bypass grafts. Thirteen stenotic vein grafts were obtained at redo coronary artery bypass grafting. The ultrastructural features of cell death were analysed by electron microscopy. Typical features of necrosis, including focal areas of cytoplasmic oedema, plasmalemmal destruction and nuclear condensation with cytoplasmic organelle destruction, were observed throughout the intima and media. Features of apoptosis, including the presence of apoptotic bodies, were also identified in the hyperplastic intima and its adjacent media. Our observations suggest that both apoptosis and necrosis occur in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts.     

Observations on detailed histology of the internal thoracic artery and their relevance to its comparatively low incidence of atheroma

The internal thoracic artery (ita) is of value as a coronary artery bypass graft. It is much less prone to develop atheroma than coronary arteries and much less prone to develop graft occlusive disease than the alternative saphenous vein graft, but the reasons for its comparative resistance to atheroma are unclear. We have sought to define the detailed structure of the artery along its length and have shown that the media of the artery changes from an elastic structure in its proximal part to a muscular one in its distal part. The internal elastic lamina has a well-defined structure at all levels, in contrast to the external elastic lamina which becomes well defined only in its distal part. The significant difference in the structure of the media of the ita, compared to that described for the coronary arteries, may be relevant to the observed difference in atheroma between this artery and the similarly sized epicardial coronary arteries. © 1994 Wiley-Liss, Inc.     

Full Mimicking of Coronary Hemodynamics for Ex-Vivo Stimulation of Human Saphenous Veins

After coronary artery bypass grafting, structural modifications of the saphenous vein wall lead to lumen narrowing in response to the altered hemodynamic conditions. Here we present the design of a novel ex vivo culture system conceived for mimicking central coronary artery hemodynamics, and we report the results of biomechanical stimulation experiments using human saphenous vein samples. The novel pulsatile system used an aortic-like pressure for forcing a time-dependent coronary-like resistance to obtain the corresponding coronary-like flow rate. The obtained pulsatile pressures and flow rates (diastolic/systolic: 80/120 mmHg and 200/100 mL/min, respectively) showed a reliable mimicking of the complex coronary hemodynamic environment. Saphenous vein segments from patients undergoing coronary artery bypass grafting (n = 12) were subjected to stimulation in our bioreactor with coronary pulsatile pressure/flow patterns or with venous-like perfusion. After 7-day stimulation, SVs were fixed and stained for morphometric evaluation and immunofluorescence. Results were compared with untreated segments of the same veins. Morphometric and immunofluorescence analysis revealed that 7 days of pulsatile stimulation: (i) did not affect integrity of the vessel wall and lumen perimeter, (ii) significantly decreased both intima and media thickness, (iii) led to partial endothelial denudation, and (iv) induced apoptosis in the vessel wall. These data are consistent with the early vessel remodeling events involved in venous bypass adaptation to arterial flow/pressure patterns. The pulsatile system proved to be a suitable device to identify ex vivo mechanical cues leading to graft adaptation.     

Effect of angioplasty and grafting on porcine vascular nerves: a potential neurotropic role for endothelin-1

The most commonly performed procedure for treating coronary artery stenosis is percutaneous transluminal coronary angioplasty (PTCA) and, where the vessel lumen is severely narrowed, coronary artery bypass grafting (CABG). In PTCA, regions of atherosclerotic plaques are disrupted, and the vessel lumen increased by inflating a balloon catheter. In CABG an autologous saphenous vein into coronary artery interposition graft is performed in order to bypass occluded regions of epicardial coronary arteries. Both interventions cause varying degrees of vascular damage and the long-term efficacy of these procedures is limited by a high incidence of neointimal formation and subsequent vascular restenosis (Bach et al. 1994; Bryan & Angelini, 1994).
The endothelium-derived constrictor peptide, endothelin-1 (ET-1) (Yanagisawa et al. 1988), also possesses mitogenic activity on vascular smooth muscle cells (Hirata et al. 1989) and has been suggested as playing a role in atherosclerosis (Dashwood et al. 1993; Zeiher et al. 1994) and intimal hyperplasia (Dashwood et al. 1993; Douglas et al. 1994).     

Estimation of wall shear stress in bypass grafts with computational fluid dynamics method

Coronary artery bypass graft (CABG) operation for coronary artery disease with different types of grafts has a large clinical application world wide. Immediately after this operation patients are usually relieved of their chest pain and have improved cardiac function. However, after a while, these bypass grafts may fail due to for example, neointimal hyperplasia or thrombosis. One of the causes for this bypass graft failure is assumed to be the blood flow with low wall shear stress. The aim of this research is to estimate the wall shear stress in a graft and thus to locate areas were wall shear stress is low. This was done with the help of a blood flow computer model. Post-operative biplane angiograms of the graft were recorded, and from these the three-dimensional geometry of the graft was reconstructed and imported into the computational fluid dynamics (CFD) program FLUENT. The stationary diastolic flow through the grafts was calculated, and the wall shear stress distribution was estimated. This procedure was carried out for one native vessel and two different types of bypass grafts. One bypass graft was a saphenous vein and the other one was a varicose saphenous vein encased in a fine, flexible metal mesh. The mesh was attached to give the graft a defined diameter. The computational results show that each graft has distinct areas of low wall shear stress. The graft with the metal mesh has an area of low wall shear stress (< 1 Pa, stationary flow), which is four times smaller than the respective areas in the other graft and in the native vessel. This is thought to be caused by the smaller and more uniform diameter of the metal mesh-reinforced graft.     

Early clinical results of St. Jude Medical Symmetry aortic connector

An automated anastomosis device named St. Jude Medical symmetry aortic connector has been used worldwide for off-pump coronary artery bypass grafting. However, early graft obstruction was recently reported, and its predictors should be clarified. From April 2002 to March 2004, 38 patients in our institution underwent off-pump coronary artery bypass grafting using the St. Jude Medical Symmetry aortic connector for saphenous vein graft (SVG) procedures; measurement of intraoperative graft flow and postoperative coronary angiography was performed. Early SVG events occurred in 9 (24%) patients: 8 occlusion cases and 1 case of stenosis. Predictors of early SVG events were assessed from a comparative study. Univariate logistic regression identified hyperlipidemia as the only significant predictor of early SVG events (P = 0.02, odds ratio 7.78). Lower SVG flow rate and poor ejection fraction did not show statistical significance (P = 0.09, odds ratio 1.09 and P = 0.09, odds ratio 0.96). The SVG event rate was much higher for the left circumflex branch compared with other locations (31% vs. 9%, P = 0.03) and decreased with increasing aortic connector size (small, 32%; median, 14%; large, 0%). Multivariate analysis did not identify a predictor of SVG events. The aortic connector is associated with a high incidence of early SVG events. Patients should be cautiously selected and the procedure should not be used for left anterior descending coronary artery or culprit lesions.     

The heart in Tangier disease. Severe coronary atherosclerosis with near absence of high-density lipoprotein cholesterol.

Cardiac necropsy findings are described in a 72-year-old man with Tangier disease whose plasma total cholesterol levels averaged 70 mg/dL, low-density lipoprotein cholesterol level was 45 mg/dL, and high-density lipoprotein cholesterol level was 1.4 mg/dL, and who had coronary artery bypass grafting for severe atherosclerotic coronary artery disease. At necropsy, 24 of the 72 (33%) 5-mm segments of the 4 major (right, left main, left anterior descending, and left circumflex) native coronary arteries and 4 of the 27 (15%) 5-mm segments of the saphenous vein aortocoronary bypass conduits were narrowed by more than 75% in cross-sectional area by atherosclerotic plaques. The plaques were composed primarily (91% to 97%) of fibrous tissue. Oil red O staining, polarized light microscopy, and electron microscopy revealed cholesterol deposits in the plaques and in the walls of coronary arteries, saphenous vein grafts, and aorta. Such deposits also were found in foam cells of histiocytic origin, fibroblasts in all four cardiac valves, and in Schwann cells of cardiac nerves.     

Uterine artery as an arterial conduit for coronary artery bypass graft (CABG) surgery in women: A role for estrogen-receptor alpha (ER-α) in the prevention of post-CABG accelerated atherosclerosis and graft disease

Coronary artery bypass graft (CABG) surgery is the standard of care in the treatment of advanced coronary artery disease (CAD). In order to bypass coronary occlusions, CABG surgery traditionally employs grafts from the left internal thoracic/mammary artery (LITA/IMA), radial artery (RA), and greater saphenous vein (SV). The risk of CABG failure is reported to be higher, or at best similar, for women than for men, and it relates primarily to post-operative accelerated atherosclerosis leading to graft stenosis and recurrent angina, a phenomenon known as “coronary artery bypass graft disease”. In this paper, the authors hypothesize that employing an alternative arterial conduit may help reduce the rate of post-CABG accelerated atherosclerosis in women, and propose that a uterine artery specimen be used instead. Given its greater density of estrogen-receptor alpha (ER-α) relative to other mammalian endothelial cells in the vasculature, uterine arteries may exhibit important anti-atherosclerotic properties. Theoretically, this effect may be amplified with the adjuvant administration of low-dose selective ER-α agonist modulator (SERM) therapy.     

Subclavian artery stenosis as a cause of acute coronary syndrome in a patient after coronary artery bypass grafting

We described a case of a 74-year-old man who suffered from acute coronary syndrome 7 years after coronary artery bypass grafting. The patient underwent angioplasty of the obtuse marginal branch of the left coronary artery from venous graft access, which did not result in relief of ailments. Only angioplasty of the narrowed subclavian artery caused an improvement in the patient''s condition. The clinical significance of narrowing within the subclavian artery in patients after the procedure of implanting the left subclavian artery into the coronary artery system was discussed.     

Left main trunk ostial stenosis and aortic incompetence in Takayasu's arteritis.

A 41-year-old woman with recent onset of heart failure and angina due to aortic valve incompetence and critical left coronary ostium stenosis in the setting of Takayasu's arteritis is reported. The patient was successfully surgically treated by aortic valve replacement and coronary artery bypass with saphenous vein graft, showing a cardiac event-free 17 months follow-up. Takayasu's arteritis must be included among the possible causes of coronary artery disease and aortic valve incompetence in young female patients. Although chronic inflammation of the aortic wall may result in late graft occlusion, surgical therapy is effective for short and mid-term clinical improvement.     

Heterotopic thyroid tissue in the heart

Heterotopic thyroid tissue, presumably due to an embryological developmental abnormality, was discovered incidentally within the right atrial wall of an elderly woman who underwent coronary arterial aortic saphenous vein bypass grafting. As far as we are aware, this is only the third patient with thyroid heterotopia of the heart to be documented.     

冠状动脉旁路移植治疗冠状动脉肌桥9例分析

目的回顾冠状动脉旁路移植术治疗症状性肌桥的外科治疗经验及结果。方法选取2004年3月至2011年1月因冠状动脉肌桥导致冠状幼脉血流堵塞需行冠状动脉旁路移植术的患者资料9例,采用胸廊内动脉到前降支进行旁路移植,2例取大隐静脉与其他病变冠状动脉进行旁路移植。结果全组无患者死亡,无术中相关并发症发生。所有患者随访4个月至7年,临床症状均明显改善,无心绞痛发生,无心肌梗死及其他主要心血管不良事件（再血管化或死亡等）发生。结论冠状动脉旁路移植治疗有症状的肌桥安全、有效。