Amyloidosis in saphenous vein aortocoronary bypass grafts

A patient in whom idiopathic amyloidosis of aortocoronary saphenous vein grafts was found at autopsy two years after myocardial revascularization due to coronary atherosclerosis is reported. Idiopathic generalized immunocyte derived amyloidosis extensively studied at autopsy was obviously present at the time of surgery although it remained unnoticed macroscopically in the inserted graft. It appears that simultaneously with arterialization further deposition and also significant redistribution of amyloid within the walls of the vein grafts additionally took place after their insertion. It seems interesting that in spite of the amyloidosis the grafts functioned well and were found patent two years after surgery.     

Intraluminal shunting of operatively severed aortocoronary saphenous vein grafts

Restoration of myocardial perfusion using plastic shunts in severed aortocoronary bypass grafts is described.     

Sutureless fixation of long aortocoronary saphenous vein grafts with oxidized regenerated cellulose

A technique of sutureless epicardial fixation of long aortocoronary saphenous vein grafts using oxidized regenerated cellulose is illustrated. Sutureless fixation has been previously performed with fibrin glue. Possible advantages of using oxidized regenerated cellulose instead of fibrin glue are discussed.     

Expression of vascular endothelial growth factor in aortocoronary saphenous vein bypass grafts

Neovascularisation is a prominent feature of long-term aortocoronary saphenous vein bypass grafts but mechanisms involved in the formation of neovessels have not been previously studied. Vascular Endothelial Growth Factor (VEGF) is an important angiogenic factor that induces migration and proliferation of endothelial cells, enhances permeability and modulates thrombogenecity. This study investigated the expression of VEGF in aortocoronary saphenous vein bypass grafts. Aortocoronary saphenous vein bypass grafts with angiographic luminal stenosis of >75% were explanted from 14 patients at redo coronary artery bypass grafting. The grafts demonstrated two distinct forms of graft occlusion: four out of the 14 graft occlusions (29%) resulted from severe hyperplastic transformation of the intima complicated by thrombi attached to the degenerating liminal endothelium; the remaining graft occlusions (71%) were due to the development of atherosclerotic lesions associated with mural thrombosis. Hiperplastically altered intimal segments were practically free of neovascularisation while atherosclerotic-like lesions contained neovessels irregularly distributed throughout. Intimal neovessels were located exclusively in microzones enriched with VEGF-expressing cells and, furthermore, neovascular endothelial cells themselves also displayed VEGF immunopositivity. Double-immunostaining revealed that in areas of neovascularisation, the vast majority macrophages (CD68+) expressed VEGF. Some CD68+ foam cells that surrounded branches of neovascularisation were also VEGF-positive. These findings suggest that VEGF expressed by neovascular endothelial cells and by macrophages may act as a local regulator of endothelial cells functions and may induce intimal neovascularisation in aortocoronary saphenous vein bypass grafts affected by atherosclerosis.     

Modulation of phosphatidylinositol 3-kinase signaling reduces intimal hyperplasia in aortocoronary saphenous vein grafts

OBJECTIVES: Fifty percent of human aortocoronary saphenous vein grafts are occluded after 10 years. Intimal hyperplasia is an initial step in graft occlusion and consists of vascular smooth muscle cell proliferation. Phosphatidylinositol 3-kinase and its downstream regulator, the inositol 3-phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10), are important regulators of vascular smooth muscle cell proliferation, migration, and cell death. This study tests whether overexpression of PTEN in aortocoronary saphenous vein grafts can reduce intimal hyperplasia. METHODS: Adult dogs underwent aortocoronary bypass grafting to the left anterior descending artery by using the autologous saphenous vein. Saphenous vein grafts were treated with phosphate-buffered saline (n = 9), empty adenovirus (n = 8), or adenovirus encoding for PTEN (n = 8). Arteriography at 30 and 90 days assessed saphenous vein graft patency. A subset received saphenous vein grafts treated with a marker transgene (beta-galactosidase, n = 3), empty adenovirus (n = 4), or adenovirus encoding for PTEN (n = 4) and were killed on postoperative day 3 to confirm expression. Vascular smooth muscle cells were isolated from canine saphenous vein infected with adenovirus encoding for PTEN, and immunoblotting and proliferation assays were performed. RESULTS: Saphenous vein graft transgene expression was confirmed by means of immunohistochemistry, immunoblotting, and polymerase chain reaction. Arteriograms revealed all saphenous vein grafts to be patent. Saphenous vein grafts treated with adenovirus encoding for PTEN demonstrated reduced intimal area compared with those treated with empty adenovirus and phosphate-buffered saline (1.39 +/- 0.11 vs 2.35 +/- 0.3 and 2.57 +/- 0.4 mm 2 , P < .05), and the intima/media ratio was lower in saphenous vein grafts treated with adenovirus encoding for PTEN (0.50 +/- 0.05 vs 1.43 +/- 0.18 and 1.11 +/- 0.14, P < .005). PTEN overexpression in vascular smooth muscle cells inhibited platelet-derived growth factor-induced phosphorylation of Akt, a downstream effector of phosphatidylinositol 3-kinase. PTEN-treated vascular smooth muscle cells demonstrated decreased basal, platelet-derived growth factor-stimulated, and serum-stimulated proliferation. CONCLUSION: This study demonstrates that PTEN overexpression in aortocoronary saphenous vein grafts reduces intimal hyperplasia. The mechanism of this antiproliferative effect in vascular smooth muscle cells is likely due to inhibition of phosphatidylinositol 3-kinase signaling through Akt, with resultant decreases in vascular smooth muscle cell growth and survival. Therefore modulation of the phosphatidylinositol 3-kinase pathway through PTEN overexpression might represent a novel therapy to prevent saphenous vein graft intimal hyperplasia after coronary artery bypass grafting.     

Results of reoperation for failed aortocoronary bypass grafts.

Thirty-one patients underwent reoperation for failure of one or more previous aortocoronary bypass grafts. Thirty-nine grafts were replaced. Twenty-four grafts were constructed to vessels not thought to be significantly diseased at initial operation. There were no early or late deaths. Postoperative morbidity was comparable to initial prodecures. Of 24 patients followed up for more than six months., 62% clearly experienced improvement without evidence of perioperative or postoperative infarction. Reoperation for failed aortocoronary bypass grafts can be achieved without excess risk, but with long-term results less optimistic than initial procedures.     

Immunohistochemical and ultrastructural evidence that dendritic cells infiltrate stenotic aortocoronary saphenous vein bypass grafts

We earlier speculated that antigen-presenting dendritic cells may be involved in the immune reactions leading to saphenous vein bypass graft failure. The purpose of this study was to confirm whether dendritic cells are present in stenotic human saphenous vein bypass grafts. Segments of stenotic saphenous vein grafts were explanted from 14 patients at re-do bypass operation and ten normal saphenous veins were harvested during femoro-popliteal grafting. Sections of specimens were analysed using cell type specific antibodies to identify dendritic cells (CD1a, S-100), T-lymphocytes (CD3), macrophages (CD68), smooth muscle cells (alpha-SMA) and endothelial cells (FVIII). Dual immunostaining, confocal immunofluorescent laser scanning microscopy and electron microscopy were used. Stenotic grafts showed structural alterations of intimal hyperplasia and varying degrees of atherosclerotic degeneration. No cells expressing CD1a and S-100 were observed in the intima and media of normal saphenous veins. Cells expressing these antigens were present around areas of medial neovascularization and within intimal atherosclerotic lesions in saphenous vein bypass grafts. Electron microscopy demonstrated the presence of cells containing a well-developed tubulovesicular system which is unique to cells from the dendritic cell family. Double immunohistochemistry and confocal immunofluorescent microscopy revealed the co-localization of T-lymphocytes with dendritic cells. Dendritic cells are present in stenotic saphenous vein bypass grafts. Dendritic cells may be responsible for antigen presentation and modulation of immune reactions in accelerated graft atherosclerosis through their interaction with T-lymphocytes.     

Covered perforated aortocoronary saphenous vein graft aneurysm

Abstract   We report a case of a 75-year-old man suffering from a covered perforated aneurysm of a saphenous bypass graft to the right coronary artery (RCA) constructed 22 years ago. Additional complete revascularization had been performed in 2001. A thoracic computed tomography scan for evaluation of fever of unknown origin had revealed a huge hematoma in front of the right heart. Coronary angiography showed open bypasses but an irregular-shaped aneurysm of the venous graft to the RCA right before the distal anastomosis. Occurrence of a new right-sided pleural effusion led to the emergent operation since rupture of the aneurysm and drainage into the pleura was likely. A massive precordial hematoma was found and the existence of the perforated aneurysm could be confirmed. After institution of cardiopulmonary bypass the graft was resected. Since the patient had a functioning bypass to the RIVP, there was no need for additional revascularization. The patient underwent an uneventful postoperative course.     

Gene delivery to aortocoronary saphenous vein grafts in a large animal model of intimal hyperplasia

OBJECTIVE: More than 50% of aortocoronary saphenous vein grafts are occluded 10 years after surgery. Intimal hyperplasia is an initial, critical step in the progression toward occlusion. To date, no clinically relevant large animal models of aortocoronary saphenous vein graft intimal hyperplasia have been fully characterized. Gene therapy holds promise as a novel treatment for aortocoronary saphenous vein graft intimal hyperplasia. The 2 objectives of this study are to characterize a canine model of aortocoronary saphenous vein graft intimal hyperplasia and to demonstrate that ex vivo gene delivery is possible in these grafts using adenoviral vectors. METHODS: Ten dogs underwent aortocoronary bypass grafting using saphenous veins. Six dogs underwent serial arteriograms to monitor graft patency. On postoperative day 90, the dogs were killed and their grafted and nongrafted saphenous veins were studied histologically. Four dogs underwent the same procedure, but their saphenous veins were treated with 1 x 10(12) total viral particles of a replication-deficient, recombinant adenovirus containing beta-galactosidase (n = 2) or the beta-adrenergic receptor kinase carboxyl terminus (n = 2). These animals were killed on postoperative day 7 for determination of transgene expression. RESULTS: All grafts were demonstrated patent by arteriogram before the animals were killed. The mean intimal area of the saphenous vein grafts was increased when compared with that of the nongrafted saphenous veins (2.83 mm(2) vs 0.09 mm(2), P <.0008). Adenoviral-treated saphenous vein grafts demonstrated positive transgene expression either by X-gal staining (beta-galactosidase) or Northern analysis (beta-adrenergic receptor kinase carboxyl terminus). CONCLUSION: This study characterizes a clinically relevant canine model of aortocoronary saphenous vein graft intimal hyperplasia. In addition, it demonstrates that adenoviral vectors can be delivered ex vivo to the saphenous vein graft vessel wall at subphysiologic distension pressures. This model may be used in future studies to manipulate molecular targets critical in aortocoronary saphenous vein graft intimal hyperplasia.     

Evaluation of aortocoronary bypass operation using a He-Ne laser flowmeter--comparison between internal mammary artery grafts and saphenous vein grafts

It was very difficult to measure myocardial blood flow in clinical cases. Recently, a He-Ne laser doppler flowmeter was developed, and we made it possible to measure the pre-and post-operative myocardial blood flow in cases of coronary artery bypass grafting (CABG). We applied a laser flowmeter to 30 cases of bypass grafting to the left anterior descending coronary artery (18 cases with IMAG and 12 cases with SVG). The preoperative myocardial blood flow at the right ventricular anterior wall was 77 +/- 15 ml/min/100 gr, and the postoperative flow at the same point was 81 +/- 12 ml/min/100 gr. There was no significant change between the pre-operative value and the postoperative one. Myocardial blood flow at the left ventricular anterior wall in SVG group significantly increased from the preoperative value of 58 +/- 11 ml/min/100 gr to the postoperative value of 86 +/- 9 ml/min/100 gr (p less than 0.001). In IMAG group, myocardial blood flow at the left ventricular anterior wall similarly increased from 73 +/- 14 ml/min/100 gr to 83 +/- 15 ml/min/100 gr (p less than 0.01). The postoperative value of IMAG group was almost equal to the value of SVG group. The increased rate of myocardial blood flow at the left ventricular anterior wall was 52 +/- 32% in SVG group and 18 +/- 12% in IMAG group. These rates were obviously distinguished from the increased rate at the right ventricular anterior wall.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of saphenous vein grafts flow by Doppler echocardiography

In an effort to evaluate flow characteristics of the saphenous vein grafts (SVG) after coronary artery bypass grafting, we performed duplex scanning of SVG which were anastomosed to the left anterior descending artery in 12 patients, and compared those indexes with 34 internal thoracic artery grafts (ITAG). The SVG were observed with a 7.5 MHz duplex scanner through the anterior intercostal space. The diameter of the vessel, systolic peak velocity, and diastolic peak velocity were recorded in both groups, and systolic flow volume, diastolic flow volume, and velocity ratio were calculated. The systolic and diastolic peak velocity of SVG were predominantly lower than ITAG. No difference in the diameter and flow ratio could not be demonstrated between 2 groups. The flow volume of SVG were also predominantly lower than that of ITAG throughout cardiac cycle. This study reveals that advanced stenotic change were caused in the SVG group and suggest the occurrence of vein grafts disease long after coronary artery bypass grafting.     

Surgical management: saphenous vein grafts

Peyronie's disease is a medically and surgically challenging condition to manage. Most surgical techniques to correct the penile deformity often shorten the penis and do not address the issue of hourglass deformity when present. We describe our indications, rationale and technique for the use of a saphenous vein graft after a curvature correcting plaque incision. In reviewing multiple series, this approach yields similar results-incidence of residual curvature: 4-20%, decreased potency: 5-20%, penile shortening: 17-40%. While harvesting the vein would require a second incision, the use of autologous vein appears to be associated with the least amount of intracavernosal fibrosis. We propose that saphenous vein is currently the best material available for tunical patching. The technique and results of circular venous grafting for patients with severe penile shortening secondary to Peyronie's disease is also discussed.     

Mycotic aortocoronary saphenous vein graft aneurysm presenting with unstable angina pectoris

We report the case of a 60-year-old man with a history of coronary bypass surgery 20 years prior who had a fever, chest pain, and a mediastinal mass develop after a complicated postoperative course of abdominal aortic aneurysm resection. A mycotic aneurysm of the saphenous vein graft to his left anterior descending coronary artery was diagnosed based on blood culture results and visualization of the aneurysm before resection. A summary of the saphenous vein graft aneurysm and pseudoaneurysm cause, diagnosis, and management is detailed.     

The short saphenous vein: an alternative to the long saphenous vein for aortocoronary bypass.

The long saphenous vein and internal mammary artery are considered at present to be the best grafts available for coronary artery bypass. Patients who have had bilateral long saphenous vein stripping and who require multiple aortocoronary bypass grafts present a challenge to the cardiac surgeon. The short saphenous vein appears to be a suitable alterative.