Pulmonary artery compression by a giant aortocoronary vein graft aneurysm

Late failure of saphenous vein aortocoronary bypass grafts is predominantly due to vein graft atherosclerotic disease. Rarely, saphenous vein aortocoronary bypass grafts undergo aneurysmal degeneration. We report a case of a giant true aneurysm of a saphenous vein aortocoronary bypass graft producing right heart failure from main pulmonary artery compression.     

Involvement of dendritic cells in long-term aortocoronary saphenous vein bypass graft failure.

Antigen-presenting dendritic cells are present in atherosclerotic lesions in human arterial intima, but have not been investigated in atherosclerotic and hyperplastic stenotic lesions that affect vein grafts used as arterial conduits. This study was undertaken to examine whether dendritic cells are present in aortocoronary artery saphenous vein bypass grafts affected by high-grade atheromatous stenosis. Stenotic saphenous vein coronary artery bypass grafts (angiographic luminal stenosis > 75%) were harvested from 10 patients (nine male, one female), aged 4271 years (mean 56.5) at re-do operation. The mean time interval from bypass surgery to the excision of stenotic grafts was 11.5 years (range 2-21). The specimens were fixed in 10% buffered formalin, embedded in paraffin blocks and the sections stained with antibodies to S-100 (to identify dendritic cells), CD3 (T cells), CD68 (macrophages), von Willebrand factor (endothelial cells) and alpha-smooth muscle actin (smooth muscle cells) using avidin-biotin complex immunoperoxidase technique. Normal veins were obtained during saphenous vein femoro-popliteal grafting. The stenotic venous grafts showed histological features typical of extensive arterialization, intimal hyperplasia, atherosclerotic plaque-like lesions, calcification and thrombosis. In areas of intimal hyperplasia, S-10O-positive cells were distributed irregularly among smooth muscle cells. S-100-positive dendritic cells were seen most frequently within atherosclerotic plaque-like lesions where they co-localized with CD3+ cells and CD68+ cells. S-100-positive dendritic cells were also seen accumulating within calcific foci. No S-100-positve cells were found in normal, ungrafted saphenous veins. We conclude that dendritic cells are present in aortocoronary saphenous vein bypass grafts affected by high grade stenosis. Dendritic cells are probably involved in immune mechanisms of atherogenesis through their interactions with T cells and macrophages. The accumulation of dendritic cells within calcific foci suggests their contribution to the calcification of stenotic venous grafts.     

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.     

Multiple aortocoronary bypass saphenous vein graft aneurysms in a 77-year-old man

Aneurysms of aortocoronary saphenous vein bypass grafts are a rare complication of coronary artery bypass grafts. The authors report the incidental finding of four aneurysms in two aortocoronary saphenous vein bypass grafts in a 77-year-old man with progressive generalized weakness, left facial drooping, and digitalis toxicity. A brief review of the literature on this rare condition is also provided.     

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.     

CD40 co-stimulatory molecule expression by dendritic cells in primary atherosclerotic lesions in carotid arteries and in stenotic saphenous vein coronary artery grafts.

We have previously identified dendritic cells in the intima of human large arteries and stenotic vein coronary bypass grafts. The mechanisms by which these dendritic cells might regulate immune responses in atherosclerotic lesions and stenotic vein grafts are unknown. The aim of the present study was to investigate whether dendritic cells in carotid plaques and in stenotic aortocoronary vein grafts express an immunoregulatory molecule CD40.Segments of wall from eight carotid arteries and three stenotic aortocoronary saphenous vein grafts were obtained at operation. CD40+ cells were detected in all specimens of both occluded and stenotic grafts and carotid plaques. Although CD40+ cells of various cell types were intermingled in most areas within the plaques and stenotic grafts, there were sites where CD40+ cells were located in small groups. Consecutive sections demonstrated that a small population of CD40+ cells stained positively for S100. These CD40+/S100+ cells were clustered within the intima but were also found in the media and adventitia. This suggests that dendritic cells, which accumulate within vessels affected by atherosclerosis and graft disease, express CD40 co-stimulatory molecule. The expression of CD40 molecule on the dendritic cells may be important in regulating T cell responses within atherosclerotic plaques and stenotic vein grafts.     

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.     

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.     

The Structural Study of the Saphenous Vein

From November, 1971, to September, 1974, 1,179 patients received aortocoronary saphenous vein bypass grafts at the Cleveland Clinic Hospital. Segments of saphenous vein from each patient were sent for microscopical analysis. These vein segments were classified as normal or abnormal (phlebosclerotic). Four hundred ninety-six normal vein grafts in 295 patients were restudied and had a patency of 87.9%. One hundred forty-four abnormal vein grafts in 86 patients were restudied and showed 89.5% patency.This study suggests that histopathological identification of an abnormal (phlebosclerotic) vein segment does not constitute a determining factor as far as late patency is concerned in a vein segment that is not grossly sclerotic.     

Postoperative percutaneous coronary angioplasty for stenosed aortocoronary vein bypass

This paper was presented to demonstrate the efficacy of postoperative PTCA for varying degree of stenosis aortocoronary bypass with saphenous vein grafts. The following conclusions were drown. 1. The success rate of postoperative PTCA for 15 grafts showed 88.8%. 2. The rate of success for PTCA was much more effective in patients within one year after bypass operations. The authors concluded that postoperative PTCA can be done with excellent rate of success. Therefore, postoperative cine-coronary angiography should be done to evaluate the state of the graft and to decide to perform possible postoperative PTCA in order to keep long time patency rate of saphenous vein grafts.     

Histological survey of the saphenous vein before its use as autologous aortocoronary bypass graft.

A histological examination has been carried out on the saphenous veins used in 150 consecutive patients undergoing aortocoronary bypass. Morphological changes were observed frequently and consisted mainly of fibrosis of the intima and of the medial longitudinal muscular layer. Intimal fibrosis was rarely severe enough to narrow the lumen significantly. Statistical analysis disclosed that the fibrosis of the intima and the medial longitudinal muscular layer do not increase with age. The use of frozen histological sections of the saphenous vein in patients undergoing aortocoronary bypass operations could be considered in order to discard unsuitable grafts and to direct the surgeon to alternative conduits.     

Intimal Hyperplasia: A Cause of Radial Artery Aortocoronary Bypass Graft Failure

Autogenous radial artery grafts have been advocated for those situations in which adequate saphenous vein is not available for aortocoronary bypass procedures. It was anticipated that autogenous artery would demonstrate less predilection to develop the intimal proliferative changes seen with vein grafts in the arterial system. Early clinical experience with 79 patients receiving one or more radial artery grafts has shown that the radial artery is not spared occlusive intimal proliferative changes. Although early restudy of 6 patients was encouraging, late restudy in 29 patients showed 22 of 34 radial artery grafts (64.7%) to be unsatisfactory. Recovered grafts from 3 patients who required a second operation revealed severe generalized intimal hyperplasia. On the basis of this experience we no longer consider the radial artery an alternative conduit for aortocoronary bypass.     

Direct coronary artery surgery for coronary artery occlusive disease

Surgical revascularization of the myocardium for coronary artery occlusive disease has gained great impetus over the past five years with the advent of successful methods of direct surgical reconstruction of the coronary arteries. Seventy-five patients underwent direct coronary artery surgery for ischemic heart disease over the past two and a half years. The indication for coronary arterial revascularization was angina in forty-eight patients, congestive heart failure in twenty-four patients, and recurrent myocardial infarction in three patients. In this group of seventy-five patients there were 105 aortocoronary saphenous vein bypass grafts, five internal mammary-coronary artery bypass grafts, and thirty-five distal endarterectomies combined with aortocoronary vein bypass grafts. Direct coronary artery surgery was combined with resection of a left ventricular aneurysm in seven patients and with aortic valve replacement in three. A single coronary artery was reconstructed in twenty-seven cases and two of the three major coronary arteries were reconstructed in thirty-nine cases.     

Twenty-year follow-up of saphenous vein aortocoronary artery bypass grafting.

The clinical records of our first 100 patients to undergo saphenous vein aortocoronary bypass grafting were reviewed. The procedures were performed between March 19, 1970, and March 30, 1972. The patient population included 84 men, and the mean age was 51.4 years. There were 12 patients with single-vessel disease, 36 with double-vessel disease, and 52 with triple-vessel disease, for an average of 2.4 involved vessels per patient. Forty-eight patients were judged to have diffuse atherosclerotic disease. Twelve patients had left main coronary artery stenoses. Each patient received an average of 1.8 saphenous vein grafts. Thirty-six patients underwent repeat coronary artery bypass grafting after an average of 132.8 months and received an average of 3.5 grafts. This resulted in cumulative reoperative rates of 5%, 14%, 27%, and 36% at 5, 10, 15, and 20 years, respectively. The 5-, 10-, 15-, and 20-year survival rates were 89.8%, 68.4%, 53.1%, and 40.8%, respectively. Survival was not significantly related to the cause of death, cardiac-related causes being predominant. There were no significant relationships between the length of survival and sex, the number of grafts received, or the presence of left main stenosis. Survival was inversely related to age at initial operation (p = 0.046) as well as initial left ventricular end-diastolic pressure (p = 0.033). Survival positively correlated with the occurrence of triple-vessel disease (p = 0.031) and the presence of diffuse disease (p = 0.0077).(ABSTRACT TRUNCATED AT 250 WORDS)     

Giant aneurysm of saphenous vein graft to coronary artery compressing the right atrium.

Aneurysm of reverse aortocoronary saphenous vein graft is a known complication of coronary artery bypass grafting. In this report we present a case of a 60-year-old man who presented 12 years after coronary artery bypass grafting with a giant graft aneurysm of the reverse aortocoronary saphenous vein graft to the right coronary artery, compressing the right atrium. Spiral computed tomography was used to identify the aneurysm measuring 7 x 6 x 7 cm. We also reviewed the English-language literature and found reports of 50 patients with similar aneurysms of which 30 (61%) were identified as true aneurysms and 17 (33%) were identified as pseudoaneurysms. Three patients could not be identified into either group. We reviewed the presenting symptoms, diagnostic tools, and treatment options for this rare entity. An understanding of the pathophysiology of reverse aortocoronary saphenous vein graft aneurysm is important to prevent the possibility of aneurysm rupture, embolization, myocardial infarction, or death.     

Aneurysm of aortocoronary saphenous vein graft: case report and literature review

True aneurysms of aortocoronary saphenous vein bypass grafts are a relatively rare complication of bypass surgery, but because the complications of thrombosis, embolization, or rupture are potentially fatal, this condition requires immediate surgical intervention. We describe a 78-year-old man who had undergone coronary bypass 15 years previously and who presented with a saphenous vein graft that was severely degenerated and aneurysmally enlarged throughout its course, measuring as much as 5 to 6 cm in certain locations. Redo coronary artery bypass grafting using the right and left internal thoracic arteries and resection of the aneurysm were performed. We also present a review of the literature regarding diagnosis, management, and treatment of this condition.     

Aneurysm of the main stem of the left coronary artery associated with aortic insufficiency and aneurysm of the ascending aorta. Report of a case with successful surgical repair.

A case of aneurysm of the main stem of the left coronary artery associated with aortic insufficiency and an aneurysm of the ascending aorta is reported. The importance of coronary angiography in diagnosing this condition is illustrated. Surgical repair included isolation of the coronary aneurysm and replacement of the ascending aorta and aortic valve, combined with triple aortocoronary saphenous vein bypass grafts. A review of the aetiology, clinical features, and surgical management of coronary artery aneurysms is presented.     

Mediastinal wound infection and aortocoronary graft patency.

In our experience, eight of ten aortocoronary grafts in five patients remained patent in the face of mediastinal infection. Combining reports of seventeen other grafts from the literature, we conclude that patency can be anticipated in approximately 70 per cent of such grafts and that mediastinal infection does not necessarily adversely affect aortocoronary saphenous vein bypass graft patency. We recommend aggressive therapy of mediastinal infection in this setting due to the high survival rate which can be anticipated with modern methods of therapy, as well as the high probability of graft patency.