INTRODUCTION The true aneurysm formation of the autogenous saphenous vein graft (ASVG) is a very rare complication after bypass surgery [1 -5]. In 1969 Pillet [1] first described a true fusiform aneurysm formation of the ASVG which had been used as a replacement of the iwured superficial femoral artery in 26-year-old male patient. We present nine cases. CASE!. A 71-year-old man with previous history of arterial hypertension and higher serum lipid level, was admitted with an asymptomatic pulsating swelling of the medial portion on the thigh. Five years ago the bellow knee F-P bypass with ASVG due to occlusive disease has been performed. The transfemoral angiography (Figure 1) showed patent graft with fusiform true aneurysm formation at its mid portion. This aneurysm has been replaced with PTFE graft. The pathohistological examination showed an atherosclerotic origin of the aneurysm. This patient died four years after operation due to myocardial infarction with patent graft. CASE 2. A 57-year-old female with previous history of arterial hypertension and higher serum lipid level, had an elective resection and replacement of the superficial femoral artery aneurysm. For the reconstruction an ASVG was used. The saphenous vein showed postflebitic changes. Four years later she was admitted with asymptomatic pulsating mass of the mid portion of the thigh. The control transfemoral angiography showed patent graft with fusiform aneurysm formation of its mid portion. After aneurismal resection, an above knee F-P bypass with 8 mm PTFE graft was performed. A pathohistological examination showed a partially degenerated elastic membrane with fragmentation and disruption, without atherosclerosis (Figure 2). During the follow up period an elective resection of the subclavian artery aneurysm as well as abdominal aortic aneurysm, were performed. CASE3. A subclavian artery aneurysm caused by TOS has been repaired with sapehnous vein graft at 40-year-old female patient with regular arterial tension and normal serum lipid level. The pathohistologycal examination showed an intimai fibroelastosis associated with intimai and medial connective tissue proliferation of the aneurysm. The atherosclerotic changes were absent. Four years later this patient has been admitted urgently with ischemia of the left hand, absent distala arterial pulses and with asymptomatic pulsating mass over the supradavicular area. The Duplex ultrasonography and angiography, showed aneurysm of the ASVG, associated with occlusion (embolism) of the brachial artery (Figure 3). This aneurysm has been replaced with 6 mm PTFE graft Transbrachial thrombembolectomy has been performed too. The pathohistological examination showed a non atherosclerotic origin of the ASVG aneurysm (Figure 4). Three years after secondary operation the PTFE graft is patent. Echocardiography of the same patient showed mitral valve prolaps, probably caused by connective tissue disorder. CASE 4. A 56-year-old female patient was admitted urgently, due to hemorrhagic shock and giant pulsating swelling over the popliteal space. The Duplex ultrasonography and transfemoral angiography showed ruptured popliteal artery aneurysm. This patient had arterial hypertension and higher lipid level. During the urgent operation using dorsal approach, an aneurysm has been replaced with ASVG. A pathohistological examination showed an atherosclerotic origin of the aneurysm. Ten days postoperatively due to bleeding from the wound, a new urgent surgical procedure was performed. Intraoperatively 1 cm long graft laceration was found, while postoperative bacteriological examination showed an infection caused by Staphylococcus Aureus. The graft has been removed, and new extraanatomic, subcutaneous bypass from the superficial femoral to anterior tibial artery using ASVG was performed. Three years later this patient was admitted urgently with giant pulsating mass and skin necrosis at the knee region, associated with hemorrhagic shock. The control angiography showed a ruptured aneurysm of the ASVG (Figures 5 and 6). The aneurysm was replaced with 6mm PTFE graft. The pathohistological examination showed an atherosclerotic origin of the aneurysm. Two year postoperatively, the new graft is patent. CASE 5. A 65-year-old man with previous history of arterial hypertension and high serum lipid level, was admitted with pulsating swelling and skin necrosis at the portion on the thigh. Nine years ago the bellow knee F-P bypass with cephalic vein due to occlusive disease has been performed. Transfemoral angiography showed patent graft associated with ruptured fusiform aneurysm at its mid portion. This aneurysm has been replaced with 6mm tubular PTFE graft. The postoperative patohistological examination showed an atherosclerotic changes at the resected aneurysm. This patient was followed two years, and graft is patent., CASE 6. A 62-year-old male patient was admitted urgently, with giant pulsating swelling over the popliteal space and hemorrhagic shock. The Duplex ultrasonography and angiography showed ruptured popliteal artery aneurysm. The patients had previous history of arterial hypertension and higher serum lipid level. The aneurysm has been replaced with ASVG. Pathohistological examination showed an atherosclerotic origin of the aneurysmal sac. Seven days postoperatively, a massive bleeding from the wound due to graft infection, occurred. New urgent operation showed complete graft abrupption at the site of proximal anastomosis, while postoperative bacteriological examination showed a presence of Staphylococcus Aureus. The graft was removed and new extraantomic, subcutaneous bypass from the superficial femoral to the anterior tibial artery with contralateral ASVG, was performed. The patient recovered very well. Five years latter this patient was admitted urgently with large painful pulsating mass in the thigh. The angiography showed and ASVG fusiform aneurysm. The aneurysm has been replaced with 6 mm PTFE graft. The pathohistological examination showed an atherosclerotic origin of the resected aneurysm (Figure 7). Two years after the operation, a new graft is patent. CASE 7. A 78-year-old man with previous history of arterial hypertension and higher serum lipid level, has been admitted with an asymptomatic pulsating swelling of the medial portion on the thigh. Seven years ago the bellow knee F-P bypass with ASVG and exclusion of the poplietal artery aneurysm was performed. The Duplex ultrasonography and angiography showed a fusiform true aneurysm formation at the mid portion of the patent graft. The aneurysm has been replaced with femoro-anterior tibial artery bypass procedure using 6 mm PTFE graft. The pathohistological examination showed an atherosclerotic origin of the aneurysm. This patient died five days after the operation due to myocardial infarction with patent graft. CASE 8. A 65-year-old male with previous history of arterial hypertension and higher serum lipid level, had an elective replacement of the popliteal artery aneurysm. For the reconstruction a PTFE graft was used. Two years postoperativelly this graft occluded due to changes on the crural arteries. From these reasons a new bypass from the superficial femoral to anterior tibial artery with saphenous vein graft, was performed. Nine years later she was admitted with painful pulsating mass of the mid portion of the thigh. The Duplex ultrasonography and transfemoral angiography showed patent graft with fusiform aneurysm formation of its mid portion. The ASVG aneurysm was replaced with 8 mm Dacron graft. A pathohistological examination showed atherosclerotic origin of the ASVG aneurysm. One year latter this graft is patent. CASE 9. A 65-year-old male with previous history of arterial hypertension and higher serum lipid level, has been admitted due to disabling claudications discomfort caused by aorto-iliac occlusive disease. Nine years earlier a right sided aorto-renal bypass with ASVG was performed due to occlusive disease and renovascular hypertension. An translumbar aortography showed occlusion of the aortic bifurcation associated with fusiform aneurysm formation of ASVG (Figures 8, 9 and 10). During the same operation an aorto-bifemoral bypass and repairing of ASVG aneurysm with Dacron grafts, were performed. A pathohistological examination showed atherosclerotic origin of the ASVG aneurysm. One year latter both grafts are patent. DISCUSSION The table 1 shows 45 true aneurysmal formation at ASVG after F-P bypass surgery in cases with occlusive diseases [1-25]. In his famous paper Szilagyi [3] reported a study of the biologic fate of ASVG in 260 patients with F-P bypass procedures, and he found 10 (3.8%) aneurysms. In 1973 De Weese [5] found 4 (1.2%) ASVG aneurysms after 350 F-P reconstructions, while in 1975 Vanttinen [6] found 1 (0.9%) such case after these procedures. In 1987 Yuanagyia [26], and in 1989 Martin [27] described cases of ASVG aneurysmal formation after subclavian artery aneurysm replacement. Yanagyia's patient had a Behcet disease. We also had one case of ASVG aneurysm after subclavian artery aneurysm repair, manifested with hand ischemia due to distal embolization. Gemperle[12]in 1986 decribed ASVG aneurysm which developed 18 years after replacement of the injured brachial artery. Carrasaquilla [28] has in 1972 described a case of ASVG aneurysm formation after replacement of the common carotid artery, while in 1998 Tekeuchi et al [29] described a case of an ASVG aneurysm after subclavian to vertebral artery bypass due to stenotic lesions of the both vertebral arteries. Four years later a giant ASVG aneurysm was found, and successfully resected. In 1990 Peer et al [30] reported two ASVG aneurysms seven and eight years after popliteal artery aneurysm replacement. In 1991 Kogel et al [31] described one such case 10 years after primary operation. In 1997 Loftus [32] described 10 new cases of the ASVG aneurysms after popliteal artery aneurysm repair. We had two such cases developed three and five years after primary operation. In three of our cases ASVG aneurysm showed an atherosclerotic origin, while in 3 non atherosclerotic. The exact mechanism of aneurysm degeneration of the ASVG in arterial position is unknown. There is likely a combination of factors including: - mechanical trauma during vein harvesting and operation [9,30]; - weakness at branching sites in the vein [2,9]; - potential weakness in the vicinity of the venous valves due to absence of the circular muscle cuff in the media of the vessel wall [5]; - infection [16]; - trauma caused by bony structures near the graft [18,30]; - arteritis [13,14,26, 27, 30]; - atherosclerosis [2,3,5-11,18,19,21,24,25]; - hemodinamic factors from the arterial pressure [23]; - transmural ischemie injury of the vein wall due to disrupting of the vasa vasorum after removing of the vein segments [28,29,33]; Brody cold this fenomen „devascularization of the venous graft" [34]; - diffuse nature of this process in patients with multiple aneurysmal changes [20,32] (our cases 2,3,4,6 and 8); - using of the cephalic [9], or superficial femoral vein [1] (case 7); - changed veins (one of our cases). The use of in situ bypass technique for arterial reconstruction would theoretically, minimize endothelial trauma by reducing operative manipulation, preserving vasa vasorum, and eliminating the pressure induced endothelial desquamation that has been associated with mechanical destination of reversed vein graft during their harvest. However, Sassoust [15] in 1986 reported 5 cases of true aneuryms of the ASVG after in situ F-P bypass. After Sassoust's new cases of ASVG aneurysm following F-P in situ bypass surgery were reported [22-24]. CONCLUSION Early ASVG aneurysm formation occurring six months after surgery has been found to be the result of preexisting unrecognized vein wall weakness or injury at the time of harvest, while aneurysm discovered 5 or more years postoperatively, were atherosclerotic in nature. The aneurysms of the ASVG are frequent, at patients with multiple aneurysms of natural arteries. The ASVG aneurysms require active surgical treatment. Then autologous vein grafts are not „material of choice" for replacement of aneurysmally changed ASVG after peripheral vascular reconstructions.