852 tomy without using sutures. To use the system, the vein is loaded onto a transfer sheath of the aortic connector, guided to the end of the sheath where it is then pierced by several hooks around the vein graft circumference (1, 2). Previous studies have shown a mean loading time for the vein onto the aortic connector of 4.6-7.7 min with a device deployment time to complete mechanical anastomosis of less than 1 min (14). The Symmetry connector device thus has the potential to reduce operative time and perioperative neurologic sequelae. Since gaining FDA approval in May 2001, more than 30,000 Symmetry Aortic Connector systems have been used and em- erging reports have established safety of this device and the overall patency rates appear to be equivalent to historic suture- mediated anastomosis control although large randomized trials are lacking. However, early bypass graft failures have been reported with some patients requiring redo CABG, or revascularization by percutaneous intervention and stenting (15). In addition there was also intraoperative fatal complications resulted in the deaths of two patients (7). Donsky and associates described two cases of acute thrombotic occlusion of the aortic ostia and hypothesized that this complication may have a similar pathophysiology to that of acute stent thrombosis (8). Car- rel et al. also decided to interrupt the use of the Aortic Con- nector system for the following reasons. 1) The recruitment of the patients was difficult. 2) The rate of stenosis observed was not acceptable, similar to that observed in the early days of intracoronary stenting. 3) A new generation of St. Jude proximal connectors that eliminate the major disadvantages of the present device have been released for investigational purposes (14). In immediate post-operative coronary angiograms or 3-D CT, we failed to observe evidence of connector site stenosis or occlusion, although these have been reported by others. However, in the 6-month follow-up study, we identified 3 cases of ostial saphenous vein graft stenosis and the graft steno- sis in the midportion or in the entire length of the saphenous vein graft in 5 patients in which the ostial site was widely patent. In order to use the aortic connector system, a saphenous vein must be harvested without any surrounding tissue, which has high collagen content and may thus act as a buffer against pulsatile stress with the adventitia. Tsui et al. suggested pre- servation of the adventitia as well as surrounding fat by har- vesting with a ‘no-touch’ might improve vein graft patency with integrity of endothelium and nitric oxide synthase (15). Furthermore, saphenous vein, which is harvested with ske- letonized pattern, would be slid over a transfer sheet thus facil- itating the loading process on the release tube. At this point care must be taken to ensure that the vein is adequately hu- midified and that it is transferred smoothly. The fate of bypassed graft depends on many factors, includ- ing technical faults in harvesting, handling and fashioning the conduits; thrombosis, myointimal hyperplasia, fibrosis C.H. Chung, J.W. Lee, J.K. Kang, et al. and a rapidly progressing variety of atherosclerosis (16). And it is difficult to prove scientifically whether stenosis in the midportion was caused by endothelial damage during the manipulation of the saphenous vein before deploying or by the remodeling process according to native coronary artery flow, or by the progression of atherosclerosis of the grafted saphenous vein. And before concluding thrombotic compli- cations were the direct results of one or more defects in the Symmetry system, several factors regarding a condition rec- ognized to be a prothrombotic state of the each patient must be considered. However we cautiously hypothesize these obser- vations may suggest possible mechanical trauma during dis- engagement of the delivery sheath and the deployment might cause endothelial damage in any portion of the loaded vein in which perivascular tissue had been already stripped off or at least it might facilitate the progression of the early graft intimal hyperplasia leading to graft failure. And to our knowl- edge, no reports have appeared describing the graft stenosis in the midportion with wide patent ostium since the intro- duction of ACS. When the ACS is used, the proximal anastomosis must be performed first; that is not common to all surgeons. Further- more a bulldog clamp has to be used to clamp the graft once the anastomosis has been performed. We also hypothesize this may damage the endothelium of the graft especially when the saphenous vein is clamped under arterial pressure. Due to reports of early connector site stenosis or occlusion (6-8), we have started a very aggressive post-operative anti coagulation regimen. We used to start warfarin and an anti- platelet agent (aspirin and clopidogrel) for first 6 months to reduce the possibility of acute thrombosis at the proximal connector site and then discontinue coumadine and clopido- grel but continue aspirin. Even though the effect of the use of warfarin and clopidogrel on the absence of an early con- nector site stenosis in our study has to be more thoroughly evaluated, we understand that the pathophysiology of acute thrombosis at the proximal connector site may be similar to that seen in acute stent thrombosis (14). And we also observed 3 cases of ostial stenosis at the 6-month follow up, so, we would strongly recommend the use of warfarin and clopido- grel more aggressively postoperatively even more than 6 months. The Symmetry aortic connector system has several poten- tial advantages over the traditional suturing method. First, the time required to perform the anastomosis is reduced which might shorten recovery time. Second, minimizing aortic ma- nipulation may reduce the risk of embolic events and thus reduce the incidence of neurologic complications (18, 19). In this study we could not observe any neurologic problems in these patients whereas there were 1.5% cerebrovascular events in the other group of patients to whom we did not apply the ACS during the same period, although ACS was selectively used to the patients with pre-existing high risks. However, although we assume that the potential benefits