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| {{SI}}
| | #redirect[[Saphenous Vein Graft]] |
| {{WikiDoc Cardiology Network Infobox}}
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| {{CMG}}<br/>
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| '''Associate Editors-In-Chief:''' Jason C. Choi, M.D., Xin Yang, M.D.
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| {{Editor Help}}
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| ==Background==
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| Coronary artery revascularization with [[saphenous veins]] ([[saphenous vein grafts]] or [[SVGs]]) has become a modern surgical standard for the treatment of [[coronary artery disease]]. This technique can be employed when a native [[coronary artery]] is blocked, thus causing a reduction or obstruction in [[blood flow]]. [[Cardiac surgeons]] use the sutured graft to connect the [[aorta]] to the coronary artery beyond the area of obstruction, so that [[blood flow]] may resume.
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| Despite their ability to restore [[blood flow]], [[SVGs]] commonly encounter [[stenosis]] problems. The incidence of [[SVG]] [[stenosis]] is 15-30% one year after surgery, and it increases to 50% 10 years after surgery. Several factors contribute to [[stenosis]] of [[saphenous vein grafts]], including [[intimal hyperplasia]], [[plaque]] formation, and graft remodeling. Additionally, arterialization of the graft accelerates [[atherosclerosis]]. Furthermore, [[atheroma]] found in [[SVGs]] are more friable (easily break into small pieces) and more prone to [[thrombus]] than [[plaques]] found in native vessels. Another reason why SVGs are more susceptible to [[thrombotic occlusion]] is that they lack side branches.
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| Although intervention on a chronic total occlusion of a [[SVG]] may seem like an effective treatment strategy, it is best avoided.
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| ==Goals of Treatment==
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| Primarily, the goal should be to detect and treat a [[SVG]] [[stenosis]] early in the development of [[ischemia]] while the [[SVG]] is still [[patency|patent]]. As long as the [[SVG]] is not completely [[occlusion|occluded]], intervention can be performed.
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| Two additional overall goals of treating [[SVG]] [[stenosis]] include the resolution of symptomatic [[ischemia]] and the prevention/treatment of [[embolism|distal embolization]].
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| ==Treatment Options==
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| There are many different choices to consider when deciding the most appropriate treatment for [[SVG]] [[stenosis]], including [[PTCA]], [[PCI]] with [[bare metal stent|bare metal]] or [[drug-eluting stents]], [[PCI]] with covered [[stents]], embolic protection devices, [[debulking]]/[[thrombus]] removal, and surgical [[revascularization]].
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| ===Percutaneous Transluminal Coronary Angioplasty (PTCA)===
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| [[PTCA]] has high initial [[revascularization]] success rates in the treatment of SVG [[stenosis]]. However, it is also associated with high rates of periprocedural complications, including acute vessel closure secondary to [[dissection]] and in-situ [[thrombosis]]. Additional complications include [[embolism|distal embolization]] and [[no reflow]], which can lead to periprocedural [[infarction]].
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| In modern [[interventional cardiology]], [[PTCA]] is not often used as the sole means of treatment for SVG [[stenosis]]. Instead, [[stenting]] has become the cornerstone of treatment, while the use of [[PTCA]] has been limited to pre-dilation and post-dilation.
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| ===PCI with Bare Metal Stents (BMS) or Drug-eluting Stents (DES)===
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| Most current vein graft treatment strategies utilize PCI with stents ([[BMS]] or [[DES]]), since stenting is a superior treatment when compared to [[PTCA]] alone. As demonstrated in the SAVED (Saphenous Vein De Novo) Trial<ref name="pmid9287229">{{cite journal |author=Savage MP, Douglas JS, Fischman DL, ''et al.'' |title=Stent placement compared with balloon angioplasty for obstructed coronary bypass grafts. Saphenous Vein De Novo Trial Investigators |journal=N. Engl. J. Med. |volume=337 |issue=11 |pages=740–7 |year=1997 |month=September |pmid=9287229 |doi= |url=}}</ref>, the use of [[stents]] is associated with higher [[revascularization]] success rates, decreased [[restenosis]] rates, and improved clinical outcomes when compared to [[PTCA]]. Generally, [[DES]] are preferred over [[BMS]], since [[DES]] are associated with reduced rates of [[restenosis]] and target vessel [[revascularization]].
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| Despite their higher success rates, stents are not immune to [[restenosis]]. Predictors for [[restenosis]] include long [[stent]] length, multiple [[stents]], overlapping [[stents]], smaller vessel size, [[diabetes mellitus]], and [[stenosis]] at the coronary or aortic [[anastomosis]].
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| ===PCI with Covered Stents===
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| Theoretically, [[stents]] covered with a polymer membrane would have higher success rates than standard [[BMS]] and [[DES]]. One would expect covered stents to effectively trap friable [[atheroma]] and isolate the graft [[Lumen (anatomy)|lumen]] from the diseased wall, thereby reducing incidence of [[restenosis]], distal [[embolization]], and [[no reflow]] in comparison to traditional [[stents]]. However, the RECOVERS (The Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts)<ref name="pmid12821546">{{cite journal |author=Stankovic G, Colombo A, Presbitero P, ''et al.'' |title=Randomized evaluation of polytetrafluoroethylene-covered stent in saphenous vein grafts: the Randomized Evaluation of polytetrafluoroethylene COVERed stent in Saphenous vein grafts (RECOVERS) Trial |journal=Circulation |volume=108 |issue=1 |pages=37–42 |year=2003 |month=July |pmid=12821546 |doi=10.1161/01.CIR.0000079106.71097.1C |url=}}</ref> and STING (STents IN Grafts)<ref name="pmid14563575">{{cite journal |author=Schächinger V, Hamm CW, Münzel T, ''et al.'' |title=A randomized trial of polytetrafluoroethylene-membrane-covered stents compared with conventional stents in aortocoronary saphenous vein grafts |journal=J. Am. Coll. Cardiol. |volume=42 |issue=8 |pages=1360–9 |year=2003 |month=October |pmid=14563575 |doi= |url=}}</ref> trials did not show any advantage in using covered [[stents]] when compared to [[bare metal stents]] for [[SVG lesions]].
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| ===Embolic Protection Devices===
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| During [[PCI]] of [[SVGs]], [[Atheroembolism|atheroembolic]] debris can be liberated. This debris contains [[vasoactive]] substances that can contribute to [[no reflow]], which can in turn considerable increase the risk of major adverse clinical events (MACE)<ref name="pmid16264199">{{cite journal |author=Salloum J, Tharpe C, Vaughan D, Zhao DX |title=Release and elimination of soluble vasoactive factors during percutaneous coronary intervention of saphenous vein grafts: analysis using the PercuSurge GuardWire distal protection device |journal=J Invasive Cardiol |volume=17 |issue=11 |pages=575–9 |year=2005 |month=November |pmid=16264199 |doi= |url=}}</ref>. Fortunately, embolic protection devices help capture this debris and improve outcomes in [[PCI]] for [[SVG]] [[stenosis]]. Therefore, they should be utilized in the intervention of most [[SVG]] lesions.
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| Currently, the [[FDA]] has approved five embolic protection devices in the United States. Specifically, these devices include one distal occlusion device, three filters, and one proximal occlusion device.
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| The FDA-approved distal occlusion device is called the PercuSurge Guardwire®, which entails inflating a balloon distal to the [[stenosis]] to occlude flow, thereby trapping the debris and [[vasoactive]] substances and preventing them from flowing downstream. Due to its small size, it requires little landing zone to deploy. The SAFER (Saphenous vein graft Angioplasty Free of Emboli Randomized) trial<ref name="pmid11901037">{{cite journal |author=Baim DS, Wahr D, George B, ''et al.'' |title=Randomized trial of a distal embolic protection device during percutaneous intervention of saphenous vein aorto-coronary bypass grafts |journal=Circulation |volume=105 |issue=11 |pages=1285–90 |year=2002 |month=March |pmid=11901037 |doi= |url=}}</ref> showed that when compared to conventional guidewires, balloon occlusion devices (PercuSurge Guardwire) reduced the rates of infarction and [[no-reflow]] after intervention. Despite these advantages, the PercuSurge Guardwire may not be the best option for all, as some patients may not tolerate the necessary 3-5 minutes of [[ischemic]] time associated with this device. Additionally, it is known to cause both [[hemodynamic]] and arrhythmic complications.
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| Filter devices allow continual distal perfusion while macroscopic [[emboli]] are trapped in the filter. The FIRE (FilterWire EX During Transluminal Intervention of Saphenous Vein Grafts) trial<ref name="pmid12874191">{{cite journal |author=Stone GW, Rogers C, Hermiller J, ''et al.'' |title=Randomized comparison of distal protection with a filter-based catheter and a balloon occlusion and aspiration system during percutaneous intervention of diseased saphenous vein aorto-coronary bypass grafts |journal=Circulation |volume=108 |issue=5 |pages=548–53 |year=2003 |month=August |pmid=12874191 |doi=10.1161/01.CIR.0000080894.51311.0A |url=}}</ref><ref name="pmid16569562">{{cite journal |author=Halkin A, Masud AZ, Rogers C, ''et al.'' |title=Six-month outcomes after percutaneous intervention for lesions in aortocoronary saphenous vein grafts using distal protection devices: results from the FIRE trial |journal=Am. Heart J. |volume=151 |issue=4 |pages=915.e1–7 |year=2006 |month=April |pmid=16569562 |doi=10.1016/j.ahj.2005.09.018 |url=}}</ref> showed that FilterWire may be preferred over PercuSurge Guardwire® due to improved clinical outcomes. While they may reduce [[ischemic]] time, filter devices are associated with their own set of potential complications. They are more difficult to deliver than balloon [[occlusion]] devices, so their own delivery may lead to distal [[embolization]], and they may not trap microscopic mediators of [[no reflow]]. Additionally, they require a significant landing zone distal to the [[lesion]] for the filter placement, which can be problematic for certain distal lesions that do not have enough room. There have also been case reports of filter entrapment in the [[Great saphenous vein#Use in cardiovascular procedures|graft]] after the completion of the [[PCI]].
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| The FDA-approved proximal occlusion device is called the Proxis® device. Some advantages of this decide are that its deployment does not require crossing the [[stenosis]], it provides superior support that is helpful where balloon or [[stent]] delivery is difficult, and it provides protected crossing of the [[lesion]], if required. However, as shown by the PROXIMAL (Proximal Protection During Saphenous Vein Graft Intervention Using the Proxis Embolic Protection System) trial<ref name="pmid17919563">{{cite journal |author=Mauri L, Cox D, Hermiller J, ''et al.'' |title=The PROXIMAL trial: proximal protection during saphenous vein graft intervention using the Proxis Embolic Protection System: a randomized, prospective, multicenter clinical trial |journal=J. Am. Coll. Cardiol. |volume=50 |issue=15 |pages=1442–9 |year=2007 |month=October |pmid=17919563 |doi=10.1016/j.jacc.2007.06.039 |url=}}</ref>, in terms of overall outcomes, there is no significant difference in death, [[MI]], or target vessel [[revascularization]] (TVR) between distal and proximal [[embolic]] protection devices.
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| [[Category:Cardiology]]
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