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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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| ===Debulking/Thrombus Removal===
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| Data has not demonstrated a durable clinical benefit associated with [[debulking]]/[[thrombus]] removal. However, there are certain situations in which [[debulking]] techniques may be useful when treating [[saphenous vein grafts]]. For instance, severely [[calcified]] and [[stenotic]] [[lesions]] can make regular [[stent]] insertion especially difficult. When [[SVG]] [[lesions]] are too [[calcified]] to be crossed by a balloon or adequately dilated prior to [[stent]] placement, [[debulking]] and [[thrombus removal]] can change the compliance of the vessel wall. In addition, this technique is also useful if a [[lesion]] is at the aorto-ostial junction. Adjunctive stenting leads to better short and long term results.
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| There are several [[debulking]]/[[thrombus]] removal techniques, including directional coronary atherectomy, transluminal extraction catheter thrombectomy, rotational atherectomy, and laser atherectomy.
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| * Directional coronary atherectomy (DCA) uses a circular cutting blade that excises [[atheroma]] into a chamber for removal. It is useful for aorto-ostial [[lesions]] and focal [[lesions]] in large vessels. However, due to its bulky nature, it is generally not used in vessels with [[angulation]], [[tortuosity]], or heavy [[calcification]]. CAVEAT II (Coronary Angioplasty Versus Excisional Atherectomy Trial) examined how PTCA and DCA compared in the treatment of patients with coronary artery bypass graft stenoses<ref name="pmid7895354">{{cite journal |author=Holmes DR, Topol EJ, Califf RM, ''et al.'' |title=A multicenter, randomized trial of coronary angioplasty versus directional atherectomy for patients with saphenous vein bypass graft lesions. CAVEAT-II Investigators |journal=Circulation |volume=91 |issue=7 |pages=1966–74 |year=1995 |month=April |pmid=7895354 |doi= |url=}}</ref>. This study demonstrated that DCA was associated with higher initial angiographic success rates and larger acute luminal dimensions in comparison to PTCA. Despite these successes, DCA also displayed an increased rate of non-Q wave myocardial infusion and distal embolization than PTCA. Furthermore, both techniques displayed similar restenosis rates.
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| :Additionally, a retrospective study compared DCA vs. [[PTCA]] alone vs. [[PCI]] with stenting in [[SVG]] lesions. It showed no differences in mortality, [[angina]], [[infarction]], or repeat [[revascularization]] among the different methods. However, this study displayed increased angiographic complications with DCA use.
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| * Transluminal extraction catheter (TEC) thrombectomy is designed to remove [[thrombus]] from [[SVGs]] prior to stenting. It operates through the use of cutting blades with a rotating catheter and an external suction device. However, because the TEC Best trial showed no benefit of TEC prior to the stenting of [[SVGs]], this technique has fallen out of favor. Furthermore, TEC is also associated with a significant incidence of distal [[embolization]] and [[no reflow]].
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| * Rotational atherectomy (RA) uses a rotating cutting blade to grind [[calcified]] [[atheroma]]. Despite its ability to grind [[calcification]], this method is associated with high rates of [[no reflow]], distal [[embolization]], [[perforation]], and [[dissection]]. Furthermore, this method is [[contraindicated]] for [[lesions]] located in the body of [[SVGs]] or in degenerated vein grafts.
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| * Laser atherectomy uses [[monochromatic]] light energy to disrupt [[plaques]]. Despite this approach's innovation, there is no evidence that this strategy improves outcomes in lesions, and it has been complicated by high rates of [[dissection]] and [[perforation]].
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| ===Surgical Revascularization===
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| Given increased perioperative mortality, this is not an optimal treatment strategy as many patients with [[graft disease]] are poor surgical candidates. However, surgery may be required in patients with multi-vessel disease and when [[PCI]] fails.
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| Additionally, reoperation is not strongly encouraged, as it does not provide the same level of [[revascularization]] and resolution of [[angina]] as the initial procedure. Furthermore, a [[LIMA]] may be jeopardized in a reoperation.
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| ==Making a Selection==
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| At the earliest signs of recurrent [[ischemia]], it is important to strongly consider the possibility of a patent but [[stenosed]] [[SVG]], so that the graft [[lesion]] can be treated before the graft becomes completely [[occluded]]. Prompt treatment is essential, since a graft is lost once it becomes completely occluded.
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| Regardless of treatment choice, all patients should be given [[statins]] and [[aspirin]] (begun immediately following [[CABG]]), which are effective in the secondary prevention of [[SVG]] [[stenosis]].
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| For most [[SVG]] [[lesions]], [[PCI]] with [[stenting]] appears to be the therapy of choice. [[DES]] are associated with a decreased [[restenosis]] rate over [[BMS]], and should be used preferentially if the patient is able to tolerate dual platelet therapy for a minimum of a year. Furthermore, [[embolic]] protection devices should be strongly considered for all [[SVG]] [[lesions]], especially those with high risks for distal [[embolization]].
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| In cases in which [[stent]] delivery and expansion may be difficult due to heavily [[calcified]] and [[stenotic]] [[lesions]], atherectomy devices, used with stenting, may be considered. Furthermore, these devices can be useful in [[lesions]] that are aorto-ostial.
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| Zoghbi et al. conducted a study to investigate the role of pretreatment with [[nitroprusside]] before [[SVG]] intervention<ref name="pmid19182287">{{cite journal |author=Zoghbi GJ, Goyal M, Hage F, ''et al.'' |title=Pretreatment with nitroprusside for microcirculatory protection in saphenous vein graft interventions |journal=J Invasive Cardiol |volume=21 |issue=2 |pages=34–9 |year=2009 |month=February |pmid=19182287 |doi= |url=}}</ref>. They studied sixty-four consecutive patients with normal preprocedural cardiac [[enzymes]] that underwent SVG PCI, without the use of [[embolic]] protection devices. They found that pretreatment with [[nitroprusside]] results in a lower magnitude and frequency of post-procedural cardiac [[enzyme]] elevation. Thus, it is worthwhile to consider nitroprusside use.
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| Finally, while GP IIb/IIIa inhibitors are frequently used in the setting of SVG intervention, their benefit has not been fully evaluated in randomized trials of this lesion subset.
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| ==Anticipated Outcomes==
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| With proper treatment, resolution of both symptomatic and asymptomatic [[ischemia]] is expected.
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| ==Other Concerns==
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| As with all medical procedures, complications for SVG intervention can occur. Risk factors for complications include: older graft age (>3-5 years), the presence of a thrombus, and diffuse disease.
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| Although PCI with stenting is effective for focal lesions, there is uncertainty regarding the best treatment for diffusely degenerated SVGs. In these cases, it is often a better choice to abandon the graft and intervene on the native vessel instead.
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| ==References==
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