• Svg pathology.• Natural course.• Problems in interventions.• Techniques.• Procedure related complications.• Role of stents and supportive medications.
Patients who experience recurrence of ischemia after CABGlesions in – saphenous vein graft (SVG). – native arteries. – internal mammary. – Radial. – gastroepiploic graft. – proximal subclavian artery.
Early postoperative ischemia (<1 month):• acute vein graft thrombosis (60%).• incomplete surgical revascularization (10%).• kinked grafts.• focal stenoses distal to the insertion site and at the proximal or distal anastomotic sites.• spasm or injury.• insertion of graft to a vein causing AV fistula.• bypass of the wrong vessel.• all above cxs are common after minimally invasive and “off-bypass” techniques)
Early postoperative ischemia (1 month–1 year):• peri-anastomotic stenosis.• graft occlusion.• mid-SVG stenosis from fibrous intimal hyperplasia.• Recurrence of angina at about three months postoperatively is highly suggestive of a distal graft anastomotic lesion and in most cases, lead to evaluation for PCI
Late postoperative ischemia (>3 years after surgery):• the most common cause of ischemia is the formation of new atherosclerotic plaques which contain – foam cells, – cholesterol crystals, – blood elements, – necrotic debris as in native vessels.• However, these plaque have less fibrocollagenous tissue and calcifi cation, so they are softer, more friable, of larger size, and frequently associated with thrombus.
• The status of the LAD and its graft significantly influences the selection process.( because lack of survival benefit of repeat surgery to treat non-LAD ischemia.)
Interventions within hours of C.A.B.G:• urgent coronary angiography may reveal a compromised graft.• Once a graft is thrombosed-------opening of the native vessel is preferable.• if the native vessel is not a reasonable target------------- balloon interventions (thrombectomy device) on the graft are also effective if thrombus formation is not extensive.
• ? Intracoronary thrombolytic therapy-1/3rd requiring mediastinal drainage due to bleeding.
Native coronary interventions• One year after C.A.B.G, – patients begin to develop new atherosclerotic plaques in the graft conduits or – show atherosclerotic progression in the native coronary arteries.
Approaches to native vessel sites in post-bypass patients• Treatment of protected left main disease.• recanalization of old total occlusion or• native artery via venous or arterial grafts.
Intervention of the aorto-ostial lesion• there is a question about need of prior debulking followed by stenting or stenting alone of the aorto- ostial lesion.• In a study by Ahmed et al. for both groups of patients with or without prior debulking, the TLR rate after one year was similar at 19%.• The technical concern during PCI of large and bulky aorto-ostial lesion is the antegrade and retrograde embolization.• There is distal protective device for antegrade embolization but there is none for retrograde embolization
Saphenous vein graft interventions• 1-3yrafter surgery, patients begin to develop atherosclerotic plaques in the SVG.• after 3 years, these plaques appear with increased frequency.• At the early stage, dilation of the distal anastomosis can be accomplished with little morbidity and good long-term patency (80–90%).• Dilation of the proximal and mid-segment of the vein graft was highly successful at 90%, with a low rate of mortality (1%), Q-wave MI, and CABG(2%).• The rate of non-Q-wave MI was 13%.
Intervention in degenerated saphenous vein grafts:• The lesions that are bulky or associated with thrombus are considered to be high-risk.• The complications include distal embolization, no-refl ow, abrupt closure, and perforation.• So different approaches were devised because there is much to lose from the standpoint of distal embolization causing non-Q MI and increasing long-term mortality.• In the case of perforation of SVG, usually there is contained perforation rather than cardiac tamponade due to the extrapericardial course of the grafts and extensive post- pericardiotomy fi brosis
Rheolytic thrombectomy Dissolution and removal of Hypo tube clots from coronary and peripheral arteries is achieved by the creation of a flow- mediated vacuum in the Water vicinity of the treated lesion. jets Exhaust lumen High speed injection of saline fluid into an aspiration catheter forms a low pressure zone at its orifice (the Bernoulli effect).
The pressure gradient between the thrombus and the catheter tip draws clot particles into the lumen of the device, where they are further fragmented by the high speed saline jets and then aspirated. The double lumen device allows both saline injection and aspiration of particulate matter into its collection system.
In the VeGAS 2 trial, the 40% Angiojet device was compared 30% 33.1% with urokinase prior to Angiojet 30.8% percutaneous treatment of 346 20% Urokinase patients with thrombus-rich lesions in native coronary 13.9% 15.0% 10% arteries or SVG’s. 1.7% 3.0% 0% Death MI MACE In this high risk population, 20.0% Angiojet procedural success and Urokinase hospital course without a major 15.0% adverse cardiac event were 13.6% achieved with the Angiojet 10.0% 11.8% catheter in 86% of cases, significantly more frequently 5.0% than with urokinase (66%, P = 3.3% 0.01) 0.0% 3.3% 0.6% 3.0% Any Surgical Repair Transfusion
Aspiration thrombectomy The X-Sizer (EndicCOR Medical, Inc.,) is a thromboatherectomy catheter of varying dimensions. Rotation of a distal helical cutter results in thrombus maceration and extraction into a distal vacuum collection bottle. Experience in several hundred pts has shown this catheter to be effective in debulking thrombus and degenerating SVG lesions .
The X-TRACT trial demonstrated that the X- X-SIZER Control Sizer may be safely used as an 25 adjunct to PCI of diseased SVGs and thrombus-laden 20 native coronary arteries. 16.9 17.0 17.4 15.8 15 Less need for GP IIb/IIIa Incidence (%) inhibitor bail-out in patients 10 treated with the X-Sizer, suggesting a reduction in periprocedural complications. 5 1.0 0.3 1.8 1.5 MACE rates at 30 days were 0 similar in both groups Cardiac MI TVR MACE death There was a significantly lower incidence of large postprocedural MI at 30-day follow-up among patients treated with the X-Sizer device.
• In general, the X-Sizer system is more effective in removing thrombus and atheromatous debris .• while the AngioJet system was effective only in the removal of fresh thrombus, and not the friable, grumous vein graft material or older organized thrombi
SAFER Trial – Comparison ofPercuSurge to Routine Stenting in SVG’s 801 Patients Randomized 20 30 Day MACE 16.5% Reduced 42% P<0.001 9.6% % 0 Routine PercuSurge Baim et al. Circulation 2002; 105: 1285.
The 800 patient multicenter randomized SAFER trial demonstrated a 50% reduction in in-hospital adverse events with PercuSurge distal protection during SVG stenting, when compared to stenting without protection Preliminary experiences with the PercuSurge in AMI patients undergoing percutaneous intervention suggest that normal myocardial blush may be achieved in more than 60%
PercuSurge SystemAdvantages Disadvantages Captures smaller Transient occlusion particles and Long “parking” “humoral” mediators segment Frequently applicable Side branches unprotected Two operators
In Filter wire-type devices, An emboli entrapment net is mounted on a 0.014" guidewire and expanded distally to the lesion. Intervention is then performed over the guidewire. Filters do not block distal blood flow when first deployed unlike occlusive devices. Dislodged material is caught by the distal filter, which is then closed and retracted only at the end of the procedure.
Fire Trial: Randomized BSC/EPI Filter vs. PercuSurge in SVGPCI 650 patients in 65 sites FW GWTIMI 3 Flow 95.7% 97.7%Device Success 95.5% 97.2%Death 0.9% 0.9%MI 9.0% 10.0%QMI 0.9% 0.6%30 day MACE 9.9% 11.6% Conclusion: FW not inferior to GW Stone et al. J Am Coll Cardiol 2003; 41: 43A
PROXIMAL OCCULUSION DEVICES These devices occlude flow into the vessel using a balloon on the tip of or just the tip of catheter Two proximal occulusion catheters are in use:Proxis catheterKerberos embolic protection system
Proxis In Vessel With inflow occlusion , retrograde flow generated by distal collaterals or infusion through a ”rinsing “ catheter can propel any liberated debris back into the lumen of the guiding catheter These have potential advantage of providing embolic protection even before the first wire crosses the lesion.
Benefits to Proximal Protection Nothing crosses the lesion prior to protection Protection of main vessel and side branches Captures large and small particles Can handle large embolic loads
• Is there a role for 2b3a inhibitors in SVG interventions ?