Percutaneous Coronary Intervention of Chronic Saphenous Vein
Graft Occlusion: A Potential New Paradigm

Case Presentation

A 69-year-old male with a history of hypertension, hyperlipidemia, s/p coronary artery bypass graft in 1994 (saphenous vein graft [SVG] to the right coronary artery [RCA], SVG to the diagonal branch, SVG to the obtuse marginal artery and left internal mammary artery to the left anterior descending artery [LAD]) underwent percutaneous coronary intervention in 2000 with bare-metal stent implantation in the SVG to the RCA due to 90% stenosis at the distal anastomosis. He did well until 3 months prior to his current admission, when he experienced recurrence of exertional anginal symptoms that persisted despite optimization of the medical therapy. He underwent coronary angiography on December 16, 2005 at another hospital and was found to have proximal occlusion of the SVG-to-RCA graft with left-to-right collaterals (Figure 1). Remaining grafts were patent. He was referred to the Lenox Hill Heart and Vascular Institute of New York for revascularization. The patient’s hematocrit was 42.1%; his platelets were 181,000; blood urea nitrogen/creatine was 16/1.4 mg/dl; his total cholesterol was 141 mg/dl (low-density lipoprotein: 79 mg/dl; high-density lipoprotein: 38 mg/dl; triglyceride: 122 mg/dl). Electrocardiography showed sinus rhythm, a heart rate of 58 beats per minute, LAD, left atrial enlargement and non-specific ST-T wave changes. Echocardiographic evaluation revealed normal left ventricular function and wall motion.

Procedure

We elected to perform percutaneous revascularization of the SVG to the RCA with combined distal protection, suction thrombectomy and drug-eluting stents (DES) placement. The patient had been on chronic dual antiplatelet therapy with aspirin and clopidogrel.

Sequence of interventional events:

1. The ostium of the SVG to the right coronary artery (RCA) was cannulated with a 7 Fr Multipurpose guiding catheter.
2. An ASAHI Miraclebros 3 (Abbott Vascular, Abbott Park, Illinois) 0.014 inch x 180 mm guidewire was advanced through theocclusion to the distal native vessel with a Maverick^® (Boston Scientific Corp., Natick, Massachusetts) over-the-wire (OTW) 1.5 mm x 9 mm balloon.
3. The distal vessel lumen was confirmed with contrast injection through the balloon lumen.
4. A Miraclebros 3 wire was exchanged for a 0.014 inch x 300 mm Stabilizer Plus wire (Cordis Corp., Miami, Florida).
5. The Maverick OTW balloon was removed (no dilatation was performed).
6. A Renegade Hi-Flo (Boston Scientific) microcatheter 0.018 inch compatible was advanced to the distal vessel over the Stabilizer Plus wire.
7. An Emboshield BareWire (Abbott Vascular) (315 cm available separately packaged) was advanced to the distal vessel.
8. An Emboshield RX 5 mm filter was advanced to the distal vessel and deployed (Figure 2).
9. The SVG was dilated with a Maverick 2 RX 3.0 x 30 mm balloon.
10. A Pronto™ suction thrombectomy catheter (Vascular Solutions, Inc., Minneapolis, Minnesota) was advanced through the graft to remove debris.
11. Three Taxus 3.5 mm x 32 mm stents plus one 3.5 mm x 12 mm stent were used to optimize the lumen.*
12. Adenosine 12 µg was administered I/graft to optimize distal “run-off”.
13. The Emboshield filter was removed.
14. Final angiography was performed (Figure 3).

There was no evidence of distal embolization or “slow-flow” at any time during the intervention (thrombolysis in myocardial infarction [TIMI] 3 flow, 0% residual stenosis and normal myocardial perfusion grade in the large distal RCA distribution). An Angio-Seal™ (St. Jude Medical, Inc., St. Paul, Minnesota) device was used to achieve femoral hemostasis.
No postprocedural increase of the cardiac markers was noted and the patient was successfully discharged the next day. His symptoms resolved and, since PCI, he has remained asymptomatic. After 1 month, the patient underwent PCI of the OM1. The revascularized graft was widely patent (Figure 4).

Discussion

We report successful PCI of an old, degenerated, restenosed and totally occluded vein graft with the use of a new, OTW distal filter protection device that facilitated placement of the embolic protection filter prior to dilatation and stenting of the graft. Despite the highly complex PCI, excellent angiographic and clinical success were achieved by using this multimodality approach. The novel approach in this case centers on placement of the filter prior to any dilatation of the graft material, simple suction thrombectomy and DES placement.
Although the majority of the 400,000 coronary bypass surgeries performed in the United States each year use at least 1 arterial graft conduit (internal mammary or free radial), most still involve the placement of 1 or more SVGs.¹ Postoperatively, the SVGs began to develop intimal hyperplasia and thickening in response to surgical trauma, a loss of intrinsic vascular supply and exposure of the thin-walled structure to an abrupt increase in wall stress as it is moved from the low-pressure venous to the high-pressure arterial environment. This sets the stage for subsequent atherosclerotic degeneration and superimposed thrombus, causing approximately 50% of these grafts to become occluded 5–10 years after surgery.
Although percutaneous treatment of failing SVGs is generally preferred,² given the generally higher risk of reoperation in an older and sicker patient population and the risk of injuring other patent grafts, PCI for SVG disease continues to be a challenging procedure. The highest-risk group in the cohort of patients with degenerated SVG disease are those with occluded vein grafts.^3–5 So far, no percutaneous modality has demonstrated satisfactory results in the treatment of a chronically occluded vein graft. Large, bulky thrombus that completely occupies the residual vein lumen can be easily dislodged and a large amount of embolic material can be released during the procedure. The risk of distal embolization is especially high, with the “no-reflow” phenomenon being reported in up to 31.8% after PCI of SVGs.⁶
Techniques like selective infusion of urokinase,7 extraction coronary atherectomy,⁸ directional coronary atherectomy,9 laser angioplasty,¹⁰ ultrasound thrombolysis,¹¹ covered stent placement12 and AngioJet rapid thrombectomy¹³ have generally failed in reducing the incidence of complications related to PCI of SVGs. In recent years, certain technical advances have occurred, developments have been made and their combined use, as in our case, may provide successful outcomes in these high-risk lesions.
First, the cause of unsuccessful PCI of an occluded SVG is often failure of the wire to cross the site of the CTO. However, recently developed spring wires dedicated for CTO use have improved success rates.¹⁴ When an occluded SVG is compared with native vessel atherosclerotic disease, there are several pathologic differences. In the case of an occluded SVG, atherosclerosis tends to be diffuse, soft and friable, with a poorly developed or absent fibrous cap that may actually make wire crossing easier. Also, the absence of branches in the SVG favors large and bulky thrombus formation that usually occupies the entire length of the vein and, at the same time, the absence of branches may facilitate the correct direction of the wire in the single, non-branching lumen.
Second, negotiating a total SVG occlusion with the fixed distal protection device wire poses a technical challenge. Initially in the presented case, a standard angioplasty wire (Miraclebros 3) negotiated the occlusion, followed by its exchange with a more supportive wire (Stabilizer Plus) which facilitated the advancement of an infusion catheter that was used instead as a transport catheter for the delivery of the Emboshield filter wire. This is the first reported case of such catheter use for exchange wires in degenerated vein grafts. In our case, the outer surface of the distal segment of the Renegade Hi-Flo microcatheter has a hydrophilic coating and can be easily tracked over a steerable guidewire. This sequence facilitated deployment of the Emboshield catheter prior to any balloon dilatation and potential release of embolic debris.
Third, the Pronto suction thrombectomy catheter — with its ease of use — or other available manual devices, may be used for the successful aspiration of possible embolic material without the risks and disadvantages of the other thrombectomy devices.¹⁵ Furthermore, the application of the Pronto catheter may be more suitable for use in SVGs, given its larger diameter when compared to the Export catheter (Medtronic), making suctioning of the larger thrombotic debris found in occluded veins more efficient.
Fourth, the use of new distal protection devices may allow both better prevention of distal embolization and better stent deliverability when compared to the older devices.¹⁶ The Emboshield filter, which is already used for cerebral protection during carotid interventions, is the only filter to feature the BareWire, a wire that not only can facilitate filter placement, but also may make stent delivery easier once the filter is in place and fully apposed against the vessel wall. The BareWire used by the Emboshield device allows advancement of other large-caliber devices like the Pronto catheter without the need to employ the buddy wire method.
Finally, aside from acute procedural safety, percutaneous vein graft treatment, especially in the bare-metal stent era, is frustrated by a higher rate of restenosis or reocclusion (35–40% vs. 20–25%) over the subsequent 12 to 18 months compared to treated native vessels. About one-half of those failures represent restenosis of the stented site, while the other half represent failure of the treated vessel because of progression of subclinical disease elsewhere than the original stented lesion.^17,18 In our case, the occluded graft had already restenosed 5 years after bare-metal stent placement. Recent reports suggest that DES exert a preventive effect against restenosis, not only in native coronary artery disease (CAD), but also in vein graft lesions.^19–21
Because the mechanism of in-stent restenosis in vein grafts is also neointimal hyperplasia, and the response of in-stent restenosis to brachytherapy is similar, one may assume that DES confer a similar benefit to that seen in native vessels, but studies on this are not yet available. Although more definitive data from controlled trials are required, it seems that at this point, the best treatment for a degenerated occluded SVG is probably the use of a DES.
One important limitation needs to be mentioned: no data exist regarding the long-term outcome of DES implantation in occluded SVGs. In our case, surveillance evaluation with a nuclear single photon emission computed tomography stress test 9 months after the PCI failed to reveal ischemia. Furthermore, the patient remains symptom-free with unlimited exercise tolerance 1 year after the revascularization procedure, and no recurrence of his previous disabling symptoms.

Conclusion

PCI of chronically occluded SVGs may provide the best revascularization option in certain patients with “end-stage” CAD. The success of this procedure has traditionally been severely limited by guidewire access to the distal native vessel, embolization of the subtended myocardium during revascularization and a high rate of restenosis and reocclusion.
The recent availability of improved guidewires, BareWire distal embolization protection devices, thrombectomy catheters and DES have facilitated the performance of PCI in occluded SVGs.

References

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