Saphenous vein graft interventions represent a challenge to interventional cardiologists because of the frequent and unpredictable incidence of distal embolization. Distal embolic protection devices have demonstrated a reduction in the incidence of this phenomenon. As the use of these devices becomes more frequent outside research protocols, the limitations of different devices will become apparent. Thrombus at the site of the distal occlusive balloon of the Percusurge distal embolic protection system was noted in the case described and represents a potential drawback of this form of distal protection.

       Within ten years of coronary artery bypass surgery, up to 66% of saphenous vein grafts either occlude or demonstrate significant atherosclerosis.1 This necessitates either repeat coronary artery bypass grafting or percutaneous coronary intervention for relief of recurrent angina. Distal embolization is a frequent complication of percutaneous coronary intervention in saphenous vein grafts. No reflow, Q-wave and non-Q wave myocardial infarction and death can result from graft embolization. The threat of embolization is unpredictable and has not been mitigated by device selection. Embolization is observed following angioplasty, atherectomy and stent implantation. Independent predictors of distal embolization include diffuse degeneration within grafts and a large plaque volume.2

Figure 1

Left anterior oblique projection of the diagonal graft demonstrating a filling defect at the site of the distal occlusion balloon and a 5 mm stent across the lesion in the proximal graft.

Figure 2

Left anterior oblique projection of the graft with the continued presence of the filling defect at the distal balloon site following completion of the interventional procedure. The tip of the Guardwire is visualized in the guiding catheter.

Figure 3

Final angiography demonstrating distal migration of the filling defect noted on the earlier images.

       Distal protection devices have shown a reduction in both macroscopic and microscopic embolization during vein graft interventions. One such device is the Percusurge Guardwire (Medtronic AVE, Santa Rosa, California) distal embolic protection device. The SAFER (Saphenous Vein Free of Emboli Randomized) trial demonstrated that 30-day major cardiac adverse events in the group of patients randomized to the guardwire was reduced by 9.9% compared to the group who had the intervention without the guardwire.3
Potential thrombus formation or plaque disruption at the site of the distal protection balloon is a potential limitation of this device. Angiographic demonstration of this occurrence is highlighted in this case report.

       Case Report. A 77-year-old male with long-standing hypertension and hyperlipidemia, and a prior history of coronary artery bypass grafting 14 years prior presented with recurrent angina and an abnormal myocardial perfusion scan demonstrating ischemia in the distribution of the diagonal artery.
       Angiography demonstrated a high-grade discrete lesion in the mid-portion of the vein graft supplying the diagonal artery. Percutaneous intervention was performed on an ad hoc basis following diagnostic angiography. Due to the “age” of the graft and underlying left ventricular dysfunction, a decision to use a distal protection system device was made. Beyond the distal anastomosis, the graft supplied 2 diagonal arteries of small to medium caliber.
       An 8 French MB-1 guiding catheter (Medtronic AVE) was used to engage the ostium of the vein graft. An exchange-length Percusurge GuardWire was used to cross the lesion and then placed beyond the graft in the proximal native diagonal vessel. The occlusion balloon itself was in the distal portion of the vein graft. With the balloon inflated to 5 atmospheres (atm), absence of antegrade flow through the graft was confirmed. A 5 x 13 mm Ultra Stent (Guidant Corporation, Santa Clara, California) was deployed at 14 atm at the lesion site without predilatation.
       At the time of stent placement, a filling defect was noted at the site of the distal occlusion balloon. This filling defect persisted in spite of due diligence taken to ensure that there was no dead space between the export catheter and the occlusion balloon. Activated clotting time was noted to be 308 seconds, suggesting adequate anticoagulation. With the next contrast injection, this “defect” migrated distally without any deleterious effects on flow characteristics in the graft. The patient was discharged the next day without any post-procedural elevation in markers of myocardial necrosis.

       Discussion. Embolic protection devices are classified into those that are placed proximal or those that are placed distal to the reference lesion. Proximal embolic protection has the advantage of not having to cross the lesion with a wire or filter, thus preventing embolization during initial passage across the lesion. An example of this form of protection is the Parodi system used in carotid interventions. With this system, transient flow reversal in the carotid artery is noted. The system is more cumbersome and has not been tested in the coronary circulation or in randomized trials thus far.
       Distal embolic protection devices rely on the use of balloons and filters to trap and remove debris during intervention. The Percusurge emboli containment system is one such system, and the only FDA-approved embolic protection system.
       This system consists of a distal 0.014´´ nitinol wire (GuardWire) with a compliant balloon 3.5 cm proximal to the terminal end of the wire. This balloon is inflated at 2–5 atm, depending on the vessel diameter. While inflated, standard passage of interventional hardware is possible either over the wire or in a monorail fashion.4
       During in vitro testing of this balloon using scanning electron microscopy, porcine coronary artery segments were found to have denuded endothelium when the vessel wall damage was assessed. Aspirate analysis of export catheter samples also confirmed the presence of endothelial segments.4
       In spite of all precautions (< 5 minute occlusion time, occlusive balloon inflation pressure and adequate anti-coagulation), a filling defect at the site of the distal balloon inflation was noted. This filling defect could represent plaque disruption or thrombus formation. Since the patient tolerated the occlusion time without adverse effects, a thrombectomy trial would have been an alternative way to aspirate all debris and new thrombus rather than observing distal embolization. However, no adverse consequences of the distal embolization of this “filling defect” were seen. This potential drawback of the Percusurge distal protection system is highlighted in this case.
       As the technology of distal protection evolves, filters and second-generation devices will become available in clinical trials. These devices need to be compared with newer techniques, such as direct stenting and the use of covered stents in vein grafts, before widespread use.5

1. Bourasa MG, Fisher LD, Campeau L, et al. Long term fate of bypass grafts: The Coronary Artery Surgery Study and Montreal Heart Institute Experience. Circulation 1985;72(Suppl V):V71–V77.
2. Ming WL, Douglas JS, Lembo NJ, et al. Angiographic predictors of a rise in serum creatine kinase after balloon angioplasty of saphenous vein coronary artery bypass grafts. Am J Cardiol 1993;72:514–517.
3. Baim DS, on behalf of the SAFER Trial Investigators.
4. Oesterle SN, Hayase M, Baim DS, et al. An embolization containment device. Cathet Cardiovasc Intervent 1999;47:243–250.
5. Grube E, Webb J. The Safe Study. Multicenter evaluation of a protection catheter system for distal embolization in coronary venous bypass grafts. J Am Coll Cardiol 1999;33:37A.