Export Aspiration Catheter-Enhanced FilterWire‚Ñ¢ Delivery: An Innovative Strategy for Treatment of Saphenous Vein Graft Disease

Percutaneous saphenous vein graft (SVG) intervention has a high incidence of distal embolization, usually in the range of 15–20%.^1,2 The release of friable atherothrombotic materials causes the no-reflow phenomenon and myonecrosis, which are associated with increased late mortality.² Embolic protection devices, notably the PercuSurge GuardWire™ system (Medtronic, Inc., Minneapolis, Minnesota) and the FilterWire™ (Boston Scientific Corp., Natick, Massachusetts), have been proven effective in reducing periprocedural ischemic events by trapping and removing debris.^3,4 The latter has the advantage of maintaining coronary flow during the entire interventional procedure. The failure rate of FilterWire delivery is not high.^4–7 The main reasons for failure include a tortuous vessel course or a hyperacute angle between the guide catheter and the SVG ostium. In complex lesions, the “buddy wire” technique and small-sized balloon predilatation may be required. These reflect the suboptimal crossing profile and limited maneuverability of the delivery system. The authors have invented an Export (Medtronic) aspiration catheter (EAC)-FilterWire assembly delivery system that is able to facilitate FilterWire delivery, and carry out active thrombus removal by thrombosuction. Preparation of EAC-FilterWire EZ assembly. The EAC is one of the components of the PercuSurge GuardWire system and is used for removal of thrombus or debris by manual suction. It is a 135-cm long catheter composed of a 0.040-inch aspiration lumen and a monorail lumen capable of accommodating a 0.014-inch coronary wire. A Y-piece is attached to the proximal end of the catheter; the side arm of the Y-piece is connected to plastic tubing and a syringe. Saline flushing is performed using the syringe to eliminate any air bubbles inside the aspiration lumen. The 300-cm long FilterWire EZ consists of a windsock-shaped filter sac made of a polyurethane porous membrane and a flexible nitinol loop mounted on a 0.014-inch coronary wire. The delivery sheath that comes with the FilterWire is removed. The soft wire tip is molded into a desirable curve by the operator. The FilterWire is then carefully back-loaded into the aspiration lumen of the EAC under water until it comes out from the other end through the Y-piece (Figure 1). The FilterWire is withdrawn further until the nitinol loop is retracted and the tip of the wire is completely housed inside the aspiration lumen (Figure 2). Saline flushing is performed again to drive all air bubbles out. The EAC-FilterWire assembly is now ready for use. Case Series Patient 1. An 81-year-old male had cardiovascular risk factors of hypertension and hypercholesterolemia. He had a long history of severe coronary artery disease (CAD) with coronary artery bypass graft surgery (CABG) performed 19 years ago; 4 saphenous vein graft (SVG) conduits were implanted to the left anterior descending artery (LAD), diagonal branch, obtuse marginal (OM) branch and posterior descending artery (PDA). He underwent percutaneous SVG intervention with implantation of a 4.0 x 14 mm bare-metal stent to the SVG PDA proximal graft body 6 years ago. At the time of the intervention, all the other SVGs were totally occluded. He presented again with acute coronary syndrome and ischemic heart failure 2 months ago. Electrocardiography showed ST-segment depression in leads V5–6 and his troponin-I level was elevated (0.44 ng/ml). The patient was successfully stabilized with medical treatment. Coronary angiography showed calcified, long, diffuse critical lesions in the native LAD and left circumflex arteries; the distal right coronary artery was occluded, and there was a thrombus-containing occlusive lesion within the SVG PDA stent (Figure 3). The other SVG remained occluded. His left ventricular ejection fraction was 35% with inferior hypokinesia. Ad hoc intervention was performed. The patient was already on aspirin 150 mg daily for years. Clopidogrel was administered at a loading dose of 300 mg 1 day prior to the interventional procedure and continued at 75 mg daily. Intravenous unfractionated heparin was administered at a dose of 5,000 Units, and the measured activated clotting time was 320 seconds. No glycoprotein IIb/IIIa inhibitor was given. A 7 Fr Right Coronary Bypass guide catheter (Cordis Corp., Miami, Florida) was used to engage the SVG ostium. Roadmap angiography revealed an in-stent thrombus-containing occlusion with TIMI 0–1 flow (Figure 3). A PT2 (light-support) wire (Boston Scientific Corp.) was used to cross the lesion to reach the distal PDA. Continuous manual thrombosuction (primary thrombosuction) was performed twice using an EAC as it was slowly advanced across and withdrawn from the lesion (Figure 4). Subsequent angiography showed improved coronary flow (TIMI 3) with visualization of the distal anatomy (Figure 5). No debris was recovered from the aspirate. A moderately-diseased segment was present in the distal body of the graft. A 300-cm long FilterWire EZ (Boston Scientific) was loaded into the aspiration lumen of the EAC as described in the previous section. The EAC-FilterWire assembly was then advanced slowly across the lesion (Figure 6). The retracted nitinol filter loop was positioned under fluoroscopy in the mid-segment of the graft just before the distal lesion. The filter sac was released by withdrawing the EAC (Figure 7). The PT2 light-support wire was removed. The thrombus-containing lesion was predilated with a 3.0 x 15 mm balloon at 14 atm and stented with a Taxus^® 4.0 x 32 mm stent (Boston Scientific) at 16 atm. The stent was then postdilated with a 4.5 x 15 mm noncompliant balloon at 18 atm. Filter no-reflow was detected right after balloon dilatation (Figure 8). The patient was hemodynamically stable and did not complain of any symptoms. The EAC was advanced again toward the filter sac. Thrombosuction was performed twice, however, no material was detected in the aspirate, and the FilterWire was removed. The SVG was quickly rewired with the PT2 light-support wire, and the distal lesion was directly stented with a Taxus 3.5 x 32 mm stent deployed at 14 atm. The final angiogram revealed an excellent stent result with TIMI 3 flow (Figure 9). A small amount of red thrombus, together with some white debris, were found in the filter sac. The patient was transferred to the coronary care unit for sheath removal and close observation overnight. His cardiac enzymes (creatinine kinase, CK-MB and troponin-I) were checked three times a day postprocedure for 1 day according to standard protocol. There was no enzyme rise and he was discharged the next day. There were no adverse cardiac events when he was seen in the outpatient clinic 4 weeks later. Clopidogrel was prescribed at a dose of 75 mg daily for 6 months in addition to lifelong aspirin therapy. Patient 2. A 68-year-old male who had known severe CAD and CABG performed in 1992 presented with a clinical picture of acute coronary syndrome. He was an ex-smoker and had a prior history of anterior myocardial infarction. Electrocardiography showed 1 mm ST-segment depression in leads V5–6, and his cardiac enzymes were within normal limits. Echocardiography revealed apical hypokinesia, and the patient’s left ventricular ejection fraction was 45%. Coronary angiography showed blocked native coronary vessels: the SVG to the LAD and the diagonal were patent; there was a complex thrombus-containing lesion of 95% diameter narrowing present in the SVG OM graft body. Ad hoc intervention was performed. The patient was already on aspirin and clopidogrel. Unfractionated heparin at a dose of 6,000 Units was administered; the activated clotting time was 310 seconds. Glycoprotein IIb/IIIa inhibition was not used. A 7 Fr Amplatz 0.75 guide catheter was used to engage the SVG ostium. The graft was first wired with a soft coronary wire. An EAC was advanced across the lesion, followed by manual thrombosuction on retrieval of the catheter. No visible material was recovered from the aspirate. An EAC-FilterWire assembly was then advanced over the wire across the lesion to reach the distal SVG body. The filter loop was released after withdrawing the EAC and soft wire. The lesion was predilated with a 3.0 x 15 mm balloon inflated at 14 atm and stented with a Liberte 3.5 x 32 mm (Boston Scientific) at 14 atm. Filter no-reflow phenomenon immediately developed after stent deployment. Repeat attempts of manual thrombosuction were made, but no material was detected in the aspirate. TIMI 3 coronary flow was finally restored after removal of the FilterWire. A small amount of white debris was detected in the filter sac, and a good angiographic result was achieved. Standard postprocedure care and monitoring protocols were followed. The patient had an uncomplicated clinical course and was discharged 2 days after the procedure. Patient 3. A 77-year-old male had a known history of severe CAD with CABG performed 17 years ago. He had disease recurrence in his SVG LAD graft body, and percutaneous intervention and stent placement (3.5 x 15 mm stent) were performed 4 years ago. He presented again with acute coronary syndrome and elevated troponin-I. His left ventricular function was normal. Elective coronary angiography revealed blocked native coronary vessels; the left internal mammary artery graft to the OM and SVG PDA were disease-free, but there was a subtotal occlusive, thrombus-containing lesion present inside the previously-implanted stent. Ad hoc intervention was performed. The patient was already on aspirin and was preloaded with clopidogrel. Unfractionated heparin was administered at a dose of 6,000 Units. No glycoprotein IIb/IIIa inhibition was given. A 7 Fr Amplatz 0.75 guide catheter was used to engage the graft ostium. The SVG was promptly wired with a soft coronary wire, and primary manual thrombosuction was performed using an EAC. No visible material was retrieved from the aspirate. An EAC-FilterWire assembly was then advanced past the lesion, and the filter loop was deployed at the distal part of the SVG body. The SVG in-stent restenotic lesion was predilated with a 3.0 x 15 mm balloon at 14 atm, and a Taxus 4.0 x 32 mm stent was implanted at 14 atm. The stent was then postdilated with a 4.5 x 15 mm high-pressure balloon at 14 atm. There was no occurrence of filter no-reflow, and the FilterWire was simply removed without additional thrombosuction. There was no visible debris material found inside the filter sac. A good angiographic result was achieved with TIMI 3 coronary flow in the SVG. Standard postprocedure care and monitoring were followed, and the patient was discharged without any complications. Patient 4. An 81-year-old male had diabetes mellitus, hypertension and hyperlipidemia as cardiovascular risk factors. He had known severe CAD, and CABG was performed 10 years ago. He presented again with unstable angina with a normal troponin level. Electrocardiography showed no significant ischemic change, and his left ventricular function was normal. Elective coronary angiography showed blocked native coronary vessels, and the SVG LAD and PDA grafts were disease-free; however, there was a thrombus-containing lesion of 80% diameter narrowing in the SVG OM proximal graft body. Ad hoc intervention was performed. The patient was on aspirin and was already preloaded with clopidogrel. Unfractionated heparin was administered at a dose of 6,000 Units. A 7 Fr Amplatz 0.75 guide catheter was used to engage the graft otium. The lesion was wired with a soft coronary wire. An EAC-FilterWire assembly was directly advanced past the lesion (without primary thrombosuction); the filter was deployed in the distal part of the SVG body. The lesion was directly stented with a Taxus 3.5 x 32 mm stent at 14 atm. No filter no-reflow phenomenon developed, thus no additional thrombosuction was performed. The FilterWire was then removed, and no material was recovered in the filter sac. A good angiographic result was obtained. Standard postprocedure care and monitoring protocols were followed. The patient experienced no postprocedure complications and was discharged the following day. Discussion Embolic protection is a hot topic in the field of coronary, carotid and peripheral artery interventions. It can be divided into two major categories. The “active” methods involve the active removal of thrombus using various thrombectomy devices such as the AngioJet^®(Possis Medical, Inc., Minneapolis, Minnesota),^8,9 the X-sizer (ev3, Inc., Plymouth, Minnesota)^10,11 or even guide catheters,^12,13 which have been reported to be effective in reducing thrombus load. The “passive” methods involve the capturing and removal of dislodged thrombus or debris using occlusion balloons or filters. So far, only the passive methods are able to convincingly demonstrate improved clinical outcomes in SVG interventions.^3,4 This case series has clearly illustrated an innovative approach that combined both active and passive methods to treat complex SVG lesions with occlusive thrombus. Three important steps are emphasized: (1) primary thrombosuction; (2) EAC-enhanced FilterWire delivery; and (3) thrombosuction prior to filter retrieval. The clinical and procedural characteristics of these 4 patients are summarized in Table 1. A 7 Fr Amplatz 0.75 or right coronary bypass guide catheter was used to engage the SVG ostium from the left or right aortic wall, respectively. Strong guide catheters are preferred by the authors since they can provide enough support for the delivery of devices without causing back-out of the FilterWire, which otherwise scrapes the vessel wall and dislodges atheromatous material. Primary thrombosuction using EAC before actual primary angioplasty has been described in a small case series; gross thrombi were captured in 75% of the cases.¹⁴ Primary thrombosuction was successful in all of our cases without small-sized balloon predilatation. However, no visible material was recovered from the initial aspirate. This may reflect the inadequate suction force provided by the EAC to dislodge and capture the debris attached to the lesion. The number of cases was too small to draw any definite conclusion. Primary thrombosuction may also help open up a small channel (by the Dotter effect), which allows visualization of distal anatomy, and acts as a feasibility test for subsequent EAC-facilitated FilterWire delivery. Under the principle of intention-to-treat, the success rate of FilterWire delivery is over 85%.^4–7 This figure depends heavily on the lesion complexity and vessel anatomy. In “real-world” circumstances, both the device utilization and successful delivery rates are likely to be lower. The retracted FilterWire (housed within the delivery sheath) has limited flexibility, pushability, crossing profile and maneuverability. Repeated attempts in probing and crossing a thrombus-containing lesion actually predisposes the patient to dislodgement of friable materials. In addition, favorable positioning of the device may not be achievable due to the inability of the wire to reach the very distal part of the vessel. Furthermore, small-sized balloon predilatation was required prior to successful FilterWire delivery in up to 43% of cases.¹⁵ This maneuver may also potentially increase the risk of distal embolization. EAC-facilitated FilterWire delivery was successful in all of our patients. The device is very user-friendly, as it is easy to assemble and accurately deliver under the guidance of a flexible coronary guidewire to any desired site. Filter no-reflow is increasingly recognized in SVG intervention as well as primary angioplasty. It is defined as an impairment of epicardial flow after deployment of a filter device, followed by a sudden increase of > TIMI 1 flow immediately after device removal in the absence of pharmaceutical treatment between the two consecutive contrast injections.¹⁵ The occurrence may be associated with clinical and hemodynamic deterioration. A capture device that plugs full of embolic material is a major underlying pathological mechanism. Porto et al reported an incidence of 40% in a high-risk cohort.¹⁵ In 1 case report, filter no-reflow was reversed by thrombosuction with an EAC.¹ Despite the use of filters, myocardial infarction still occurred in around 8% of the patients.^4–7 The underlying causes may be due to an intrinsic defect in filter design (incomplete apposition of the filter to the vessel wall), distal embolization to the side branch proximal to the filter, or actual overflowing of atherothrombotic material. Thus, thrombosuction prior to filter retrieval is a sound and sensible approach. In this case series, the history of recent acute coronary syndrome and angiographic evidence of thrombus represented a very high-risk cohort predisposed to distal embolization. Filter no-reflow developed, however, only in 2 patients (50%) in whom additional thrombosuction was performed. There was no debris material found in the aspirate. Atheromatous debris was subsequently recovered in the filter sac in these 2 patients. In light of the absence of elevated cardiac enzymes, it is likely that the embolized particles released in the remaining 2 cases were too small for the naked eye. Additional thrombosuction prior to filter removal was not necessary in the absence of filter no-reflow. TIMI 3 coronary flow was seen in all cases after filter retrieval; no glycoprotein IIb/IIIa inhibitors had been used. The mean procedure time was 55.5 ± 5.2 minutes. No stent thrombosis or other adverse cardiac event was encountered in-hospital or 1 month after the index procedure. Owing to a high propensity for distal embolization, distal protection devices have been recommended in percutaneous SVG intervention, irrespective of the presence of angiographically-proven thrombus. The role of EAC-enhanced FilterWire delivery is not to replace the bare FilterWire, rather it should be reserved for complex lesions in which direct delivery of the FilterWire is expected to be difficult. Early experience of this strategy on thrombus-containing SVG lesions has been promising.

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