Percutaneous Treatment of Stent-Graft (Viabahn) Thrombosis Employing a Second Stent-Graft

Abstract: Acute thrombosis is the most common mode of stent-graft failure. Thrombectomy and thrombolysis have inadequate medium-term and long-term results. We propose a new technique for treating acute stent-graft thrombosis by “relining” the thrombosed graft with a second stent-graft. Ten patients were treated with this technique and have been free of any repeat intervention for up to 1 year, showing its feasibility. The Viabahn-in-Viabahn technique needs a larger study to confirm its efficacy and safety.

J INVASIVE CARDIOL 2015;27(5):E65-E67

Key words: stent-graft failure, new technique

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Case Series

Background. Due to high thrombus burden in stent-graft thrombosis (9 mL thrombus in the typical 6 x 300 mm femoropopliteal conduit), there is a high likelihood of distal embolization during mechanical removal despite use of distalembolization protection (DEP). Alternatively, thrombolysis is an overnight procedure fraught with logistic and bleeding issues. Therefore, total exteriorization of thrombus by relining the entire conduit with a new Viabahn covered stent-graft (VB) (Gore Medical) may be an option.

Methods. Ten consecutive patients with acute/subacute VB thrombosis in the superficial femoral artery presenting with critical limb ischemia (CLI) were treated percutaneously by relining the entire thrombosed conduit with the new VB (Table 1). In the first 5 cases, laser thrombectomy was used as initial treatment. No DEP was used. Entry/exit disease was found in all but 1 case, and was addressed during the same procedure (angioplasty or stenting, as deemed appropriate). All patients were on aspirin and clopidogrel at the time of VB thrombosis. All patients were continued on aspirin and clopidogrel at discharge, except for 1 patient who had no inflow or outflow issues as an explanation for his thrombosis and was started on long-term coumadin therapy. Patients were examined at 1, 3, and 6 months, and annually thereafter. Ankle-brachial indexes (ABIs) were checked periodically.

Technique. After angiographic confirmation of a totally occluded previously deployed VB, the lesion was crossed employing standard “wire-balloon” techniques. In the first 5 cases, small-fiber laser thrombectomy (<2 mm catheter diameter) was attempted as the initial approach. However, suboptimal angiographic results prompted us to proceed with the Viabahn-in-Viabahn (VBinVB) technique. In the subsequent 5 cases, we deployed VBinVB ab initio inside the thrombosed VB. No prestent balloon dilation was performed for fear of distal embolization. We used 5-mm diameter VBs in all cases even though some of the thrombosed VBs were 6 mm and some were 5 mm in diameter. The length chosen was longer than the previous VBs to make sure that the edges of the first VB were covered. Once the thrombus was trapped behind the new VB, all patients received postdilation with 5 mm non-compliant balloon at high pressures (14-16 atm). If an edge stenosis was noted after postdilation of the new VB, repeat angioplasty or stenting of that segment was performed. Any significant disease above or below the VB was treated to ensure good inflow and outflow.

Results. Details of the procedures are listed in Table 2. Mean follow-up was 12.2 ± 6.7 months. The minimum follow-up was 4 months for all 10 patients. To date, all VBinVBs have stayed patent, with clinical relief and no recurrent CLI (Table 3). Angiographic images of a thrombosed VB before and after treatment with VBinVB are shown in Figure 1.

Discussion

Endovascular treatment success of long lesions of the superficial femoral artery is limited by a high incidence of restenosis. Stent-grafts reduce the incidence of in-stent restenosis,¹ with several studies showing a 1-year primary patency rate between 44% and 86%, and secondary patency rates between 58% and 93%.^2-5 Randomized studies have shown superiority of the stent-grafts over balloon angioplasty and bare-metal stents,^6,7 and a similar patency rate to surgical prosthetic femoropopliteal bypass up to 48 months.^6,8 Although the overall reintervention rate is lower for stent-grafts compared with bare-metal stents, thrombosis is the most common cause of stent-graft failure and could lead to limb loss.¹ When stent-grafts fail, there is a higher rate of acute limb ischemia and need for thrombolysis.⁹ Acute thrombosis is often preceded by edge stenosis or any significant inflow or outflow disease. In that regard, all patients were scheduled for an early postprocedure (within 1-2 weeks) and quarterly (every 3 months) lower-extremity arterial duplex ultrasound for effective surveillance and early detection of edge stenosis. Thrombectomy and thrombolysis are accepted as initial strategies for acute graft thrombosis.¹⁰ A recent study evaluating efficacy and outcome of thrombolysis and thrombectomy for thrombosed stent-grafts found that 61% of the patients undergoing such treatments needed reintervention within 18 months.¹ Twenty-six percent of patients required vessel bypass surgery and 7% had amputation. The secondary patency rate for the entire cohort of 46 patients was 58% at 1 year. Dealing with thrombosis is an arduous task, as catheter-based manipulation of the thrombus can potentially activate the platelets and worsen the situation. We did not attempt thrombolysis prior to VBinVB implant. Our premise was that trapping thrombus and exteriorizing it may be an effective stand-alone therapy for copious amounts of thrombus. As such, we chose to keep our approach simple and findings clearly interpretable. Our technique aims not at removing the thrombus, but rather simply exteriorizing it from the vascular bed. This was achieved by deploying another VB stent-graft within the previously deployed VB.

As we confirmed with engineers from Gore Medical, the manufacturer of Viabahn, the wall thickness of a Viabahn stent-graft is 0.4 mm. Therefore, in theory, the external diameter of a fully expanded 5 mm Viabahn should be 5.8 mm (5 mm internal diameter plus two walls of 0.4 mm each). We chose a 5 mm VB to treat thrombosis of a 6 mm VB to give the new conduit enough room to fully expand. When the original thrombosed VB was 5 mm to begin with, we had no choice but to use a 5 mm conduit within a 5 mm conduit, since the VB is not available in a 4 mm size. Either way, the relatively fresh thrombus – despite being copious – was effectively trapped behind the new conduit.

Despite the small number of patients we treated, we had excellent results, with 100% primary patency rate at 1 year. Needless to say, we paid meticulous attention to inflow and outflow, as this is probably the most important factor for favorable long-term results. This is a new technique that is simple and has a potential for wide-spread adoption if larger studies confirm our positive experience.

Conclusion

1. The VBinVB technique appears to be a safe, simple, and quick therapeutic option with high success rate, low procedural complication rate, and excellent short-term clinical outcomes.
2. Larger studies with longer follow-up are needed to confirm our findings.
3. There may be a role for this approach in surgical femoropopliteal bypass graft malfunction.

References

1. Golchehr B, Lensvelt M, Reijnen M, et al. Outcome of thrombolysis and thrombectomy for thrombosed endografts inserted in the superficial femoral aretry for occlusive disease. J Endovasc Ther. 2013;20:836-843.
2. Farraj N, Srivastava A, Pershad A. One-year outcomes for recanalization of long superficial femoral artery chronic total occlusions with the Viabahn stent graft. J Invasive Cardiol. 2009;21:278-281.
3. Scheider JR, Verta MJ, Kim S, et al. Results with Viabahn-assisted subintimal recanalization for TASC C and TASC D superficial femoral artery occlusive disease. Vasc Endovascular Surg. 2011;45:391-397.
4. Saxon RR, Chervu A, Rush MJ, et al. Heparin-bonded, expanded polytetrafluoroethylene-lined stent graft in the treatment of femoropopliteal artery disease: 1-year results of the VIPER (Viabahn Endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Aretry Obstructive Disease) trial. J Vasc Interv Radiol. 2013;24:165-173.
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6. Doomernik DE, Golchehr B, Lensvelt MM, et al.The role of superficial femoral artery endoluminalbypass in long de novo lesions and instent restenosis. J Cardiovasc Surg (Torino). 2012;53:447-457.
7. Lammer J, Zeller T, Schoder M, et al. Heparin-bonded covered stents versus bare-metal stents for complex femoropopliteal artery lesions: the randomized VIASTAR trial (Viabahn endoprosthesis with PROPATEN bioactive surface [VIA] versus bare nitinol stent in the treatment of long lesions in superficial femoral artery occlusive disease). J Am Coll Cardiol. 2013;62:1320-1327.
8. McQuade K, Gable D, Pearl G, et al. Four-year randomized prospective comparison of percutaneous ePTFE/nitinol self-expanding stent graft versus prosthetic femoral-popliteal bypass in the treatment of superficial femoral artery occlusive disease. J Vasc Surg. 2010;52:584-590.
9. Vartanian SM, Johnston PC, Conte MS, et al. Clinical consequence of bare metal stent and stent graft failure in femoropopliteal occlusive disease. J Vasc Surg. 2013;58:1525-1531.
10. Berridge DC, Kessel D, Robertson I. Surgery versus thrombolysis for acute limb ischaemia: initial management. Cochrane Database Syst Rev. 2013;6:CD002784.

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From the Department of Cardiology, Newark Beth Israel Medical Center, Newark, New Jersey.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted February 26, 2014, provisional acceptance given June 3, 2014, final version accepted October 15, 2014.

Address for correspondence: Najam Wasty, MD, Department of Cardiology, 201 Lyons Ave, Suite C-2, Newark, NJ 07112. Email: Nwasty@barnabashealth.org