Subintimal Snare-assisted Dissection for Iliac Recanalization: A Potentially Useful Tool

Introduction

Iliac stenting for occlusive atherosclerotic disease is an accepted therapeutic modality. Completely occluded iliac arteries can be wire recanalized with a high degree of success¹ and acceptable long-term results. The technical aspects of crossing an iliac chronic total occlusion (CTO) can however remain challenging. We describe a novel technical modality to facilitate wire recanalization in difficult cases.

Case Report

A 60-year-old Hispanic male presented with right-sided buttock and thigh claudication after walking one block. Risk factors for peripheral vascular disease included hypertension, hyperlipidemia, and non-insulin dependent diabetes. He also had a past history of smoking. He reported erectile dysfunction. He had no renal insufficiency with a creatinine of 0.8 mg/dL. Physical examination revealed non-palpable right femoral and distal pulses. Left side pulses were normal. No iliac bruits were audible. Ankle brachial pressure indices were 0.51 and 0.67, and on the right and left, respectively. A magnetic resonance angiogram was obtained revealing a right common iliac occlusion and mild left common iliac stenosis. The patient felt limited by this problem and the decision was made to intervene. Percutaneous retrograde access was achieved in the right common femoral artery and the patient was anticoagulated with intravenous heparin. A sheath angiogram confirmed patency of the external and internal iliac arteries as well as the distal 1 cm of the right common iliac artery. A soft 0.035" Glidewire (Terumo, Tokyo, Japan) could not be advanced past the cap of the occlusion, and a straight, stiff 0.035" Glidewire, supported by an angled 5-Fr diagnostic catheter, was substituted. Attempts to keep the wire intraluminal were not successful and a subintimal plane was created cephalad to the lateral aortic wall. The true lumen could not be reentered. Hence, access was achieved in the left common femoral artery with a 6-Fr sheath, and a stiff 0.035" Glidewire supported by a Sos 5-Fr catheter was used to break the cap of the occlusion in the proximal right common iliac artery stump using a contralateral approach. This resulted in subintimal wire entry and advancement.

Despite the use of a variety of angled and straight wires, as well as a variety of catheters including Cobra tips and Spectranetics QuickCross catheters, the distal true lumen of the right iliac artery could not be entered. At this time, the decision was made to try to snare the subintimally located guidewire. Hence, using the right femoral approach, the catheter of the Amplatz snare (Microvena, White Bear Lake, Minnesota) was advanced partially into the occluded common iliac artery in a retrograde direction, and a 25 mm Amplatz gooseneck snare advanced into the subintimal space. The snare was used to dissect the plane widely and grab the wire being advanced from the left groin in an up-and-over fashion, achieving “flossing-technique”.² Once this was achieved, kissing wires could be placed following catheter exchange over the floss wire. The right iliac artery was then debulked using the Spectranetics laser (Spectranetics, Colorado Springs, Colorado) with 2 passes of a 1.4 mm probe, followed by deployment of balloon-expendable kissing stents. The patient regained palpable femoral and distal right side pulses. No closure devices were used. He was seen in follow up with improved walking distance, but erectile dysfunction was persistent.

Discussion

When trying to cross an iliac CTO, two major options exist: intraluminal or subintimal wire passage. The long-term results do not differ much and either method is acceptable.³ Often shorter occlusions can be crossed intraluminally whereas more chronic and longer occlusions require subintimal wire passage. Either approach can be done in a retrograde or up-and-over antegrade fashion. Often a combination is needed.⁴ When trying to penetrate the cap of an occlusive plaque, blunt microdissection devices such as the Frontrunner (Johnson & Johnson, New Brunswick, New Jersey) are available.⁵ It is not clear whether such devices promote staying in the true lumen or lead to a subintimal plane. A radiofrequency-associated device (SafeCross) designed to keep the wire in the true lumen was marketed for a while but is no longer available for use. With subintimal wire passage, another technical hurdle is achieving proper reentry of the wire in the true lumen. This is more difficult if the arterial segment in question is patent but diseased. Often, lumen reentry can be achieved by wire manipulation alone, such as straightening the wire loop used for the subintimal dissection or using an angled catheter straight wire or reverse combination. However, such techniques have a finite success rate, and failure to reenter the true lumen is not an uncommon cause of failure of endovascular management.

In order to help with this problem, a number of techniques have been described. One technique described involves leaving one wire, usually an 0.014" wire, in the false lumen and trying to reenter the true lumen with another 0.014" wire of different tip and bend configuration. The reason is that once a plane of dissection has been created, the natural tendency is for any wire to follow that plane; the role of the first wire is therefore to occlude that path of least resistance. Other advanced techniques include the use of the Outback catheter (Cordis Endovascular, Warren, New Jersey), which fluoroscopically guides a needle from the false to the true lumen.⁶ The success rate of the Outback has been reported at around 50%.⁷ Its use in the iliac system in a retrograde fashion is also associated with a risk of vessel wall perforation and serious bleeding. While that risk also exists in the femoral system, the consequences of such mishaps in the latter case are not as severe. In order to address the latter concern, an intravascular ultrasound-assisted method of identifying the true lumen is available with the Pioneer catheter (Medtronic, Santa Rosa, California). Its use has been reported in the periphery.⁸

Recent reports have shown 100% success with chronic iliac artery occlusions, but still they reported bleeding from the recanalization and angioplasty site that occurred in four patients (15%).⁹ The Pioneer system was not available at the time. Our patient presented a difficult situation. Both antegrade and retrograde approaches resulted in subintimal entries, albeit in different planes that did not communicate. One technique described in the literature for such scenarios is to dilate the dissection plane with angioplasty balloons, followed by wire snaring.¹⁰ We modified this approach and used blunt advancement of a large-size gooseneck snare into the subintimal space to develop this plane and simultaneously grab the wire coming up and over in a subintimal plane. We thus achieved a “floss-technique” as described in combined femoral and popliteal approaches to subintimal recanalization.²

Since this case, we have used the technique successfully in another second case. We feel the use of a large diameter snare is important because it allows a wider subintimal dissection and makes wire grabbing easier. An alternative snare would be the Expro Elite Retrieval (Radius Medical, Acton, Massachusetts), which has the snare incorporated on the 0.035" wire platform. Another consideration would have been to use brachial artery access in order to gain a more linear approach to cross the iliac occlusion in cases in which multiple access requirements exist.¹¹

In summary, cautious persistence is often beneficial with CTO, especially when combined with technical skills and knowledge of the various tools available.