Re: Right Renal Artery In Vivo Stent Fracture

Abstract

The report of a renal stent fracture by Robertson et al (1Robertson S.W. Jessup D.B. Boero I.J. et al.Right renal artery in vivo stent fracture.J Vasc Interv Radiol. 2008; 19: 439-442Abstract Full Text Full Text PDF PubMed Scopus (31) Google Scholar) illustrates that movement of intraabdominal vessels can be sufficient to result in fracture of balloon-expandable stents in renal arteries. We would like to report an alternative therapy for renal artery stent fracture, and also an unusual case of common iliac artery stent fracture. A 73-year-old woman with renovascular hypertension had a 6-mm × 18-mm balloon-expandable Express stent (Boston Scientific, Natick, Massachusetts) placed in the left renal artery with a satisfactory result. Five months later, the patient presented with recurrent hypertension, and a repeat angiogram revealed that the stent had a severe restenosis (Figure,a) where the stent had fractured into two separate segments (Figure, b). Fluoroscopy demonstrated substantial respiratory movement of the left kidney with flexion occurring between the two stent fragments. To restore renal artery patency and still prevent repeated stent fracture, we opted to treat this stent fracture by deploying a self-expanding 7-mm × 20-mm nitinol LifeStent NT (Edwards Lifesciences, Irvine, California) inside the fractured stent, delivered through an 8-F guiding catheter. The angiographic result was excellent, and fluoroscopy showed smooth flexion of the nitinol stent with respiration (Figure, c) Angiography 10 months later demonstrated persistent patency of the left renal artery and no further stent fracture. Because of the persistent respiratory movement of the kidney, and the enhanced flexion tolerance of nitinol versus stainless steel, we believe interventional management of renal artery stent fracture is better achieved with a self-expanding nitinol stent rather than another balloon-expandable stent. As another example of intraabdominal stent fracture, we would also like to report an unusual case of fracture of a balloon-expandable stent placed at the origin of the left common iliac artery. A 7-mm × 27-mm balloon-expandable Express stent (Boston Scientific) was placed at the origin of the left common iliac artery in a patient with a 4.6-cm abdominal aortic aneurysm. Three and a half years later, angiography showed increasing angulation of the aortoiliac junction (Figure, d) and resultant fracture of the iliac stent (Figure, e) associated with 60% restenosis between the two stent fragments. Because the patient was not symptomatic from the iliac stent fracture, treatment was not clinically indicated in this case. This unusual case illustrates that even the slow, incremental angulation associated with aortic aneurysms can result in sufficient metal fatigue to fracture a balloon-expandable stent at the origin of the common iliac artery. These cases highlight that the idea that intraabdominal balloon-expandable stents are free from the risk of fracture is a misconception. To restore patency while reducing the risk of recurrent stent fracture, treatment of these fractures might best be performed by deployment of a nitinol stent within the fractured stent.