Management of Iliac Stent Movement Complicating Peripheral Vascular Intervention: A Rescue Technique When Stent Deployment Malfu

ABSTRACT: Percutaneous transluminal peripheral angioplasty (PTA), with and without stenting, has become an effective, accepted, and safe approach for treating intermittent claudication and critical leg ischemia in selected patients. Percutaneous peripheral interventions are subject to complications that require unique solutions when compared to coronary interventions. We report a case of common iliac artery stenting complicated by stent migration and describe an approach to the management of this problem. Key words: percutaneous transluminal peripheral angioplasty Although percutaneous intervention for the treatment of peripheral vascular disease for symptomatic intermittent claudication is now considered a safe and common practice, such interventions may be compromised by stent deployment malfunction or malpositioning. We report a case of common iliac artery stenting complicated by stent migration and describe an approach to the management of this problem. Case Report: A 56-year-old woman with diabetes, hypertension and coronary artery disease presented with progressive shortness of breath and left lower extremity claudication. On physical examination, her blood pressure was 180/80 mmHg, heart rate was 70 beats per minute and respiratory rate was 18 breaths per minute. There were normal heart sounds, a soft S4 gallop, and no murmurs or jugular venous distention were appreciated. The lungs were clear to auscultation. The abdomen was unremarkable. There was no lower extremity edema. The resting ankle brachial index was 0.90 for the left leg and 0.95 for the right leg. An echocardiogram revealed depressed left ventricular systolic function with mild global hypokinesis, worse in the inferior and posterior left ventricular segments. Due to increasing symptoms of claudication and worsening left ventricular function, diagnostic coronary and peripheral angiography was performed. Coronary angiography revealed mild, diffuse, non-obstructive coronary artery disease. Left ventricular ejection fraction was 45% with mild mitral regurgitation. Medical therapy was recommended. Descending aortography demonstrated mild luminal irregularities and an ulcerative plaque distal to the origin of the left renal artery. There was a 60% stenosis in the left common iliac artery with a 20 mmHg mean systolic gradient (Figure 1). Percutaneous intervention was subsequently performed on the left common iliac lesion. After a 7 French (Fr) sheath was placed in the left common femoral artery, a 9 mm x 20 cm SMART stent was advanced and deployed across the iliac lesion over a 0.035´´ Glidewire. During deployment, the stent migrated cranially, only partially covering the stenosis. To cover the remainder of the lesion, a second stent was introduced. During positioning of the second stent, the initial stent was pushed further cranially into the distal aorta covering the ostium of the right common iliac artery (Figure 2). To address the problem of the stent covering the non-obstructed iliac ostium, a decision was made to reconstruct the distal aorta and ostia of the iliac arteries. A second 7 Fr sheath was placed in the right common femoral artery. Another 0.035´´ Glidewire was then passed laterally to the deployed stent. The positioning of this Glidewire lateral to the first stent in the distal aorta was confirmed by intravascular ultrasound followed by balloon inflation (Figures 3 and 4). Using a simultaneous stent deployment technique, two SMART stents (12 mm x 6 cm and 12 mm x 4 cm) were deployed in the left and right common iliac arteries, respectively, with the proximal portions of the stents extending into the distal aorta. The stents were then dilated using a 10 mm x 4 cm Powerflex balloon achieving good angiographic results with no residual narrowing or pressure gradient across either stent (Figures 5 and 6). After the procedure, the patient received Lovenox for 72 hours and Plavix plus aspirin for 4 weeks. Clinical follow-up at 4 weeks revealed improvement in claudication and good distal pulses. Discussion. Percutaneous transluminal peripheral angioplasty (PTA), with and without stenting, has become an effective, accepted and safe approach for treating intermittent claudication and critical leg ischemia in selected patients, thanks to the pioneering work of Charles Dotter, Andreas Gruentzig, Eberhard Zeitler, and others in the development of peripheral and coronary angioplasty.^1–3 While generally safe and effective procedures, percutaneous peripheral interventions are subject to complications that require unique solutions when compared to coronary interventions. Major complications of peripheral vascular angioplasty and stenting include vessel dissection, acute vessel occlusion, distal embolization, arterial rupture, limb loss and death, with an incidence of 5.4% for major complications and a 30-day mortality rate of 1%.^4–6 Arterial rupture and arterial perforation occur in 0.2% of patients, and can frequently be managed by placement of a covered stent.^4–6 Minor complications such as puncture site hematoma or false aneurysm are reported in 4–5% of patients.^4–6 Few studies report stent migration, malposition or stent loss as a complication. This case describes a unique, but probably not uncommon, scenario wherein a short, self-expanding stent abruptly jumped cranially from the common iliac artery into the distal aorta. Options for management of this complication included emergent vascular surgery, observation, stent retrieval or aortoiliac bifurcation reconstruction.^7,8 The use of intravascular ultrasound to guide distal aortic reconstruction assisted in verifying correct guidewire positioning outside the left iliac stent and avoiding emergent vascular surgery. The technique of aortoiliac bifurcation reconstruction has been known for many years and is the method of choice for percutaneous intervention when complex plaque involves the distal aorta and ostia of the iliac arteries.^8–12 Scheinert et al.¹² report initial and follow-up results in primary stent aorto-bifurcation reconstruction in 48 patients with > 85% bilateral narrowing of the common iliac arteries. Success was achieved in all patients with American Heart Association criteria for clinical improvement of +2 and +3 achieved in 41 and 7 patients, respectively. Primary patency at 24 months was 87%. These results have been replicated by others. The technical aspects leading to optimal results emphasize correct sizing of balloons and stents for the normal distal reference segment. Calcified lesions require full stent apposition after larger balloon inflations. In some cases, two simultaneously inflated, smaller diameter balloons may be needed. However, over-dilation to prevent aortoiliac rupture should be avoided. Stent length and position should be carefully chosen to cover the entire lesion, especially critical for ostial stenoses. Self-expanding stents, which shorten excessively, are not optimal. Indications for percutaneous iliac artery angioplasty and stenting focus principally on significant symptoms or limb jeopardy. Based on angiographic demonstration of aortoiliac, femoral and lower extremity anatomy, the Society of Cardiovascular and Interventional Radiology (SCIVR) has established a lesion grading system for percutaneous transluminal angioplasty (PTA) (Table 1). Our patient had a SCIVR category I lesion with symptoms. Direct stenting the iliac arteries was elected ad hoc, an increasingly common practice. Some operators believe that stent implantation following iliac artery angioplasty is only required for lesions with > 30% residual stenosis or > 10 mm residual mean gradient across the lesion after PTA.^15,16 However, stenting of iliac lesions is associated with equal or better outcomes than balloon angioplasty alone.¹⁶ Unanticipated stent advancement with self-expanding stents is not uncommon. Unfortunately, most of these stents, once deployed, are almost impossible to retrieve. A useful lesson from this case is for interventionalists to consider using balloon-expandable, rather than self-expandable stents when there is concern about precise stent positioning or potential stent migration, especially adjacent to vulnerable areas, such as the contralateral iliac ostia of the distal aorta. Operators may also want to consider using slightly longer stents for deployment in such regions.

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