CASE REPORTS

Self-fabricated Covered Stent to Exclude an Aortic Aneurysm after Balloon Angioplasty for Post-surgical Recoarctation

Ralf Holzer, MD, Karen Concilio, PA, Ziyad M. Hijazi, MD
Ralf Holzer, MD, Karen Concilio, PA, Ziyad M. Hijazi, MD
The management of coarctation of the aorta beyond the immediate neonatal period has long been the focus of much controversy. Development of aortic aneurysms, with their inherent risk of spontaneous rupture and death,1,2 is not infrequently observed in this condition, with an incidence of about 9% after surgical correction — most frequently after patch angioplasty2 — and 5% after balloon angioplasty.3,4 The risk of aneurysm formation in untreated, native coarctation has been estimated to be 20% by the end of the third decade of life.5 Historically, this complication has been managed surgically but, endoluminal repair via exclusion of these aneurysms has recently been established as an attractive, less invasive management option.6–11 Case report. We report the case of a 13-year-old boy who was born with coarctation of the aorta and a small perimembranous ventricular septal defect. He underwent surgical repair of the coarctation using resection and end-to-end anastomosis at day 7 of life. At the age of 5 years, he underwent surgical resection of the membranous subaortic membrane, at which time the small ventricular septal defect was also closed by direct suture. He did well until the age of 10 years, when clinical evaluation demonstrated systemic hypertension with an arm-leg cuff blood pressure difference of 17 mmHg, and echocardiographic suggestion of recoarctation, with peak descending aortic Doppler velocities of 3.1 m/s. Hemodynamic evaluation in the cardiac catheterization laboratory demonstrated the presence of a 20 mmHg peak systolic gradient across the descending aorta, and angiography showed evidence of localized recoarctation. The narrowest diameter was 9 mm, the isthmus was 16 mm, and the descending aorta was 21 mm. Balloon angioplasty was performed using a 15 mm x 3 cm Z-Med II balloon (NuMED Corporation, Hopkinton, New York) without any residual gradient and improved angiographic appearance, with a small intimal flap at the site of angioplasty. Magnetic resonance imaging 6 months later revealed no evidence of aneurysm formation, with only minimal residual narrowing distal to the origin of the left subclavian artery. Clinically, there was no residual arm-leg cuff blood pressure gradient. He was evaluated again 2 years later, at which time he was slightly hypertensive (BP in right arm 137/68 mmHg), with an arm-leg cuff blood pressure gradient of about 27 mmHg, with peak descending aortic velocity on Doppler echocardiography of 3.0 m/sec. Cardiac catheterization demonstrated an 11 mmHg peak systolic gradient across the descending aorta and angiography revealed the presence of a 9.1 mm saccular aneurysm directly adjacent to the origin of the left subclavian artery (Figure 1), with only very trivial residual narrowing at the isthmus. Exclusion of the aneurysm using a covered stent was considered; however, the adjacent origin of the left subclavian artery would have been compromised by the covered stent, with potential left-arm ischemia. Two months later, the patient underwent uncomplicated surgical insertion of a 6 mm PTFE jump graft from the left common carotid artery to the left subclavian artery. One month after that, he was taken back to the cardiac catheterization laboratory for insertion of a covered stent at the aneurysm site. The aortic isthmus measured 14.5 mm, the descending aorta 16.2 mm, and the aneurysm had a maximum diameter of 18.6 mm. The previously inserted graft from left the carotid to the left subclavian artery was patent (Figure 1). A 6 mm diameter x 39 mm long thin PFTE shunt (WL Gore Associates, Flagstaff, Arizona) was cut, and this was mounted on a PG-3910 Genesis stent (Cordis Corporation, Miami Lakes, Florida) and was sewn to the stent ends in the catheterization laboratory using 6.0 Gore-Tex suture material (WL Gore Associates, Flagstaff, Arizona). Next, the entire assembly (covered stent) was mounted on a BiB balloon catheter (Balloon-in-Balloon catheter, Numed Corporation, Hopkinton, New York), with outer balloon dimensions of 16 mm x 4 cm, and the inner balloon dimensions of 8 mm x 3 cm. This was then front-loaded into an 11 Fr Mullins sheath via a 13 Fr sheath. The stent was then deployed in the appropriate position during right ventricle over-drive pacing to prevent the stent from moving during balloon inflation. Repeat pressure measurement and angiography post-deployment demonstrated no residual gradient and excellent stent position, with complete exclusion of the aneurysm without residual leak, and no residual coarctation (Figure 1). The fluoroscopy time for this procedure was 8.7 minutes and the procedure time was 103 minutes. The patient was discharged home the following day on 81 mg aspirin. At one-month follow-up, the patient had normal blood pressure, with no gradient between the arm and leg by cuff pressure measurement. Doppler evaluation revealed a velocity of 2 m/sec in the descending thoracic aorta. Discussion. The management of descending thoracic aortic aneurysms after repair of coarctation is associated with increased morbidity and mortality. Knyshov and colleagues reported re-operation for aortic aneurysms after surgical repair of coarctation to be associated with a perioperative mortality rate of 13.8%. However, all 18 patients who did not undergo repair of the aneurysm died between 7 and 18 years after the initial surgical procedure.1 In 2002, Kodolitsch and colleagues reported a 36% mortality rate if aneurysms after surgical repair of coarctation were left untreated, which well exceeded an early mortality rate of 4% after surgical repair of such aneurysms. Based on this premise, a percutaneous approach using covered stent grafts for exclusion of these aneurysms may offer an attractive alternative to surgical management. In 1999, Gunn and colleagues reported on the successful use of an AneuRx self-expanding, nitinol mesh stent (Medtronic, Watford, United Kingdom), covered with a PTFE membrane, in a 23-year-old gentleman with native coarctation and an associated aneurysm.12 Larger recent series, reporting on the use of endovascular stent grafts in patients with a variety of aortic pathology, reported an early mortality rate of 8–8.5%.11,13 However, these series included a less coherent and potentially more difficult to manage group of patients, including emergency procedures in patients with acute dissection, aortic transsection, traumatic dissection, and ruptured degenerative aneurysms. In contrast, Bell and colleagues reported on endoluminal repair of aneurysms associated with coarctation in 5 patients with zero mortality. The stent grafts used were the Excluder (WL Gore and Associates, Livingstone, United Kingdom) and the Zenith (Cook Europe, Bjaevershov, Denmark), which required large 22–24 Fr delivery sheaths. These results have been confirmed by Ince and colleagues who reported a zero percent early mortality rate when treating 6 consecutive patients with descending aortic aneurysms after previous patch aortoplasty for coarctation, using the Talent stent graft (Medtronic, Sunnyvale, California).6 Forbes and colleagues described the successful use of a polytetrafluorethylene (PTFE)-covered Cheatham-Platinum stent (Numed, Hopkington, New Jersey), dilated to 12 mm in the treatment of a 14-year-old girl with an aneurysm and recoarctation after previous balloon angioplasty of native coarctation,8 using a 13 Fr sheath. The same type of stent was used by Sadiq and colleagues in a 19-year-old girl with native coarctation to simultaneously exclude an associated patent arterial duct.7 While the covered Cheatham-Platinum stent may be specifically useful in the pediatric population, the availability of adequately-sized covered stents in the United States is limited, pending the completion of appropriate trials and United States Food and Drug Administration (FDA) approval. In our patient, we demonstrated that the creation of a covered stent during an interventional procedure is feasible, using genuinely available stents and prosthetic materials. However, care must be taken not to undersize the delivery sheath to avoid dislodgement of the Gore-Tex membrane. A front-loading approach is generally preferable for better control over the assembled covered stent. The maximum size of sheath used in this 13-year-old patient was 13 Fr, which was well-tolerated without any femoral vascular complications. In the future, with growth of the patient, this stent graft would be amenable for balloon re-expansion to accommodate the expanding size of the aorta. In our patient, treatment options were carefully considered. After two previous cardiac surgical procedures, a less invasive approach was the preferred option for the patient and his family, especially in light of the risk of considerable surgical morbidity and mortality. Immediate endoluminal repair was considered to be associated with a risk of left arm ischemia or neurological deficit, thus, an initial PTFE jump graft was implanted from the left common carotid to the left subclavian artery in a minimally invasive vascular surgical procedure. Hausegger and colleagues reported on 3 patients in whom endoluminal repair of descending aortic aneurysms or dissections was undertaken, intentionally implanting the stent grafts over the ostium of the left subclavian artery resulting in no neurological deficits or left arm ischemia.10 While this documents that this approach is feasible, we felt that our approach added an additional safety margin to the procedure, with only a minimal added procedural risk through implantation of the carotid jump graft. We conclude that endoluminal repair of aneurysms associated with previous surgical or percutaneous interventions for coarctation of the aorta should be the preferred treatment option. Our case documents that “on-the-table” creation of a covered stent is feasible and provides excellent results. Acknowledgment. The authors wish to thank Dr. James McKinsey who performed the graft between the carotid and the subclavian arteries, Dr. Qi-Ling Cao for reproduction of figures and Dr. David Waight for patient referral.
References
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