Carlos A.C. Pedra,* MD, Carlo B. Pilla, MD, Sérgio L.N. Braga, MD, César A. Esteves, MD, and Valmir F. Fontes, MD

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1 Catheterization and Cardiovascular Interventions 56: (2002) Management of a Large Pseudoaneurysm Secondary to Balloon Dilation for Native Coarctation of the Aorta With Coil Occlusion After Stent Implantation in a Child Carlos A.C. Pedra,* MD, Carlo B. Pilla, MD, Sérgio L.N. Braga, MD, César A. Esteves, MD, and Valmir F. Fontes, MD We report a case of a 9-year-old girl status post balloon dilation for native coarctation of the aorta who had a large aortic pseudoaneurysm 1 year after the initial procedure. The aneurysm was occluded with multiple coils after stent implantation to the aorta. The technique and possible advantages of this novel approach are discussed. Cathet Cardiovasc Intervent 2002;56: Wiley-Liss, Inc. Key words: coarctation of aorta; aneurysm; stents; coils; interventional cardiology INTRODUCTION Balloon dilation of native coarctation of aorta has been employed safely and effectively in selected patients with good results during follow-up [1 4]. However, pseudoaneurysm formation at the site of dilation occurs in about 2% 8% of patients [2 4]. Although the majority of these aneurysms remain stable, it occasionally may increase in size during follow-up, raising concerns in regard to potential rupture, massive bleeding, and death [3 5]. We report a case of aneurysm formation after balloon dilation of native coarctation of aorta treated successfully with coil occlusion after stent implantation. CASE REPORT An 8-year-old girl, weighing 22 kg, with clinical and echocardiographic diagnosis of coarctation of aorta was referred to our institution for possible percutaneous treatment in November Under general anesthesia, left heart catheterization was carried out, which demonstrated the following pressures: ascending aorta, 130/75; descending aorta, 90/68. An aortogram showed a discrete and symmetric coarctation in the proximal descending thoracic aorta at the level of the ductal ligament, with normal sized isthmus (Fig. 1). The narrowest site measured 3 mm, the isthmus 12 mm, and the descending aorta at the level of the diaphragm 12 mm. She underwent balloon dilation according to previous published protocols and technique, with hand inflation of the balloons [1,2]. A 10 mm 2 cm balloon catheter was used initially with suboptimal result due to the presence of a residual gradient of about mm Hg. A 12 mm 2 cm catheter balloon was subsequently employed with abolition of the residual gradient. However, repeat aortogram demonstrated a discrete line of dissection on the postero-lateral aspect of the aorta at the site of dilation with some degree of external bulging (Fig. 1). She had an uneventful recovery and was discharged home on the following day on propranolol (1 mg/kg/day). She did well with normal blood pressure and showed no clinical signs of recoarctation during follow-up. She was brought back after a year for repeat catheterization and angiograms to assess the late results. Although no gradient was detected across the previous coarctation site, an aortic angiogram showed a large aneurysm measuring 14 mm 10 mm at the same site of the initial dissection (Fig. 2). The isthmus measured 14 mm and the descending aorta at the level of the diaphragm 15 mm. Due to its size and significant progression over a year, we decided to manage the aneurysm with coil occlusion after stent implantation. Informed consent was obtained and the patient was brought back 2 weeks later for a third catheterization under general anesthesia. At that time, her weight was 26 kg. A 7 Fr Berman angiographic catheter (Arrow International, Reading, PA) was placed in the ascending aorta in an antegrade fashion through a transeptal approach for control angiograms and pressure recordings [4]. Two 5 Fr sheaths were placed in both Instituto Dante Pazzanese de Cardiologia, São Paulo, Brazil *Correspondence to: Dr. Carlos A.C. Pedra, Instituto Dante Pazzanese de Cardiologia, Av Dr Dante Pazzanese 500, CEP , São Paulo, SP, Brazil. cacpedra@uol.com.br Received 15 August 2001; Revision accepted 16 January 2002 DOI /ccd Published online in Wiley InterScience ( Wiley-Liss, Inc.

2 Coil Occlusion of Aortic Aneurysm in Child 263 Fig. 1. Aortic angiograms in shallow left anterior oblique views. Left: Discrete and symmetric coarctation with normal sized isthmus. A remnant of the ductal ampulla is seen. Right: After dilation with a 12 mm 2 cm balloon, a discrete line of dissection with external bulging is seen at the left-posterior aspect of the aortic wall. Fig. 2. Aortic angiograms in shallow left anterior oblique views. Left: A large pseudoaneurysm at the previous site of dissection and bulging is seen 1 year after dilation. There is no residual narrowing. Right: A satisfactory stent position with minimal straddling of left subclavian artery after deployment is demonstrated. The aneurysm is still opacified. femoral arteries and the patient received 150 IU/kg of heparin. The coarctation area was crossed with a right coronary Judkins catheter (Cordis, Johnson and Johnson, Miami, FL) with the aid of a hydrophilic guidewire (Road-Runner, Cook, Bloomington, IN). A extrastiff guidewire (Amplatz, Cook) was positioned distally in the right subclavian artery through the Judkins catheter. Over this wire, a straight 9 Fr long sheath with dilator (Cook) was advanced across the lesion from the right groin. After removal of the dilator, a CP stent (8 zig, 39 cm; Numed, Cornwall, ON, Canada) mounted on a 14 mm 6 mm Tyshak II (Numed) catheter balloon was inserted into the sheath and advanced to the desired location. Repeat test injections through the Berman cath-

3 264 Pedra et al. Fig. 3. Aortic angiograms in shallow left anterior oblique views. Left: The right coronary Judkins catheter was positioned between the stent struts to deliver the coils, which are seen inside the aneurysm. The catheter balloon was left within the stent. Right: Faint opacification of the superior portion of the aneurysm is still seen immediately after the procedure. eter confirmed that the stent was covering the aneurysm completely. After retraction of the sheath, the stent was expanded with a peak inflation pressure of 2 atm with minimal straddling of the left subclavian artery. The distal end was subsequently flared using a 16 mm 3cm Tyshak II catheter balloon (Numed). An angiogram confirmed the satisfactory position of the intravascular implant. However, as it had been anticipated, significant opacification of the aneurysm was still seen through the stent struts (Fig. 2). The 16 mm Tyshak catheter balloon was slightly pulled back and left in the descending aorta within the stent. Through the contralateral femoral artery, a 5 Fr right coronary artery Judkins catheter was advanced with the aid of a hydrophilic guidewire and positioned inside the superior aspect of the aneurysm through the stent struts (Fig. 3). Through this catheter, five Gianturco coils (Cook) were sequentially delivered inside the aneurysm: ; ; Repeat aortogram demonstrated faint opacification of the aneurysm with almost complete obliteration of flow (Fig. 3). Fluoroscopy time was 42 min and procedure time was 3.5 hr. After removal of catheters and sheaths, hemostasis was achieved by manual compression. The patient was extubated in the catheterization laboratory and transferred to the intensive care unit. She had an uneventful recovery and was discharged home on the following day with normal blood pressure and excellent distal pulses. An echocardiogram demonstrated no gradient across the stent. The pack of coils could be seen in the posterior aspect of the aorta and no flow through the stent struts could be detected by color flow mapping. Repeat catheterization performed 6 months after stent and coil implantation demonstrated complete occlusion of the aneurysm (Fig. 4). There was no intimal proliferation within the stent, including the area adjacent to the coils. No gradient was detected across the left subclavian artery, ascending and descending aorta. Repeat catheterization for possible stent redilation is anticipated in 4 6 years after puberty because of the expected increase in growth velocity in this period. DISCUSSION Balloon angioplasty acts by tearing the vessel wall with disruption of the intima and part of the media. After the healing process takes place in the vessel, its wall is restored and its lumen enlarged [5]. Pseudoaneurysm formation is a well-known complication after balloon dilation of native coarctation of aorta. Although there is no consensus, it is generally defined as a bulge in the aortic wall, whose diameter is 1.5 times the aorta at the level of the diaphragm [3]. It is probably caused by a complete transmedial tear that may occur after dilation, resulting in loss and disarray of supporting smooth muscle cells causing a weakening in the vessel wall [5]. Technical factors, such as the use of oversized balloons

4 Coil Occlusion of Aortic Aneurysm in Child 265 Fig. 4. Aortic angiogram in shallow left anterior oblique views in the repeat catheterization performed 6 months later. No flow in the aneurysm was seen. with overdistension of the vessel and longer inflation times, may contribute to this event in the acute setting [3 5]. Although neither of these factors was present in our case, a line of dissection was clearly seen in the immediate postdilation angiogram. The tear probably extended to the adventitia creating the anatomic substrate for the aneurysm formation. Whether this happened immediately after the procedure or during follow-up remains speculative. Histologic findings similar to cystic medial necrosis, commonly found near the area of coarctation, may be an additional risk factor for aneurysm formation [6]. It is generally thought that these sacular dilatations have a benign natural history, remaining stable. Progression at intermediate follow-up is uncommon, although their long-term fate remains a concern [5]. There are no definite guidelines regarding the management of this complication. Most investigators advocate a more conservative approach, with clinical follow-up and the use of serial noninvasive studies such as MRI to assess the aneurysm size [3,4]. When there is rapid progression of the aneurysm reaching significant dimensions, as it did occur in the case reported here, some kind of intervention may be required. Surgical repair may theoretically carry a higher risk because of the involution of collaterals seen after dilation and the need of aortic clamping. Covered endovascular stents have been used to treat aortic and peripheral artery aneurysms in the adult population with good results [7]. The application of this technique in children is limited because of the need of large sheaths required for implantation, usually performed through surgical ateriotomies. However, treatment of an abdominal aortic pseudoaneurysm with a homemade covered stent implanted through a 14 Fr sheath in an adolescent with neurofibromatosis has been reported [8]. Since covered stent technology was not available in our institution, we decide to implant a standard stent followed by coil thrombo-obliteration of the aneurysm through its struts. Although the super-thin Tyshak II catheter balloon is not generally indicated for stent deployment due to increased risk of balloon rupture by the stents struts, it was selected in this case because of its low profile allowing the use of an acceptable size sheath for the patient s weight (9 Fr, 26 kg). In addition, balloon puncture was unlikely because of the straight course of the lesion and the use of the CP stent with rounded and less abrasive edges. Although the maximal burst pressure is 3 atm for the Tyshak II catheter balloon, high pressures were not required in our patient because of the compliant nature of the vessel wall. As there was not any stiff lesion to be dilated, the balloon was used just to appose the stent against the aortic wall. The stent was dilated to 14 mm, matching exactly the size of the isthmus. We speculate that the use of a larger balloon could have stretched the aortic wall, increasing the size of the aneurysm. Although we do not routinely flare the distal end of the stent in our adolescents and adults with coarctation, we decided to do that in this case to provide more stability to the intravascular implant for further manipulation. The selection of a CP stent rather than a Palmaz stent was not only because of its rounded edges. This choice was also based on the hypothesis that the space between the struts would be larger in the former than in the latter after dilation to only 14 mm. A too-small space between the struts might have precluded the passage of the 5 Fr right coronary Judkins catheter for coil delivery. We acknowledge that the use of detachable coils could have been safer, minimizing the risk of inadvertent migration. Nevertheless, the use of Gianturco coils proved to be feasible, safe, and effective to obliterate the aneurysm. The first delivered coil was chosen to be the largest one, working as a scaffold for the remainder. An 8 mm diameter was selected because the maximal dimension of the space between the struts was about 8 mm, measured vertically. Due to the possibility of aneurysm rupture during catheter and guidewire manipulation for coil implantation, this procedure was done through the contralateral artery, leaving the catheter balloon (used for flaring) nearby in case it was temporarily needed to seal off any leakage before urgent surgical intervention was carried out.

5 266 Pedra et al. The goal of inducing aneurysmal thrombosis by coil delivery with presumed stabilization of the vascular sac was accomplished in this case. This may prove to be a better option compared to the use of endovascular grafts since perigraft channels can leak into the aneurysmal sac, leading to continuing expansion and eventual rupture [9]. Due to the child s somatic growth, it is likely that the stent needs to be dilated at some point during follow-up, committing this patient to further catheterizations. However, experimental and clinical data show the feasibility, safety, and efficacy of stent redilation [10,11]. Although we are optimistic about the late results of this approach to manage aortic aneurysms in children, further experience and longer follow-up are required. ACKNOWLEDGMENTS We thank Drs. Lee Benson, Charles E. Mullins, and Andrew Redington for their valuable comments and suggestions. REFERENCES 1. Tynan M, Finley JP, Fontes V, Hess J, Kan J. Balloon angioplasty for the treatment of native coarctation: results of Valvuloplasty and Angioplasty of Congenital Anomalies registry. Am J Cardiol 1990;65: Fontes VF, Esteves CA, Braga SLN, da Silva MV, E Silva MA, Sousa JE, de Souza JA. It is valid to dilate native aortic coarctation with a balloon catheter. Int J Cardiol 1990;27: Ovaert C, Benson LN, Nykanen D, Freedom RM. Transcatheter treatment of coarctation of the aorta: a review. Pediatr Cardiol 1998;19: Fletcher SE, Nihill MR, Grifka RG, O Laughlin MP, Mullins CE. Balloon angioplasty of native coarctation of the aorta: midterm follow-up and prognostic factors. J Am Coll Cardiol 1995;25: Moore JW, Lock JE. Catheter intervention: balloon angioplasty experimental studies, technology and methodology. In: Lock JE, Keane JF, Perry SB, editors. Diagnostic and interventional catheterization in congenital heart disease, 2nd ed. Boston: Kluwer Academic Publishers; p Isner JM, Donaldson RF, Fulton D, Bhan I, Payne DD, Cleveland RJ. Cystic medial necrosis in coarctation of the aorta: a potential factor contributing to adverse consequences observed after percutaneous balloon angioplasty of coarctation sites. Circulation 1987; 75: Chaikof EL, Matsumura JS. Endovascular repair of abdominal aortic aneurysm: problems and progress. Semin Vasc Surg 1999; 12: Khan MS, Moore JW. Treatment of abdominal aortic pseudoaneurysm with covered stents in a pediatric patient. Cathet Cardiovasc Intervent 2000;50: Schurink GW, Aarts NJ, van Baalen JM, Chuter TA, Schultze Kool LJ, van Bocke JH. Late endoleak after endovascular therapy for abdominal aortic aneurysm. Eur J Endovasc Surg 1999;17: Morrow WR, Palmaz JC, Tio FO, Ehler WJ, VanDellen AF, Mullins CE. Re-expansion of balloon-expandable stents after growth. J Am Coll Cardiol 1993;22: Suarez de Lezo J, Pan M, Romero M, Medina A, Segura J, Lafuente M, Pavlovic D, Hernandez E, Melian F, Espada J. Immediate and follow-up findings after stent treatment for severe coarctation of aorta. Am J Cardiol 1999;83: