Branched endovascular stent graft for thoracoabdominal aortic aneurysm repair

Abstracts

Apresentamos um caso de aneurisma da aorta toracoabdominal (AATA) tratado, exclusivamente, pela técnica endovascular, utilizando uma endoprótese ramificada e customizada. Paciente do sexo feminino, 68 anos de idade, tabagista, hipertensa, portadora de extenso AATA e múltiplas comorbidades que restringiam a indicação de cirurgia convencional. O aneurisma iniciava-se na aorta torácica descendente, estendendo-se até a aorta abdominal infra-renal, envolvendo as emergências das artérias viscerais, tronco celíaco, artérias mesentérica superior e renais. O AATA foi tratado pela técnica endovascular com implante de uma endoprótese ramificada. Essa endoprótese ramificada foi customizada com base nas características anatômicas da aorta e no posicionamento dos ramos viscerais, obtidos em angiotomografia, objetivando excluir o aneurisma, mantendo a perfusão das artérias viscerais. O procedimento foi realizado em centro cirúrgico, sob anestesia combinada, regional e geral, antecedido de drenagem liquórica e sob orientação fluoroscópica. O acesso para o implante do corpo principal da endoprótese ramificada e o controle radiológico foram realizados através das artérias femorais, previamente dissecadas. Através das ramificações da endoprótese, foram implantadas extensões secundárias, com stents revestidos, para as respectivas artérias viscerais, cujo acesso foi realizado via artéria axilar esquerda. O tempo total do procedimento foi de 14 horas, com 4 horas e 30 minutos de fluoroscopia, e foram utilizados 120 mL de contraste iodado. No pós-operatório, a paciente apresentou instabilidade hemodinâmica. Ecocardiograma transesofágico mostrou dissecção retrógrada da aorta torácica, tipo A, seguida de trombose espontânea da falsa luz. A tomografia de controle mostrou exclusão do AATA e perviedade das pontes para os ramos viscerais, sem vazamentos. A alta ocorreu no 13º dia de pós-operatório. O tratamento endovascular do AATA com endoprótese ramificada é factível. A melhora dos recursos técnicos e da qualidade dos materiais poderá ampliar a indicação desse procedimento como alternativa à cirurgia aberta.

Aneurisma toracoabdominal; endoprótese ramificada; artérias viscerais

CASE REPORT

Branched endovascular stent graft for thoracoabdominal aortic aneurysm repair

André Simi^I; Renato Ishii^I; Marcelo Ferreira^II; Anelise Santos^III; Antonio Carlos Simi^IV

^I

^IIHead, Integrated Service of Endovascular Techniques (SITE), Rio de Janeiro, RJ, Brazil

^IIIResident, Vascular and Endovascular Surgery, Hospital Santa Helena, São Paulo, SP, Brazil

^IVHead, Vascular and Endovascular Surgery Service, Hospital Santa Helena, São Paulo, SP, Brazil

^{Correspondence}

ABSTRACT

We report a case of branched stent graft system for endovascular repair of thoracoabdominal aortic aneurysm (TAAA).

A 68–year–old female patient, smoker, hypertensive, with a large TAAA and multiple comorbid conditions that restricted indication for conventional surgery. The aneurysm originated from the descending thoracic aorta, extending until the infrarenal abdominal aorta, involving the emergence of visceral arteries, celiac trunk, superior and renal mesenteric arteries. The TAAA was treated with the endovascular technique using a branched stent graft. This stent graft was customized based on the anatomical characteristics of the aorta and on the position of visceral branches, which were obtained by tomographic angiography, with the aim of excluding the aneurysm and maintaining perfusion of visceral arteries. The procedure was performed under regional and general anesthesia in the surgical room, preceded by cerebrospinal fluid drainage under fluoroscopic guidance. The femoral arteries, which were previously dissected, were used to implement the branched stent graft and for radiological control. Through the stent graft branches, secondary extensions were implanted, with covered stents, to the respective visceral arteries, which were approached via left axillary artery. Total operative time was 14 hours, 4 hours and 30 minutes of fluoroscopy time and 120 mL of iodinated contrast.

The patient became hemodynamically unstable after the surgery. Transesophageal echocardiogram showed a type A retrograde dissection of the thoracic aorta, followed by spontaneous thrombosis of the false lumen. Control tomography showed exclusion of the TAAA and patency of the bypasses to visceral branches, with no endoleaks. The patient was discharged on the 13^th postoperative day.

Branched endovascular stent graft for TAAA repair is feasible. Improvements in techniques and materials may increase the indication of branched stent graft as an alternative to open surgery.

Keywords: Thoracoabdominal aneurysm, branched stent graft, visceral arteries.

Introduction

Improvement in materials and techniques of endovascular treatment has promoted the successful repair of thoracoabdominal aortic aneurysms (TAAA) using a branched stent graft, which is implanted in the aorta and provides aneurysm exclusion and revascularization of visceral arteries: superior mesenteric artery, celiac trunk and renal arteries. It is a customized stent graft, whose design and construction are specific for each patient. The objective is to report our first case of TAAA treated with this new technology.

Case description

A 68–year–old, female patient, smoker, hypertensive, with congestive heart failure, chronic obstructive pulmonary disease and controlled renal failure was referred for TAAA treatment. Diagnosis was performed using a transesophageal echocardiogram and thoracic and abdominal tomography, after episodes of fall and loss of awareness. On physical examination, she presented hemodynamically compensated. There was palpable abdominal pulsatile mass, with presence of femoral and distal pulses and absence of murmurs. Tomographic angiography showed tortuous and atheromatous aorta in all its extension, with aneurysmal dilatation starting in the descending aorta and extending until the infrarenal segment, involving visceral arteries. Proximal neck of the aneurysm had a diameter of 3 cm in the descending aorta, and maximum diameter was 6.1 cm above the emergency of the celiac trunk, with extensive concentrically mural thrombus along the aneurysmal dilatation and thickening of 2.5 cm (Figure 1). Technical preparation to develop a branched stent graft – its dimensions and placement of branches for the respective bypasses – was determined by and based on the study and measurement of tomographic images. The branched stent graft was customized according to a specific project for the patient, and was shaped as a sandglass. From its medial segment, narrower than the ends, the branches go toward the visceral arteries (Figure 2). The surgical procedure to implant the device was performed at a surgical center, under fluoroscopic guidance, using a GE–OEC–9800 C–arm. Anesthesia was combined, regional and general, preceded by cerebrospinal fluid drainage, with continuous monitoring and systemic heparinization. Arterial approaches to perform the procedure were obtained through a bilateral, suprainguinal cross–sectional incision; the femoral arteries were dissected and 5F sheaths were introduced through dissection of the left axillary artery. Through the left femoral artery, a diagnostic 5F pig tail catheter was introduced and a panoramic aortography was performed (Figure 3). Next, a selective catheterization of a visceral, referential artery was performed to allow perfect placement of the stent graft. Introduction and implantation of the branched stent graft (Cook–Zenith), with a 22F caliber, was performed directly through the right common femoral artery, on a rigid Amplatz 0.035 guide wire and under fluoroscopic guidance. In the left femoral artery, a 12F sheath was introduced, and a fenestrated catheter was implanted to perform a provisory shunt for the stenosed left renal artery and prophylactic of renal ischemia. Next, we performed the opening of the branched stent graft and the respective proximal and distal adjustment with complacent balloon. Panoramic control angiography was performed (Figure 4). The previously dissected left axillary artery was used as an access for the selective catheterization of renal and superior mesenteric arteries and celiac trunk, and successive revascularization of these arteries was performed by implanting extensions through the branches. The first revascularized artery was the right renal artery. Through the corresponding branch we implanted an extension with an 8 x 40 mm Fluency covered stent and internal reinforcement with a 10 x 68 mm Wall Stent. After the temporary shunt was removed, the renal left artery was catheterized. Due to ostial stenosis, a 10 x 68 mm Wall Stent had to be initially placed in the left renal artery, followed by implantation of a 10 x 40 mm Fluency covered stent through the branch and internal reinforcement with a 10 x 42 mm Wall Stent. Next, the superior mesenteric artery was selectively catheterized and, through the corresponding branch, an extension with a 6 x 60 mm Fluency covered stent and internal reinforcement with an 8 x 40 mm Zilver Stent were implanted. Finally, we performed a catheterization of the celiac trunk, implantation of an extension with an 8 x 80 mm Fluency covered stent through the corresponding branch and internal reinforcement with a 10 x 60 mm Zilver Stent. Angiographic control showed adequate placement of the stent graft and its branches (Figure 5). The procedure was ended with arteriorrhaphy of the femoral and axillary arteries with 6–0 polypropylene and suture of skin incisions with nylon 5–0.

The procedure lasted 14 hours. Four hours and 30 minutes of fluoroscopy were necessary. The patient was given 120 mL of contrast material and two blood bags.

Postoperative (PO) care was performed at an intensive care unit. On the second day, there was worsening of hemodynamic standards. Chest radiograph showed mediastinal widening. The patient was maintained with noradrenaline infusion pump, orotracheal intubation and sedated. A new transesophageal echocardiogram showed that a segment of the thoracic aorta was dissected, proximal to the emergency of the left subclavian artery, extending until 3 cm of the valvar plane. The pericardium was normal. Hemoglobin was not altered, and creatinine was 1.5.

We chose to maintain the clinical treatment, with blood pressure control and enteral feeding. The patient presented positive hydroelectrolytic balance and normal renal function. On the third day, control transesophageal echocardiogram showed total thrombosis of the false lumen. The patient was maintained with noradrenaline and dobutamine. On the fourth day, dobutamine was suspended, with reduction in sedation, and the patient was extubated. On the fifth day, she presented episode of fever, leukocytosis and jaundice. She had normal SGOT and SGPT, increased FAA and gamma–glutamyl transpeptidase (GGT) and creatinine of 1.4. Cefepime 4 g/day, metronidazole 1.5 g/day and vancomicin 2 g/day were introduced. Control abdominal ultrasonography did not show pathological changes. The patient was maintained at an intensive care unit until the 10th PO day. At the ward, she presented progressive improvement in jaundice, good renal function and oral feeding. On the 12th PO day, metronidazole was suspended. On the 13th day, she was submitted to control tomographic angiography, which showed patency of the main stent graft and secondary branches, with no signs of endoleak (Figure 6). The patient was discharged in good conditions.

Discussion

The endovascular treatment of arterial lesions is not new. Dotter, in 1969, performed the first experiments of successful endovascular treatment in popliteal arteries of dogs.¹ But only in 1991 Parodi reported the first cases of successful endovascular treatment of infrarenal aortic aneurysm in humans.² The indication for this treatment modality has limitations and is related to the anatomical conditions of aneurysms,^3.4 but it has been increasingly more used due to enhancement and development of techniques, materials and equipment used to perform such procedures. The difficulties in using this technique are higher when the aneurysm is extensive, affecting the thoracic and abdominal aorta, with impairment of visceral and renal arteries, and are still a great challenge for surgeons.^5.6 TAAA are conventionally treated using throracotomies, with wide incisions in the abdomen and chest.⁷ With the aim of minimizing these procedures, a combined treatment, also called hybrid, has been suggested. This technique uses a tubular stent graft, allowing exclusion of the thoracic aortic aneurysm and of the segment that affects the origin of visceral arteries, and open abdominal access, allowing extra–anatomical bypasses for the respective visceral arteries.⁸ A recent publication showed good initial results using this technique.⁹ However, the most recent advancement in the TAAA treatment is performing its repair with an exclusively endovascular technique. To perform this procedure, a special, branched and customized stent graft is necessary according to the anatomical characteristics of the patient's aorta. The branched stent graft has a main body and secondary branches corresponding to the visceral arteries that need to be revascularized. The main advantage of this technique is allowing access and performing the procedure using small peripheral incisions. In addition, the entire procedure is performed without total interruption of the arterial flow in the aorta and in visceral branches.¹⁰ There are radiopaque markers at the upper and lower ends of the stent graft, along its anterior surface and branches, which serve as proximal, distal and axial guidance. The main body of the branched stent graft is narrower than its ends and does not totally reach the aortic wall, dilated and with thrombi, allowing the handling of respective branches. It is a new concept, but still represents limited experience.^11.12

Our experience concerning endovascular treatment of aortic aneurysms was sequential: endovascular treatment of infrarenal abdominal aortic aneurysms; treatment of thoracic aortic aneurysms and dissections; concomitant treatment of thoracic aortic aneurysm with tubular stent graft and of infrarenal abdominal aneurysm with bifurcated stent graft, without covering the aortic segment corresponding to the emergency of visceral arteries. Finally, we performed the endovascular treatment of this case, covering all the TAAA segment with the implantation of the branched stent graft main body and the respective secondary bypasses for the visceral arteries. The possibility of excluding the aneurysm safely, with no clamping and without totally compromising distal and visceral perfusion is undoubtedly an attractive and less invasive procedure. All instrumentation, insertion and release of the stent graft main body and the implantation of secondary bypasses to the aortic branches were performed under fluoroscopic guidance. Only arterial access was surgical, through small incisions at the inguinal and axillary regions, far from the target disease to be treated. Occasionally, some factors may compromise the perfect performance of this technique: excessive tortuosity of iliac arteries, which limit the freedom of the rotation and steering system of catheters; presence of thick and ostial thrombi; ostial stenoses of visceral arteries; and also, depending on aneurysm size, the space between the stent graft and the emergency of the visceral artery may create difficulty in inserting secondary bypasses and their branches. In our case, it was necessary to tunnel a thick parietal thrombus to provide access to the ostium of a visceral artery. It was also necessary to place an ostial stent in the stenosed left renal artery before implanting the branch.

The increasing number of indications for endovascular techniques is no longer restricted to surgeons' excitement.¹³ Collin¹⁴ predicted that the endovascular repair of aneurysms would fail, which was not confirmed. The obvious improvement in results is a consequence of new technologies. Progressive advances in the endovascular treatment of aneurysms in all segments of the aorta and increasing improvement in results justify indication of this technique for selected patients and for those with higher risk. The TAAA treatment using branched stent graft is not a routine treatment yet. As demonstrated in our case, treatment is individual and specific for each patient. It depends on a stent graft that is specially designed and customized for each patient, according to the anatomical data obtained from high–resolution tomography and tomographic angiography. The success of this procedure allows us to conclude that such technique is feasible and should be considered as an alternative in the treatment of TAAA.

Acknowledgement

To Dr. Timothy Chuter, for collaborating in the stent graft design and implantation.

References

Manuscript received October 24, 2006, accepted February 28, 2007.

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Publication Dates

• Publication in this collection
  19 July 2007
• Date of issue
  Mar 2007

History

• Received
  24 Oct 2006
• Accepted
  28 Feb 2007