Successful Exclusion of Descending Thoracic Aortic Pseudoaneurysm by Endovascular Stent-Graft Placement<br />

Thoracic aortic aneurysm continues to be a life-threatening problem because of associated comorbid conditions and high morbidity and mortality associated with conventional open repair.1 Despite the remarkable improvements in treatment as a result of technical advances and improved prosthetic grafts, the operative mortality remains high.2 In addition to morbidity related to thoracotomy and cardiopulmonary bypass, open surgical resections and repairs are associated with bleeding, paraplegia, strokes, renal insufficiency and potential need for prolonged ventilatory support in the postoperative period.3 Successful use of endoluminal stents in abdominal aortic aneurysms4–5 has prompted investigators to assess the feasibility of this technique in thoracic aortic aneurysm repair.6–7 Initial experience has proven the feasibility of this technique and the results seem promising, especially in high-risk patients.8–9 We report a case of successful stent endograft repair for descending thoracic aorta pseudo-aneurysm rupturing into a retroperitoneal malignant fibrous histiocytoma tumor mass. To the best of our knowledge, endovascular stenting for contained rupture in descending thoracic aorta has not been reported. Case Report. A 62-year-old woman presented to the emergency room with a two-day history of non-exertional chest pain, sharp back pain and shortness of breath. There was no associated history of nausea, vomiting, diaphoresis or fever. Her past medical history was significant for malignant fibrous histiocytoma, hypertension and pulmonary thromboembolism secondary to deep vein thrombosis. Her medications included acetaminophen, diltiazem, and warfarin. She was receiving radiation therapy and chemotherapy for malignant fibrous histiocytoma. Physical examination revealed decreased air entry in left lower chest on auscultation. A cardiovascular, abdominal and neurological assessment was normal. There was no evidence of deep vein thrombosis in the lower extremities. Vital parameters were: pulse 122 bpm, regular, all peripheral pulses were well felt; blood pressure 138/78 mm Hg; respiratory rate 18/minute; temperature 98.2ºF and oxygen saturation of 97% on 2 L of oxygen supplementation by mask. Chest X-ray showed left lower lobe consolidation with pleural effusion. Spiral CT scan of chest was negative for pulmonary thromboembolism, but revealed aortic wall disruption on the lateral aspect of the descending thoracic aorta suggestive of contained aortic rupture or pseudoaneurysm formation (Figure 1A & 1B). The ECG and routine biochemistries were within normal limits. The patient was taken for percutaneous endograft stent placement after informed consent. The procedure was performed under general anesthesia. The femoral artery was exposed by primary incision in the groin and was cannulated using the Seldinger technique with an 8 French (Fr) introducer sheath after exposing the femoral artery. A 5 Fr pigtail catheter was placed in position at the level of descending thoracic aorta. A marking ruler was placed and arteriogram was then performed with Isovue-370, which identified the pseudoaneurysm (Figure 2A) and later used as a roadmap for endovascular stent deployment. The femoral artery was serially dilated and 8 Fr introducer was exchanged with 22 Fr sheath under direct vision maintaining adequate hemostasis with vessel loop. The 21 Fr device was placed in the descending thoracic aorta and positioned under fluoroscopy to cover the pseudoaneurysm proximal to the leak and then a 28 mm long AneuRx cuff was deployed. The device sheath was removed after deployment of the stent with direct control of bleeding at the groin. Arteriogram was performed following the procedure, which demonstrated no leakage in the descending thoracic aorta (Figure 2B). The right femoral artery was directly repaired under vision with interrupted 5–0 prolene sutures and subsequently the groin incision was closed with deep layer of 2–0 Dexon followed by subcuticular 3–0 Dexon suture. The patient was systemically heparinized with 5,000 units prior to dilatation and stent placement. There was no complication during and after the procedure. Contrast CT scans of chest at 7 weeks following procedure (Figure 3), revealed stable stent graft without any evidence of migration or leak. Pleural effusion was tapped subsequently and fluid was examined for malignant cells. In addition, an IVC green field filter was placed during hospitalization to prevent pulmonary embolism in view of recurrent history of deep vein thrombosis. Discussion. The high mortality rate associated with conventional surgical approach to thoracic aortic aneurysms in presence of co-morbid conditions has introduced use of endovascular stents. The goal is to provide durable exclusion of the aneurysm sac, while minimizing the morbidity and mortality of procedure. Mitchell and colleagues have substantiated the safety and effectiveness of stent graft repair of pseudo aneurysms.6 Three major factors need to be considered before endoluminal stent graft procedure. These include location and morphology of aneurysm, sufficient size of distal vascular access and limited tortuosity of abdominal and thoracic aorta. We performed contrast CT scan of the chest and aortogram to delineates the size of pseudoaneurysm, its relation to celiac axis and the proximal and distal landing zones before endograft stent placement. Despite the theoretical advantages offered by an intraluminal approach, the treatment of aneurysms must be viewed in context of the patient’s life expectancy and risk of intervention. In our patient, it was mandatory to intervene in view of rupture of the pseudoaneurysm into the tumor mass. Open surgery was not feasible because of her inoperable thoracic malignancy, which was eroding into descending thoracic aorta. Access problems, early delivery or device failure, and graft related issues are the main concern with endograft stenting. Fixation of the endograft to the delivery device provides added accuracy during deployment, because the downward force applied by the column of blood in the thoracic aorta is countered by the secure positioning of the delivered device. Minor adjustments can be made after deployment of the main body of the graft to prevent distal migration of the stent. Endograft stenting of thoracic aorta is also useful in setting of acute traumatic rupture of thoracic aorta. Thompson et al had reported five cases of traumatic thoracic aorta rupture, which were successfully managed with endograft stent delivered percutaneously.10 Few isolated cases of endograft stent for thoracic aorta had been reported for Aortoesophageal fistula and traumatic false aneurysm.11–12 The patient stayed free of endoleak, stent migration, renal insufficiency and neurological complications during four months of follow up. The endovascular approach is feasible for descending thoracic aorta pseudoaneurysm and may offer the best means of therapy in high-risk patients with co-morbid conditions.

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