Asian Cardiovasc Thorac Ann 2004;12:99-102
© 2004 Asia Publishing EXchange Ltd
Endovascular Stent-Graft Repair of Aortic Dissection
Xiao-Xi Li, MD,
Sheng-Ming Wang, MD,
Wei Chen, MD1,
Wen-Quan Zhuang, MD1,
Zhuan-Hong Wu, MD,
Guang-Qi Chang, MD,
Song-Qi Li, MD,
Jian-Yong Yang, MD,
Yong-Jie Lin, MD
Department of Surgery
1 Department of Intervention Radiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, People Republic of China
For reprint information contact: Xiao-Xi Li, MD Tel: 86 20 8775 5766 Fax: 86 20 8775 0632 Email: lix2{at}21cn.com Department of Surgery, First Affiliated Hospital, Sun Yat-sen University, 58 Zhongshan Road II, Guangzhou 510080, People’s Republic of China.
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ABSTRACT
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Between October 2000 and January 2002, 9 consecutive male patients with subacute or chronic aortic dissection underwent stent-graft placement. The indication for surgery was continuous pain or aneurysm development. One patient had a type A dissecting aortic aneurysm with a primary tear in the ascending thoracic aorta; the other 8 had type B dissection. Placement of an endovascular stent-graft was technically successful in 8 patients, and one underwent an open procedure for abdominal aortic fenestration. The entry site was sealed and the false lumen disappeared in 8 cases, and thrombosis of the false lumen was obtained. Rupture of an iliac artery dissecting aneurysm occurred in one patient 2 days after stent-graft placement; abdominal aortic fenestration with prosthetic replacement of the distal abdominal aorta was performed. One patient died of myocardial infarction 3 days after the stent-graft procedure. During a mean follow-up period of 7 months (1–16 months), one patient died of acute myocardial infarction at 11 months. It was concluded on the basis of these short-term results that endovascular repair of aortic dissection is a promising treatment, and abdominal aortic fenestration is a useful adjuvant procedure.
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INTRODUCTION
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Aortic dissection is the most common clinical condition affecting the aorta. After a tear in the intimal layer, the subsequent subintimal hematoma produces a false lumen or double-barreled aorta which is seriously life-threatening.Attendant complications such as bleeding from the aorta, rupture of the false lumen, aortic valve regurgitation, cerebrovascular ischemia, irreversible kidney failure, visceral ischemia, pericardial tamponade, and hypertension may occur singly or in combination and may be associated with increased morbidity and mortality. The recent advances in treatment of this condition have decreased the morbidity and mortality rates. However, aortic dissection remains a potential complication and a great therapeutic challenge.1 The use of an endovascular stent-graft to seal the proximal entry site and produce both reinforcement of the aortic wall and remodeling of the aortic lumen, offers a less invasive alternative to surgical graft replacement for patients with aortic dissection.2–5 In this series, an endovascular stent-graft was implanted to treat thoracoabdominal dissecting aortic aneurysm.
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PATIENTS AND METHODS
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Between October 2000 and January 2002, 9 consecutive male patients with subacute or chronic aortic dissection underwent stent-graft placement over the primary tear, with or without aortic fenestration, at the First Affiliated Hospital, Sun Yat-sen University. Ages ranged from 42 to 72 years (mean, 53.8 ± 10.6 years). All patients had symptoms of persistent severe back pain and hypertension. Table 1
lists the characteristics of these patients. The indication for intervention was continuous pain or aneurysm development. The interval between the onset of the primary clinical symptom and placement of the stent-graft was 1 to 6 months (mean, 3.1 ± 2.1 months). When the implantation procedure was performed, all patients were stabilized hemodynamically with antihypertensive therapy, and no rupture or bleeding was observed. Informed consent was obtained from the patients and their relatives.
Before the endovascular procedure, all patients underwent chest radiography and cross-sectional imaging of the chest and abdomen by spiral computed tomographic angiography, ultrafast computed tomographic angiography, and magnetic resonance angiography. Digital subtraction angiography was also used in 3 cases (Figure 1). All patients were found to have a false lumen, and the true aortic lumen was severely narrowed. The thoracoabdominal aorta was affected in all cases, extending distally below the iliac arteries in 3 of them. According to the Stanford classification of dissection, 1 patient had type A dissection with a primary tear in the ascending thoracic aorta, and the other 8 had type B dissection. The distance between the origin of the left subclavian artery and the primary tear varied from 0.8 to 4 cm for type B dissection (Table 1
).
A Talent stent-graft prosthesis (Medtronic AVE, Santa Rosa, CA, USA) was used in all cases. This self-expanding stent-graft consists of a circumferential nitinol wire stent shaped in a zigzag formation, arranged as a tube for conformance to the lumen, and covered with an extra-thin Dacron graft. A longitudinal nitinol wire interconnects the rings to ensure stabilization and separation of all the rings, and to avoid twisting or kinking. The stent-graft is preloaded in a polyurethane sheath for insertion and positioning, and it can be released by removing the sheath. A central catheter with an integrated balloon allows insertion over a guidewire and modeling of the prosthesis.
Stent-graft placement was performed in a radiological operating suite with the patient under general anesthesia. Patients were prepared to undergo surgery in case the procedure failed. A catheter was inserted into the radial artery for blood pressure monitoring and a jugular vein catheter was positioned for fluid administration. Antibiotic therapy was applied after anesthesia. A 6F pigtail catheter (Terumo Co., Tokyo, Japan) was introduced into the left brachial artery for precise guidance near the subclavian artery and for aortography during the procedure. The primary tear was located by initial angiography. The femoral artery or the distal external iliac artery was surgically exposed for vascular access in the 8 patients with type B dissection. In Case 2 with type A dissection, the left carotid artery was used for access and left subclavian-carotid artery bypass was established temporarily. The vessel was cut transversely and a guidewire was inserted. When the position of the wire in the true lumen of the aorta had been confirmed by fluoroscopy or by the catheter from the brachial artery, the stent-graft prosthesis was introduced. Under radiological guidance, the compressed stent was advanced to the appropriate position; part of the left subclavian artery may be covered by the bare end of spring. When the systolic blood pressure was decreased to 90 mmHg with sodium nitroprusside, the prosthesis was released and the stent was expanded by balloon molding, stopping blood flow into the false lumen. The stent-grafts implanted had diameters of 32–44 mm and lengths of 99–130 mm. In 2 patients, the covered portion of the stent-graft had to be over-stented with a second prosthesis in an overlapping manner, to achieve successful sealing of the primary tear.
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RESULTS
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Stent-graft deployment within the true lumen of the aorta was technically successful, and the entry to the false lumen was sealed in 8 of the 9 cases (Figure 2). Endovascular stent-graft implantation was abandoned in Case 1 because the celiac trunk and left renal artery were perfused from the false lumen. The strategy was converted to an open descending aortic fenestration procedure. Patient in Case 5 suffered from rupture of the false lumen of the right iliac artery 2 days after stent-graft placement; an adjunctive fenestration procedure was performed and a polytetrafluoroethylene prosthesis was connected to the femoral arteries. None of the patients died during the endovascular stent-graft procedure. The entry site was sealed and the false lumen disappeared in 8 cases, confirmed by angiography during the procedure. Thrombosis of the false lumen was obtained, as shown at follow-up by color duplex sonography. The early mortality was one patient (Case 4) who suffered from acute myocardial infarction 3 days after the stent-graft procedure. During a mean follow-up of 7 months (range, 1–16 months), one patient (Case 2) suffered from acute myocardial infarction and died 11 months after the procedure. There was no incidence of chest pain, stroke, or paraplegia in any of the other patients, and their hypertension was controlled with or without a low dose of antihypertensive agents.
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DISCUSSION
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The Stanford classification divides aortic dissections into 2 types: type A involves the ascending aorta and type B involves the descending aorta. Patients with aortic dissection can also be divided into subgroups. In those with acute aortic dissection, the mortality rate is 1%–2% per hour during the first 24–48 hours.1,6 Usually, type A dissections require surgery, while type B dissections may be managed medically under most conditions. Without treatment, proximal expansion might lead to cardiac tamponade or occlusion of coronary arteries with myocardial infarction, and distal expansion might cause occlusion of aortic branches resulting in acute aortic rupture or organ ischemia. For patients with subacute or chronic descending aortic dissection who survive under medical therapy for more than 14 days after the initial symptoms, impending aortic rupture or organ ischemia is ever present, and gradual enlargement of the false lumen occurs in more than 20%, with aneurysm formation as a late sequela. Recent advances in surgical repair and medical therapy for this condition have decreased the morbidity and mortality rates. Such advances include current surgical techniques, more impermeable grafts, the introduction of profound hypothermic circulatory arrest with retrograde cerebral perfusion, improvements in intensive care medicine, beta-blockers and other antihypertensive agents. However, surgical resection carries the risk of death or devastating complications such as spinal cord injury and paraplegia.1 Thus, an alternative approach has been sought to avoid major surgery and the related high morbidity and mortality.
Recently, the groups of Nienaber3 and Dake4 reported favorable early results of catheter-delivered endovascular stent-grafts for the treatment of aortic dissection. Our preliminary clinical results confirm that this technique is safe and effective. Endovascular stent-graft placement requires precise manipulation of catheters and positioning of the stent as well as state-of-the-art imaging technology. Although this therapy is catheter-based, aortic dissection remains a disease treated by surgeons. The management of this condition and its complications require seasoned surgical judgment and, in certain cases, surgical intervention, sometimes on an urgent basis. It should be emphasized that multidisciplinary efforts are involved in stent-graft implantation, requiring both surgeons and radiologists.
In cases complicated by underperfusion of the vital organs, the overall risk of descending aortic dissection is greatly increased. Aortic fenestration can effectively relieve organ ischemia.1 Experimental aortic fenestration also confirmed that fenestration of the aorta restored blood pressure and flow to hypoperfused organs in acute descending aortic dissection.7 One patient in this series, whose coeliac trunk and left renal artery originated from the false lumen, benefited from fenestration of his descending aortic dissection. Aortic fenestration is a useful addition to endovascular treatment for patients with ischemic complications or rupture of a distal aneurysm of the descending aortic dissection.8 It was concluded from these short-term results that endovascular repair of aortic dissection is promising, and the nonsurgical reconstruction concept should be assessed by a randomized long-term study.
Presented at the 5th International Congress of the Asian Vascular Society, Singapore, May 23–26, 2002.
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REFERENCES
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ABSTRACT
INTRODUCTION
