Ann Thorac Surg 2009;88:2029-2031. doi:10.1016/j.athoracsur.2009.04.086
© 2009 The Society of Thoracic Surgeons
Case Reports
Intimal Tear After Endovascular Repair of Chronic Type B Aortic Dissection
Shuji Chino, MDa,*,
Noriyuki Kato, MDa,
Takatsugu Shimono, MDb,
Kan Takeda, MDa
a Department of Radiology, Mie University Hospital, Mie, Japan
b Department of Thoracic and Cardiovascular Surgery, Mie University Hospital, Mie, Japan
Accepted for publication April 21, 2009.
* Address corresponding to Dr Chino, Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514, Japan (Email: shuspa{at}clin.medic.mie-u.ac.jp).
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Abstract
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Two patients with chronic type B aortic dissection underwent endovascular repair. The interval between the onset of aortic dissection and stent grafting was 1 year, 7 months in both patients. The entry closure was successful and postoperative course was uneventful for each patient. However, intimal injury developed at the bottom end of the stent graft 6 years after endovascular repair in 1 patient, and at 2 years in the other patient. The former patient underwent graft replacement of the descending thoracic aorta, and the latter underwent placement of additional stent grafts.
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Introduction
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Stent graft repair has become the first choice of the treatment in patients with a wide range of aortic diseases. Above all entry closure with endovascular repair, stent graft placement is now recognized as an attractive alternative to surgical intervention for the treatment of patients with aortic dissection. Stent grafting especially seems more promising in cases with chronic dissection, because aorta-related complications after the procedure rarely occur in these cases.
In this report, we describe our experience of intimal injury after stent grafting in two cases with chronic aortic dissection.
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Case Reports
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Patient 1
A 64-year-old man with chronic type B aortic dissection underwent stent graft repair, because the diameter of the descending thoracic aorta reached 64 mm (Figs 1 and 2).
The interval between the onset of aortic dissection and the treatment was 1 year, 7 months. The longer and the shorter diameter of the proximal site of the landing zone were 40 mm and 35 mm, whereas those of the distal site were 38 mm and 16 mm, respectively. A stent graft that was made of Z-stents (Cook Medical Inc, Bloomington, IN) and expanded polytetrafluoroethylene (Impra Inc, Tempe, AZ) was used for entry closure. The diameter of the device was 40 mm at the top and 34 mm at the bottom, whereas the total length was 12.5 cm. Completion aortography showed no endoleak and a postoperative computed tomographic image showed complete thrombosis of the false lumen of the descending thoracic aorta.
The postoperative course of this patient was uneventful, and the diameter of the descending aorta had been unchanged for 5 years. However, a computed tomographic scan was obtained at 6 years after the treatment, which showed an inflow of contrast media into the false lumen at the distal end of the stent graft. Because the inflow into the false lumen was subtle, he was observed conservatively for 2 years. However, the diameter of the descending aorta finally reached 83 mm (Fig 3). He underwent graft replacement of the descending thoracic aorta and tolerated it well.
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Fig 3. Aortography performed 8 years after stent grafting shows inflow of contrast medium into the false lumen (arrow).
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Patient 2
A 67-year-old woman who had history of graft replacement of the proximal descending aorta for the treatment of type B aortic dissection was sent to us because the diameter of the distal descending aorta reached 60 mm during follow-up. A preoperative computed tomographic image showed the entry tear was located below the graft. The diameter of the graft was 25 mm. The longer and the shorter diameter of the distal site of the landing zone were 32 mm and 11 mm, respectively. A stent graft made of Z-stents and polyester (UBE, Tokyo, Japan) was used for entry closure. The diameter and length of the device were 28 mm and 10 cm, respectively. Her postoperative course was uneventful and the aortic diameter had been unchanged at the 1-year follow-up.
However, a computed tomographic scan was obtained 2 years after the treatment, which showed an endoleak at the bottom end of the stent graft and aortic expansion to 68 mm. She underwent additional endovascular repair with a Gore TAG device (W. L. Gore and Associates, Flagstaff, AZ) and tolerated the procedure well.
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Comment
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Nienaber and colleagues [1] compared stent graft repair with surgical graft replacement in patients with chronic type B aortic dissection. In their series, no deaths or major complications were observed in the group of stent graft repair, whereas there were four deaths and five serious adverse events in the group of surgical repair. Although the number of patients was extremely limited, there was a significant difference in operative mortality and morbidity between the two groups.
There have been several similar reports that describe effectiveness of stent graft repair in patients with chronic type B dissection [2]. This is not surprising because stent graft repair is far less invasive than surgical repair, which often requires extensive resection of the descending thoracic aorta and is associated with severe morbidities, including respiratory failure, renal failure, and spinal ischemia.
It is well known that the dissected flap, which is extremely fragile in the acute phase, seemingly became stable in the chronic phase [3]. Indeed, it is not rare that aorta-related complications (including intimal injury) can be observed when acute aortic dissection is treated with a stent graft [4, 5]. In contrast, such complications are not usual in cases with chronic dissection. We had treated 47 patients with chronic type B dissection with stent grafting. The two cases described herein are the only cases in which intimal injury was observed. How and in which patients intimal injury can develop are not clear. Various factors, such as the age of aortic dissection, configuration of stent grafts against the intimal flap, hoop strength of stent grafts, and the ratio of oversizing could contribute to the complication. Since the ages of aortic dissection were older than 1 year, and the landing zone were at the straight portion of the descending aorta, hoop strength and oversizing may have played an important role in our 2 patients.
Some insist that the whole dissected descending aorta be covered with stent grafts. However, we have to disagree with their strategy, because even after covering the whole descending aorta, there still remains a chance of intimal injury at the bottom end of the stent grafts as far as the dissection extend to the abdominal aorta. Therefore, we use the stent grafts, which are long enough to only close the primary entry tear.
It is well known that the hoop strength of Z-stents is relatively larger than that of TAG (W. L. Gore and Associates). Therefore, collapse which sometimes develops with the TAG device, is rarely seen with homemade stent grafts made of Z-stents [6]. Instead, the firm hoop strength of Z-stents potentially makes intimal injury more frequently than TAGs. Generally, oversizing by 10% to 20% seems to be necessary in dealing with an aortic aneurysm. However, in our patients, oversizing of the device at the bottom end was 26% (patient 1) and 30% (patient 2). Because we expected that the intimal flap should dilate to the diameter close to that of the proximal site, we adopted such oversizing. However, the fibrotic intimal flap was not compliant enough to dilate after the expansion of the too much oversized stent grafts. From this speculation, appropriately tapered stent grafts would be favorable in the treatment of chronic dissection to avoid postoperative intimal injury. Most of intimal injury developed within 3 months in patients with acute dissections [7]. In contrast, it developed 6 years after the treatment in 1 patient and 2 years in the other patient. Therefore, further intensive follow-up seems to be mandatory in cases with chronic dissection, compared with cases of acute dissection.
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References
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- Nienaber CA, Fattori R, Lund G, et al. Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement N Engl J Med 1999;340:1546-1552.[Medline]
- Nienaber CA, Rehders TC, Ince H. Interventional strategies for treatment of aortic dissection J Cardiovasc Surg 2006;47:487-496.[Medline]
- Kato N, Shimono T, Hirano T, et al. Midterm results of stent-graft repair of acute and chronic aortic dissection with descending tear: the complication-specific approach J Thorac Cardiovasc Surg 2002;124:306-312.[Abstract/Free Full Text]
- Leurs L, Bell R, Degrieck Y, Thomas S, Hobo R, Lundbom J. Endovascular treatment of thoracic aortic diseases: Combined experience from the EUROSTAR and United Kingdom Thoracic Endograft Registries J Vasc Surg 2004;40:670-680.[Medline]
- Shang DX, Fang JH, Jin FY, et al. Endovascular repair of acute type B aortic dissection: Early and mid-term results J Vasc Surg 2006;43:1090-1095.[Medline]
- Arslan B, Turba UC, Matsumoto AH. Thoracic aortic endograft collapse after endovascular treatment of a traumatic pseudoaneurysm Semin Interv Radiol 2007;24:279-287.
- Kato N, Hirano T, Kawaguchi T, et al. Aneurysmal degeneration of the aorta after stent-graft repair of acute aortic dissection J Vasc Surg 2001;34:513-518.[Medline]
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Abstract
Introduction
