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J Thorac Cardiovasc Surg 2001;122:1240-1243
© 2001 The American Association for Thoracic Surgery
Brief Communications |
From the Departments of Cardiothoracic Surgerya and Human Pathology,b University of Tokyo, Tokyo, Japan.
Received for publication Feb 28, 200l. Accepted for publication April 19, 2001. Address for reprints: Takeshi Miyairi, MD, PhD, Department of Cardiothoracic Surgery, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, 113-8655 Tokyo, Japan (E-mail: tmiyairi-tky{at}umin.ac.jp).
Open surgery with an endovascular stent graft is a novel therapeutic technique for aortic aneurysm that is especially useful for aneurysms of the distal arch. In this report we describe the clinical course and autopsy findings of 2 patients who had paraplegia after undergoing this procedure and died during the hospital stay.
Clinical summary
Patient 1
A 78-year-old man had angina pectoris and intermittent claudication. Angiograms revealed a thoracic aortic aneurysm in the distal part of the aortic arch involving the left subclavian artery, severe stenosis in the right coronary and left circumflex arteries, and total occlusion of both superficial femoral arteries. After median sternotomy and establishment of cardiopulmonary bypass, bypass grafts to the 2 coronary arteries were performed during perfusion cooling. During hypothermic circulatory arrest at a tympanic temperature of 18°C and retrograde cerebral perfusion, the aortic arch was transected between the left common carotid artery and the left subclavian artery. A stent graft, which was constructed from a 40 x 50-mm self-expandable Gianturco Z-shaped stent (William Cook Europe, Bjaeverskov, Denmark), covered with the distal part of a 32.5-mm thin-walled woven Dacron graft, was delivered into the descending aorta by means of a 30F sheath catheter with the distal end located 5 cm below the aneurysm. The proximal end of the stent graft was sutured to the wall of the transected aortic arch (Figure 1, A). A 26-mm collagen-coated woven Dacron graft with 4 branches was connected to the stent graft, and 3 arch vessels were reconstructed with the branches of the graft. Under systemic and hemi-selective cerebral perfusion through the fourth branch, the proximal anastomosis was completed(Figure 1
, B) and the heart was reperfused. The cardiopulmonary bypass, aortic crossclamp, and circulatory arrest times were 317 minutes, 190 minutes, and 80 minutes, respectively.
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At autopsy, there were no abnormal findings in the placement of the stent graft, the anastomoses, or the reconstruction of the 3 arch vessels. The aneurysmal cavity was occluded with thrombus. The Adamkiewicz artery was confirmed as the ninth intercostal artery by its characteristic hairpin curve just before connecting with the anterior spinal artery (Figure 2, A). The orifice of the Adamkiewicz artery was located 1 cm below the distal end of the stent graft(Figure 2, B). Histologic examination revealed disappearance of neuronal cells and axonal swelling of the lateral and posterior segments of the spinal cord at the level of the fourth spinal anterior thoracic root. Neither thrombus nor embolus was observed in any of the arteries.
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, C). The proximal end of the stent graft was sutured inclusively to the posterior wall and exclusively to the anterior wall of the ascending aorta, and the aortotomy was closed(Figure 1, D). The cardiopulmonary bypass time and circulatory arrest time for the lower part of the body were 286 minutes and 67 minutes, respectively. Hemodynamics immediately after bypass were unstable, with an arterial blood pressure of about 80 mm Hg for 2 hours. Postoperatively, incomplete tetraplegia with loss of superficial and deep sensation below the level of the fourth thoracic vertebra and motor dysfunction below the seventh were observed. Cerebrospinal fluid drainage was performed for 6 days. Although motion of the upper extremities gradually improved, that of the lower extremities remained unchanged. The patient had postoperative mediastinitis and died on postoperative day 31.
At autopsy, there appeared to be no problems in the placement and anastomosis of the stent graft, and all 3 arch vessels were patent. The aneurysm was completely occluded with thrombus. The Adamkiewicz artery was confirmed as the twelfth intercostal artery 4 cm below the stent graft. Histologic examination revealed diffuse spinal infarction in the central to the anterior segments of the spinal cord, all continuous from the level of C6 to Th11. Disappearance of neuronal cells and spongiosis with form cell infiltration was prominent. A few clusters of cholesterin embolus occluding arteries that drained into the anterior or posterior spinal artery at the level of C8 and Th6 were also observed (Figure 3).
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Open surgery with an endovascular stent graft used for aortic arch aneurysm, first reported by Kato and colleagues, 1 has several advantages over conventional prosthetic replacement. Substitution of stent-graft placement for distal anastomosis substantially reduces operative time, bleeding, and injury to adjacent organs resulting from dissection. As compared with catheter-based stent grafting, this method is especially useful for those distal arch aneurysms adjacent to or even including the origin of the left subclavian artery, where proximal landing space is difficult to obtain. Since 1996, we 2 have applied this method to 19 high-risk patients with distal aortic arch aneurysms with a fair hospital mortality (10.5%). However, 4 patients had postoperative paraplegia, with 2 hospital deaths. Although the etiology of paraplegia resulting from this method is not yet clear, the autopsy findings of these 2 cases were very informative.
Blood supply from the Adamkiewicz artery, which perfuses the anterior two thirds of the spinal cord, is thought to be highly associated with paraplegia after aortic surgery. In the 2 cases presented here, however, the orifices of the Adamkiewicz arteries, which were clearly confirmed by anatomic observation at autopsy, were not blocked by the stent graft. Therefore, impairment of blood flow of the Adamkiewicz arteries is not believed to be the cause of postoperative paraplegia.
Kato and colleagues 3 reported that among 26 patients with thoracic aortic aneurysms treated with this method, spinal cord injury was observed in only 1 patient who underwent a prolonged circulatory arrest time.
In patient 1, the circulatory arrest time was rather long (80 minutes at a tympanic temperature of 18°C). However, in our experience this duration of arrest is usually tolerable in patients undergoing conventional aortic surgery. In addition, histologic findings of a very limited area of spinal cord infarction—apart from the level of the Adamkiewicz artery—suggest that there should be some local impairment of spinal cord circulation intraoperatively, although neither thrombus nor embolus was observed in the specimen. In patient 2, a few cholesterin emboli found in the anterior spinal artery might be at least partly responsible for impaired blood flow to the spinal cord. These cholesterin emboli are believed to have been generated from the atherosclerotic aortic wall during stent-graft delivery. It has been reported that catheter-based stent grafting for aneurysms in the descending aorta is also associated with a substantial incidence of paraplegia and stroke, suggesting a potential hazard associated with insertion of the delivery sheath into the diseased aorta. 4,5 In patient 2, however, histologic examination demonstrated diffuse spinal cord infarction continuous from the level of C6 to Th11, suggesting intraoperative global ischemia of the spinal cord. Because of hemodynamic instability, the patient remained hypotensive immediately after bypass, a situation that is reported to be strongly associated with impairment of the spinal cord circulation. 6
In summary, these case reports demonstrate that paraplegia in patients undergoing open surgery with placement of an endovascular stent graft for aortic arch aneurysm may occur without interruption of blood flow to the Adamkiewicz artery. Every effort should be made to shorten the ischemic time of the spinal cord, to maintain stability of the perioperative hemodynamics, and to avoid generating cholesterin embolus from the atheromatous aorta, which is also a possible cause of spinal cord injury during catheter-based stent grafting.
Acknowledgments
We thank Prof Dr Reinhard Horvat for his assistance with the manuscript.
References
This article has been cited by other articles:
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  K. Toda, K. Taniguchi, H. Hata, Y. Shudo, H. Matsue, S. Kuki, and Y. Sawa Single-stage repair of arch aneurysms with a long elephant trunk: Medium-term follow-up of thromboexcluded aneurysms J. Thorac. Cardiovasc. Surg., July 1, 2007; 134(1): 47 - 52. [Abstract] [Full Text] [PDF]
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R. Kunitomo, S. Tsurusaki, H. Sakaguchi, I. Ideta, K. Takaji, Y. Katayama, and M. Kawasuji A simple method of intraoperative preparation of a stent graft for distal aortic arch aneurysm J. Thorac. Cardiovasc. Surg., June 1, 2003; 125(6): 1535 - 1537. [Full Text] [PDF]
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 T. Miyairi, Y. Kotsuka, M. Ezure, M. Ono, T. Morota, H. Kubota, K. Shibata, K. Ueno, and S. Takamoto Open stent-grafting for aortic arch aneurysm is associated with increased risk of paraplegia Ann. Thorac. Surg., July 1, 2002; 74(1): 83 - 89. [Abstract] [Full Text] [PDF]
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