Ann Thorac Surg 2005;79:1245-1249
© 2005 The Society of Thoracic Surgeons
Original articles: Cardiovascular
Risk of Spinal Cord Injury After Operations of Recurrent Aneurysms of the Descending Aorta
Jorge Flores, MD,
Norihiko Shiiya, MD, PhD,
Takashi Kunihara, MD, PhD*,
Kenji Matsuzaki, MD,,
Keishu Yasuda, MD, PhD
Department of Cardiovascular Surgery, Hokkaido University School of Medicine, Hokkaido, Japan
Accepted for publication September 21, 2004.
* Address reprint requests to Dr Kunihara, Kita 14 Jo, Nishi 5 Choume, Kita-Ku, Sapporo, Hokkaido, Japan, 060–8648 (E-mail: kunihara{at}med.hokudai.ac.jp).
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Abstract
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BACKGROUND: Degenerative disease of the aorta usually involves the occlusion of several intercostal and lumbar branches by mural thrombus or atherosclerotic plaques, suggesting that the blood supply to the spinal cord is mainly provided through collateral networks. Patients with previous abdominal aortic aneurysm repair and subsequent thoracoabdominal aortic reconstruction must undergo ligation of a number of these segmental arteries, presenting a greater risk of experiencing spinal cord ischemic injury.
METHODS: The records of 18 patients who had experienced abdominal aortic aneurysm graft replacement and who had undergone 19 operations for thoracoabdominal aortic repair were retrospectively evaluated. All patients were male. The mean age was 66 ± 10 years (range, 36 to 75 years); the mean interval between the two operations was 79 ± 69 months (range, 1 to 231 months). There were 18 (95%) cases of thoracoabdominal aortic aneurysms, and one (5%) case of acute dissection of the thoracoabdominal aorta. The origin of the Adamkiewicz artery was determined preoperatively by computed tomography. Measures to avoid spinal cord injury included monitoring of evoked spinal cord potentials and selective reconstruction of the intercostal arteries under hypothermic cardiopulmonary bypass.
RESULTS: There were three (16%) cases of permanent neurologic injury that included one cerebrovascular accident, one neurogenic bladder, and one paraparesis of the right lower limb. There were no cases of paraplegia or postoperative deaths.
CONCLUSIONS: Surgical reconstruction of the thoracoabdominal aorta in patients who previously underwent abdominal aortic graft replacement is not related to an increased probability of developing spinal cord ischemic injury.
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Introduction
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Degenerative aortic aneurysm is associated with the occlusion of several lumbar and intercostal arteries by mural thrombus or atherosclerotic plaques [1]. Patients with a history of abdominal aortic aneurysm (AAA) repair who undergo reconstruction of the descending aorta present a greater risk of experiencing spinal cord ischemic injury compared with patients without this precedent, taking into account the reduced number of potential feeders to the spinal cord blood flow by the degenerative process as well as further ligation of patent branches during the two surgeries.
According to previous studies, the incidence of aortic aneurysms that develop proximal to an AAA graft replacement fluctuate from 3% to 8% [2, 3]. Coselli and associates [4], in the largest series of patients evaluated on this subject, reported an interval of 8.2 years between operations, with rates of 4.1% for postoperative paraplegia and 8.1% for paraparesis. Other commonly mentioned postoperative complications are related to renal failure (5% to 19%), respiratory failure (5% to 17%), and bleeding (7% to 10%); perioperative death fluctuates from 12% to 28% [4–6].
Considering the variable origin of the Adamkiewicz artery (arteria radicularis magna; ARM) and the unpredictable anatomy of the lumbar and intercostal arteries that perfuse the spinal cord [1, 7, 8], we evaluated the probability of developing spinal cord ischemic injury in patients who underwent reoperations of the descending aorta after AAA graft replacement.
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Material and Methods
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Patient Population
From January 1990 to January 2004, 39 patients, who had previously endured AAA graft replacement, underwent subsequent surgical repair of a proximal aortic lesion. All of those patients who underwent graft replacement of the thoracoabdominal aorta were included in this study (18 patients). Patients who experienced aneurysm, dissection, or dissecting aneurysm of the aortic arch (16 patients), as well as those with paraanastomotic pseudoaneurysm (4 patients) and an infected pseudoaneurysm (1 patient), were excluded.
All patients were male (100%), with a mean age of 66 ± 10 years (range, 36 to 75 years). Preoperative risk factors included previous cerebrovascular accident in 6 patients (33%), history of ischemic heart disease in 7 patients (39%; 6 patients who had undergone previous coronary artery bypass grafting and 1 patient with previous percutaneous transluminal coronary angioplasty), hypertension in 16 patients (89%), hyperlipidemia in 10 patients (56%), history of smoking in 15 patients (83%), and chronic obstructive pulmonary disease in 9 patients (50%). Renal dysfunction, defined by a serum creatinine level of 2 mg/dL or greater [9], was present in 5 patients (28%); there were no patients with diabetes mellitus (Table 1).
All patients (100%) underwent previous infrarenal AAA repair, Y-graft replacement was performed in 17 patients, and straight-graft replacement in 1 patient. The mean interval between operations was 79 ± 69 months (range, 1 to 231 months). There were 18 (95%) cases of thoracoabdominal aortic aneurysm, which included 9 cases of chronic dissections that became aneurysmal; all of the operations were performed on a scheduled basis. We performed only one (5%) emergency operation, which was an acute dissection of the thoracoabdominal aorta without aneurysmal dilatation. Characteristics of the thoracoabdominal aortic aneurysms are presented in Table 2.
Protocol for Spinal Cord Protection
We previously described the surgical technique for thoracic and thoracoabdominal aortic aneurysm repair [10]. Basically, we used the same protocol to avoid neurologic ischemic injury in patients undergoing thoracoabdominal aortic surgery for the first time as well as in cases of reoperations. Briefly, our strategy consists of the following procedures: (1) distal aortic perfusion using a femoral vein-to-femoral artery (femorofemoral) partial cardiopulmonary bypass (CPB) under mild hypothermia (32° to 34°C); (2) multiple segmental sequential clamping that allows the intercostal and lumbar arteries below the distal clamp to be perfused by the distal partial CPB, to decrease the rate of spinal cord ischemia; (3) open proximal anastomosis under deep hypothermic circulatory arrest (18° to 22°C) in the case of mobile atheroma, which could develop antegrade or retrograde embolization at the time of aortic clamping, or when the quality of the aortic wall is inadequate for sequential clamping; (4) administration of naloxone hydrochloride and methylprednisolone; (5) cerebrospinal fluid drainage; (6) a preoperative identification of the origin of the ARM by multidetector row computed tomography (MDCT) [11], which has just recently been introduced; (7) selective reconstruction of the origin of the ARM and any segmental branch that demonstrates ischemic changes by evoked spinal cord potential (ESP) monitoring after resection of the aortic segment of origin [12]; (8) beveling the end of the aortic prosthesis in an attempt to reduce the number of sacrificed segmental branches of the aorta; and (9) during reconstruction of the aorta and its critical segmental arteries, stopping the backbleeding from these arteries by small balloon catheters to improve the blood supply to the spinal cord.
We classified the neurologic complications as transient or permanent. Transient neurologic complications were those neurologic dysfunctions that lasted for a determined period of time and then allowed a complete recovery by the patient. Permanent neurologic complications were defined as the presence of neurologic deficits that persisted even after discharge from the hospital. Paraparesis was defined as weakness in preserving motion against gravity or resistance, and more severe deficits were classified as paraplegia.
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Results
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The mean operative time was 549 ± 246 minutes (range, 154 to 1,053 minutes). The mean CPB time was 187 ± 123 minutes (range, 34 to 458 minutes). The mean aortic cross-clamping time was 109 ± 52 minutes (range, 32 to 220 minutes). The mean blood loss was 6,387 ± 7,863 mL (range, 190 to 25,544 mL), and the mean blood transfusion was 5,070 ± 6,380 mL (range, 200 to 19,349 mL). Two patients had intraoperative bleeding from the cannulation sites in the aortic wall; as a result of the hemostatic maneuvers, the operation lasted longer than 17 hours in both cases, increasing the mean time of several intraoperative variables in this series. The mean period of stay in the intensive care unit was 5 ± 5 days (range, 2 to 21 days), and the mean time of the patients' connection to a ventilator was 3 ± 4 days (range, 1 to 18 days). The cause was arteriosclerosis in 16 cases, medial cystic necrosis in one case, and Marfan syndrome in one case.
Operation
All patients underwent open graft replacement of the diseased segment of the thoracoabdominal aorta. Among the 19 thoracoabdominal aortic reconstructions and according to our criteria for reanastomosis, the segmental branches at T3, T4, T12, and L2 levels were reconstructed in one case; T6 and T9 were reconstructed in two cases; T7, T8, and T11 were reconstructed in three cases; and T10 and T11 were reconstructed in four cases. The left subclavian artery was reanastomosed in one case, the celiac trunk in four cases, the superior mesenteric artery in five cases, the right renal artery in four cases, and the left renal artery in four cases.
Adjuncts to Avoid Neurologic Ischemic Damage
The origin of the ARM was successfully identified in 6 (75%) of the 8 patients who underwent preoperative MDCT. Intraoperative monitoring of ESP was applied in all but 4 patients: the patient who underwent emergency operation and 3 additional patients with inadequate deployment of electrodes in the epidural space. Selective visceral and spinal cord perfusion as well as cerebrospinal fluid drainage were performed on all patients.
Mild hypothermic femorofemoral partial CPB and sequential aortic clamping were performed in 10 (56%) cases. In six (33%) cases, aortic repair was performed under deep hypothermic total CPB, with circulatory arrest during the open proximal aortic anastomosis; then blood perfusion to the upper body was reestablished through a branch of the aortic graft and to the lower body through a femorofemoral bypass, with sequential aortic clamping during the distal reconstruction. One (6%) case of Crawford/Safi V thoracoabdominal aortic aneurysm underwent the operation under selective visceral perfusion by a catheter deployed at the proximal healthy aorta to irrigate the abdominal visceral branches without using another adjunct.
Two (11%) cases involved histories of ischemic heart disease, which precluded the use of deep hypothermic circulatory arrest. These patients' aortic walls, which seemed very weak, and the presence of mobile atheroma prevented sequential clamping. Instead, these patients underwent the aortic graft replacement under partial CPB, maintaining the upper body temperature at mild hypothermia (32°C) to decrease the metabolic demands of the myocardium and brain, thus avoiding heart fibrillation, which appears at less than 25°C and is not well tolerated in the case of coronary arterial disease [13, 14]. Because the distal descending aorta was large and weak, precluding sequential repair, the lower body was subjected to deep hypothermia (18°C) to provide adequate protection to the spinal cord and abdominal viscera during the aortic reconstruction (Table 3).
Neurologic Complications
All patients underwent postoperative neurologic examination for diagnosis of neurologic complications. There were nine (47%) cases of postoperative neurologic complications. Six (32%) patients experienced transient delirium developed after awakening from the anesthesia, and all of them were neurologically normal when they left the intensive care unit. There were three (16%) cases of permanent neurologic complications. The only patient who received an emergency operation in our series did not undergo preoperative MDCT or intraoperative ESP monitoring and experienced right leg paraparesis. In 1 patient, the ARM origin could not be identified by MDCT, and the ESP device failed to record the spinal cord function intraoperatively; this patient presented a neurogenic bladder. Another patient, who had a cerebrovascular accident, did not undergo preoperative MDCT, but his ESP monitoring did not show any ischemic change during the aortic reconstruction. There were no cases of paraplegia (Table 4).
Other Postoperative Complications
There were 10 (56%) cases of respiratory complications: four cases of respiratory failure that required prolonged ventilatory support (
72 hours), three cases of pneumonia, two cases of chylothorax, and one case of lung atelectasis. One (5%) patient had a pleural empyema and had undergone reoperation for toilet with saline solution and omental wrapping of the aortic graft. Four (21%) patients experienced hemorrhagic complications: there were three hemothorax and one retroperitoneal hematoma. Two of the patients with hemothorax underwent reexploration, and the other 2 responded well to conservative treatment. Six (32%) patients experienced transient liver dysfunction. Three (16%) patients presented with renal failure; 2 were transient and 1 was a patient with preoperative chronic renal failure whose condition worsened. There were no perioperative deaths, and all of the patients were still living when discharged.
Long-Term Follow-Up
The mean follow-up was 41 ± 34 months (range, 2 to 120 months). During the follow-up 4 patients died: 1 patient died 38 months postoperatively of cardiac infarction after coronary artery bypass grafting, 1 patient died after 25 months of gall bladder cancer, 1 patient died 63 months postoperatively of lung cancer, and the patient who experienced postoperative cerebrovascular accident died after 2 months of pneumonia. Overall survival by Kaplan-Meier analysis was 77.2% ± 12.1% at 5 years and 57.7% ± 19.0% at 10 years (Fig 1).
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Fig 1. Kaplan-Meier survival curve after thoracoabdominal aortic aneurysm reconstruction in patients with precedent of abdominal aortic aneurysm repair, along with numbers showing patients at risk.
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Comment
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Neurologic deficit after thoracoabdominal aortic repair is the consequence of a temporary or permanent interruption of the spinal cord blood supply that is mainly provided by the ARM, with the addition of collateral networks [15, 16]. The ARM enters the vertebral canal between T9 and T12 in 75% of cases, between L1 and L3 in 10% of cases, and between T5 and T8 in 15% of cases [17]. Collateral suppliers are related to the subclavian artery by the vertebral and ascending cervical arteries, and to the hypogastric artery by the iliolumbar and lateral sacral arteries [8, 17]. Patients in our series presented a limited number of patent segmental arteries to preserve adequate blood supply to the spinal cord; for this reason, it was essential to carefully identify and reconstruct these branches.
According to the formula of LeMaire and colleagues [18] for predicting the number of cases of neurologic deficit in a group of patients after thoracoabdominal aortic aneurysm repair, the expected number in our group was 0.47; however, we actually experienced two (10.5%) cases of distal neurologic deficit. Although we consider this outcome acceptable and in line with recently published data [15, 19], it was higher than predicted and should be attributed to the precedent of AAA repair.
Preoperative MDCT allowed the identification of the ARM origin in 75% of patients who participate in this study. Reconstruction of this branch, in addition to only those segmental arteries that showed ischemic changes by ESP monitoring after temporary balloon occlusion, helped to reduce the aortic reconstruction time and thus minimized the degree and duration of spinal cord ischemia. The principle of ESP monitoring led us to reanastomose intercostal branches, in some cases quite proximal, at the T3 and T4 levels. Furthermore, beveling the end of the aortic prosthesis prevented reanastomosis of critical segmental branches in 8 of our patients. It is remarkable that neither MDCT nor ESP monitoring could be performed in the 2 patients with neurologic deficits attributable to spinal cord ischemia, and the patient with postoperative cerebrovascular accident possibly experienced retrograde embolization of atheromatous debris.
In conclusion, based on our experience, we assume that patients who undergo thoracoabdominal aortic reconstruction after AAA repair are related to a relatively low incidence of postoperative neurologic deficit. This fact is probably associated with the enlargement in the blood supply from previous secondary collateral pathways during the progression of the aortic disease as well as our multimodality approach to preserving the spinal cord blood supply during aortic reconstruction. The main feeder branches should be carefully identified by preoperative MDCT and intraoperative ESP monitoring and then selectively reimplanted to decrease the period and magnitude of ischemia to the spinal cord during the aortic manipulation.
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References
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- Jacobs MJ, de Mol BA, Elenbass T, et al. Spinal cord blood supply in patients with thoracoabdominal aortic aneurysms J Vasc Surg 2002;35:30-37.[Medline]
- Edwards JM, Teefey SA, Zierler E, Kohler TR. Intraabdominal paraanastomotic aneurysms after aortic bypass grafting J Vasc Surg 1992;15:344-353.[Medline]
- Plate G, Hollier LA, O'Brien P, Pairolero PC, Cherry KJ, Kazmier FJ. Recurrent aneurysms and late vascular complications following repair of abdominal aortic aneurysms Arch Surg 1985;120:590-594.[Abstract/Free Full Text]
- Coselli JS, LeMaire SA, Buket S, Berzin E. Subsequent proximal aortic operations in 123 patients with previous infrarenal abdominal aortic aneurysm surgery J Vasc Surg 1995;22:59-67.[Medline]
- Fox AD, Berkowitz HD. Thoracoabdominal aneurysm resection after previous infrarenal abdominal aortic aneurysmectomy Am J Surg 1991;162:142-144.[Medline]
- Curl GR, Faggioli GL, Stella A, D'Addato M, Ricotta JJ. Aneurysmal change at or above the proximal anastomosis after infrarenal aortic grafting J Vasc Surg 1992;16:855-860.[Medline]
- Griepp RB, Ergin MA, Galla JD, et al. Looking for the artery of Adamkiewicz: A quest to minimize paraplegia after operations for aneurysms of the descending thoracic and thoracoabdominal aorta J Thorac Cardiovasc Surg 1996;112:1202-1215.[Abstract/Free Full Text]
- Picone AL, Green RM, Ricotta JR, May AG, DeWesse JA. Spinal cord ischemia following operations on the abdominal aorta J Vasc Surg 1986;3:94-103.[Medline]
- Crawford ES, Crawford JL, Safi HJ, et al. Thoracoabdominal aortic aneurysm: Preoperative and intraoperative factors determining immediate and long-term results of operations in 605 patients J Vasc Surg 1986;3:389-404.[Medline]
- Yasuda K, Shiiya N, Miyatake T, Matsuzaki K, Kunihara K. Surgical results of thoracic and thoracoabdominal aortic aneurysm repair: a 12-year experience with 332 aneurysms in Hokkaido University HospitalIn: Yasuda K, Sasaki S, editors. Advances in vascular surgery. Hokkaido: Hokkaido University Press; 2003. pp. 3:45–70.
- Maruyama R, Kamishima T, Shiiya N, et al. MDCT Scan visualizes the Adamkiewicz artery Ann Thorac Surg 2003;76:1308.[Free Full Text]
- Shiiya N, Yasuda K, Matsui Y, Sakuma M, Sasaki S. Spinal cord protection during thoracoabdominal aortic aneurysm repair: results of selective reconstruction of the critical segmental arteries guided by evoked spinal cord potential monitoring J Vasc Surg 1995;21:970-975.[Medline]
- Okita Y, Takamoto S, Ando M, et al. Repair for aneurysms of the entire descending thoracic aorta or thoracoabdominal aorta using a deep hypothermia Eur J Cardiothorac Surg 1997;12:120-126.[Abstract]
- von Segesser LK, Marty B, Mueller X, et al. Active cooling during open repair of thoraco-abdominal aortic aneurysms improves outcome Eur J Cardiothorac Surg 2001;19:411-416.[Abstract/Free Full Text]
- Coselli JS, LeMaire SA, Conklin LD, Adams GJ. Left heart bypass during descending thoracic aortic aneurysm repair does not reduce the incidence of paraplegia Ann Thorac Surg 2004:1298-1303.
- Biglioli P, Roberto M, Cannata A, et al. Upper and lower spinal cord blood supply: the continuity of the anterior spinal artery and the relevance of the lumbar arteries J Thorac Cardiovasc Surg 2004;127:1188-1192.[Abstract/Free Full Text]
- Lazorthes G, Gouaze A, Zadeh JO, Santini JJ, Lazorthes Y, Burdin P. Arterial vascularization of the spinal cordRecent studies of the anastomotic substitution pathways. J Neurosurg 1971;35:253-262.
- LeMaire SA, Miller III CC, Conklin LD, Schmittling ZC, Coselli JS. Estimating group mortality and paraplegia rates after thoracoabdominal aortic aneurysm repair Ann Thorac Surg 2003;75:508-513.[Abstract/Free Full Text]
- Safi HJ, Miller III CC, Estrera AL, et al. Chronic aortic dissection not a risk factor for neurologic deficit in thoracoabdominal aortic aneurysm repair Eur J Vasc Endovasc Surg 2002;23:244-250.[Medline]
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INVITED COMMENTARY
- R. Scott Mitchell
Ann. Thorac. Surg. 2005 79: 1249.
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Abstract
Introduction
