Thoracoabdominal Aortic Reconstruction Research Articles

Connective tissue disease type mediates branch patency of grafts in open thoracoabdominal aortic reconstruction.

Despite a shared degenerative vascular phenotype, Marfan syndrome (MFS), Loeys-Dietz syndrome (LDS), and other genetically distinct connective tissue diseases (CTDs) have unique extravascular pathologies that impact the outcomes of aortic replacement. The aim of our study was to investigate the association of CTD genotype with postoperative outcomes and branch patency following open thoracoabdominal aortic replacement in a large institutional cohort. All patients undergoing open branched thoracoabdominal aortic replacement at a single academic center from 2006 to 2020 were included and classified as CTD or non-CTD based on the presence of genotypic documentation. Outcomes were compared using analysis of variance and χ2 testing for continuous and discrete variables, respectively. Kaplan-Meier curves were utilized to examine patency of graft branches over time. Overall, 172 patients were included, with a mean follow-up of 30.5± 34.9months. CTD was present in 45 patients (26%); specifically, 32 had MFS, five had LDS, and eight had another CTD. Patients with CTDs had more extent II thoracoabdominal aneurysms (40% vs 15%), more reconstructed branches (3.5 vs 1.8), more frequently reconstructed visceral branches (86.7% vs 22.7%), and higher intraoperative blood loss (13.3 vs 6.8L; all P< .05) compared with non-CTD patients. Patients with MFS were more frequently systemically anticoagulated preoperatively (50% vs 5%) and demonstrated higher rates of postoperative deep vein thrombosis/pulmonary embolism compared with non-CTD patients (9%vs 2%; both P< .05). Five-year renal branch patency was decreased among all patients compared with visceral branches (87.3% vs 95.6%; P= .05), but there were no individual branch patency differences between patients with and without CTDs (P= .086). Overall branch patency at 1 and 5years was significantly higher in patients with MFS than in non-CTD patients (98.9% vs 89.1% at 5years); there were no significant patency differences between non-CTD patients and any other CTD subgroup, mostly due to early patency loss. Open thoracoabdominal reconstruction in patients with CTD is technically challenging and associated with increased transfusion and postoperative thromboembolic events when compared with non-CTD patients. Technical outcomes of the procedure are excellent and are differentially associated with genotype, with patients with MFS experiencing significantly improved branch patency over both non-CTD patients and patients with other CTDs, a finding which has multifactorial drivers.

Fighting spinal cord complication during surgery for thoracoabdominal aortic disease

Paraplegia or paraparesis after otherwise successful thoracic or thoracoabdominal aortic reconstruction is a devastating complication for both patient and physician. Various strategies have been developed to minimize the incidence of neurological complications after aortic surgery. The incidence of spinal cord ischemia and subsequent neurological complications has been correlated with (1) the duration and severity of ischemia, (2) failure to establish a spinal cord blood supply, and (3) reperfusion injury. Preoperative identification of the arteria radicularis magna, the artery of Adamkiewicz, facilitates identification of critical intercostal vessels for reimplantation, resulting in reestablishing spinal cord blood flow. Techniques for monitoring spinal cord function using evoked potentials have been developed, and surgical techniques have evolved to reduce the duration of ischemia. Furthermore, sequentially sacrificing all the intercostal arteries while maintaining collateral circulation to the cord has produced good outcomes. The severity of ischemia can be minimized by using cerebrospinal fluid drainage, hypothermia, distal bypass, managing the blood pressure, and adjunctive pharmacological therapy. Reperfusion injury can be reduced with the use of antioxidant therapy. Recent advances in endovascular stentgrafting have reduced the incidence of postoperative spinal complications, especially among high-risk patients.

Thoracoabdominal Aortic Aneurysm Repair: Historical Review and Description of a Re-engineered Technique

Most complications related to thoracoabdominal aortic reconstruction stem from ischemia-induced injury to the viscera, kidneys, and spinal cord. Pioneers in the treatment of thoracoabdominal aortic aneurysms recognized the danger of producing ischemic damage to these vital organs. In addition to adjunctive methods designed to minimize metabolic demands of the spinal cord during aortic cross-clamping, a variety of extracorporeal techniques have been developed that provide supplemental blood flow to vital end organs during the period of clamp-induced ischemia. This article reviews these extracorporeal methods and provides a historical perspective of thoracoabdominal aortic aneurysm repair. In addition, a reengineered technique for thoracoabdominal aortic aneurysm repair is highlighted.

Case 3—2005 Risk and Benefits of Cerebrospinal Fluid Drainage During Thoracoabdominal Aortic Aneurysm Surgery

Repair of descending thoracic and thoracoabdominal aortic aneurysms (TAAAs) is associated with a substantial risk of perioperative spinal cord ischemia that may or may not lead to permanent postoperative paralysis. Several techniques that aim to increase the ischemia tolerance time of the spinal cord during the period of aortic cross-clamping have been described in the literature. 1 Afifi S. Cerebrospinal fluid drainage protects the spinal cord during thoracoabdominal aortic reconstruction surgery. J Cardiothorac Vasc Anesth. 2002; 16: 643-649 Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar Hypothermia, left heart bypass, various shunts, myriad drugs, and cerebrospinal fluid (CSF) drainage have all been used alone or in combination to potentially improve neurologic outcome after surgery. CSF drainage and distal aortic perfusion have been shown to lower the incidence of neurologic complications after repair of type I and type II TAAAs. 2 Coselli J. Cerebrospinal fluid drainage reduces paraplegia after thoracoabdominal aortic aneurysm repair Results of a randomized clinical trial. J Vasc Surg. 2002; 35: 631-639 Abstract Full Text Full Text PDF PubMed Scopus (527) Google Scholar Distal aortic perfusion increases distal aortic pressure, and CSF drainage decreases CSF pressure. These techniques potentially lead to an augmentation of spinal cord perfusion pressure during the period of aortic cross-clamping. However, CSF drainage can be associated with potentially serious complications, including fracture of the catheter during removal, catheter-associated meningitis, and/or temporary abducens nerve palsy, among others. 3 Cheung A.T. Pochettino A. Guvakov D.V. et al. Safety of lumbar drains in thoracic aortic operations performed with extracorporeal circulation. Ann Thorac Surg. 2003; 76: 1190-1197 Abstract Full Text Full Text PDF PubMed Scopus (76) Google Scholar Also, epidural hematoma at the catheter insertion site can complicate the clinical assessment of postoperative spinal ischemic injury. 4 Weaver K. Weisman D.B. Farber M. et al. Complications of lumbar drainage after thoracoabdominal aortic aneurysm repair. J Vasc Surg. 2001; 34: 623-627 Abstract Full Text Full Text PDF PubMed Scopus (78) Google Scholar Intracranial subdural hematomas, with excessive CSF drainage, have also been reported and are associated with significant morbidity and mortality. 5 Dardik A. Perler B.A. Roseborough G.S. et al. Subdural hematoma after thoracoabdominal aortic aneurysm repair An underreported complication of spinal fluid drainage?. J Vasc Surg. 2002; 36: 47-50 Abstract Full Text PDF PubMed Scopus (122) Google Scholar Subsequently, some authors have challenged the efficacy of CSF drainage and question the acceptable risk:benefit ratio of the technique. 6 Wallace L. Cerebrospinal fluid drainage does not protect the spinal cord during thoracoabdominal aortic reconstruction surgery. J Cardiothorac Vasc Anesth. 2002; 16: 650-652 Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar , 7 Ling E. Arellano R. Systematic overview of the evidence supporting the use of cerebrospinal fluid drainage in thoracoabdominal aneurysm surgery for prevention of paraplegia. Anesthesiology. 2000; 93: 1115-1122 Crossref PubMed Scopus (48) Google Scholar

Risk of Spinal Cord Injury After Operations of Recurrent Aneurysms of the Descending Aorta

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. 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. 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. 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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INVITED COMMENTARY

Poly(adenosine diphosphate ribose) polymerase inhibition modulates spinal cord dysfunction after thoracoabdominal aortic ischemia-reperfusion

Spinal cord injury (SCI) remains a source of morbidity after thoracoabdominal aortic reconstruction. These studies were designed to determine whether PJ34, a novel ultrapotent inhibitor of the nuclear enzyme poly(adenosine diphosphate ribose) polymerase (PARP) could modulate neurologic injury after thoracic aortic ischemia reperfusion (TAR) in a murine model of SCI. Forty-one anesthetized male mice were subject to thoracic aortic occlusion (11 minutes) through a cervical mediastinotomy followed by 48 hours of reperfusion (TAR) under normothermic conditions. PJ34-treated mice (PJ, n = 12) were given 10 mg/kg PJ34 intraperitoneally 1 hour before ischemia and 1 hour after unclamping. The control group (UN, n = 21) received normal saline intraperitoneally 1 hour before ischemia and 1 hour after unclamping. Sham animals (n = 10) were subject to thoracic aortic exposure with no aortic clamping and similar intraperitoneal normal saline injections. PARP-1-/- (KO, n = 8) mice were subjected to the same conditions as the UN mice. Blinded observers rated murine neurologic status after TAR by using an established rodent paralysis scoring system. Murine spinal cords were subjected to cytokine (GRO-1) protein analysis as a marker of inflammation and immunohistochemical analysis (hematoxylin-eosin and PAR staining). Paralysis scores (PS) and GRO-1 levels were compared with analysis of variance, and survival data were compared with chi 2 . Immediately after TAR, UN and PJ mice had severe neurologic dysfunction (PS = 5.8 +/- 0.1 and 4.6 +/- 0.6, respectively; P > .05), which was significantly worse than the KO mice (PS = 1.0 +/- 0.7, P < .001). After 6, 24, and 48 hours KO mice had no discernable neurologic injury (PS = 0). Six hours after TAR, PJ mice significantly improved (PS = 1.1 +/- 0.73, P < .001) and remained improved at 24 (PS = 0.7 +/- 0.6) and 48 hours (PS = 0.6 +/- 0.6). UN mice did not improve their PS, and Sham mice showed no neurologic abnormality at any time during these experiments. The mortality at 48 hours was 0% for PJ and KO mice, 43% for UN (P = .012), and 0% for Sham. GRO-1 levels were significantly decreased in PJ and KO versus UN mice (UN, 583 +/- 119 vs PJ, 5.8 +/- 0 vs KO, 5.3 +/- 1.4 mg/pg; P < .0001). Immunohistochemistry showed evidence of decreased PAR staining and ventral motor neuron injury in PJ mice. Genetic deletion of PARP or inhibition of its activity (PJ34) rescued neurologic function in mice subjected to TAR. PARP inhibition might represent a novel therapeutic approach for prevention of SCI after TAR.

Delayed paraplegia after thoracic and thoracoabdominal aneurysm repair: a continuing risk

BackgroundParaplegia or paraparesis after otherwise successful thoracic or thoracoabdominal aortic reconstruction is a devastating complication for patient and physician. Interventions for its prevention have focused primarily on the intraoperative period. We have recently noted a significant incidence of delayed-onset neurologic deficit. MethodsWe reviewed our most recent 5-year experience with thoracic and thoracoabdominal reconstruction to examine the incidence of and potential contributors to delayed paraplegia or paraparesis. ResultsBetween June 1996 and June 2001, 60 patients (29 men, 31 women) underwent repair of isolated thoracic (n = 26) or thoracoabdominal aortic aneurysm (Crawford I, n = 7; Crawford II, n = 14; Crawford III, n = 12; Crawford IV, n = 1) by the cardiac and vascular surgical services collaboratively. Repair was performed endovascularly in 6, and open with either circulatory arrest in 12, partial left heart bypass in 37, or partial femorofemoral bypass in 5. Operative mortality was 9.3% (5 of 54 patients) for open repair and 0% for endovascular repair. Paraplegia or paraparesis occurred in 6 (10%) patients of which 83.3% (5 of 6) were delayed in onset. All patients with delayed paraplegia or paraparesis had degenerative aneurysms of Crawford extent II (n = 3) or III (n = 2), had intraoperative left heart bypass, and had perioperative spinal drainage. Delayed paraplegia or paraparesis occurred up to 27 days postoperatively, and was associated with a documented episode of hypotension in 60% (3 of 5) of patients. ConclusionsImprovements in intraoperative management may have reduced immediate paraplegia or paraparesis among vulnerable patients only to leave them at risk of delayed-onset deficit. Postoperative care, including assiduous attention to avoidance of even transient hypotension, must be tailored to this patient population.

Con: Cerebrospinal fluid drainage does not protect the spinal cord during thoracoabdominal aortic reconstruction surgery

PARAPLEGIA RESULTING from ischemic spinal cord injury is the most feared complication associated with thoracoabdominal aortic aneurysm (TAAA) repair. This unpredictable complication is associated with decreased survival and devastating physical disability.1,2 The incidence of permanent or transient paraplegia or paraparesis after aortic aneurysm repair was reported in the early 1990s by Svensson et al1 to range from 4% for type IV TAAAs to 31% for type II TAAAs. Factors associated with postoperative paraplegia or paraparesis include aneurysm extent, acute dissection, rupture, previous aortic surgery, aortic cross-clamp time, diabetes, and preoperative renal dysfunction.

Pro: Cerebrospinal fluid drainage protects the spinal cord during thoracoabdominal aortic reconstruction surgery

Pro: Cerebrospinal fluid drainage protects the spinal cord during thoracoabdominal aortic reconstruction surgery

Type III and IV thoracoabdominal aortic aneurysm repair: Results of a trifurcated/two-graft technique

Objective: Thoracoabdominal aortic aneurysm (TAA) repair continues to present a surgical challenge because of obligate intraoperative visceral, renal, and spinal cord ischemia. A novel two-graft technique with a trifurcated graft for sequential visceral revascularization followed by a second graft for inline aneurysm reconstruction minimizes this endorgan ischemia. We herein present our updated experience with this approach for repair of type III and type IV TAAs. Methods: Thirty-two patients (mean age, 70 years) underwent nonemergent repair of extent III (12 patients) and IV (20 patients) TAAs between March 1996 and October 2001. Repair was achieved with a trifurcated graft for uninvolved descending thoracic aorta-to-celiac/superior mesenteric/renal artery bypass with an additional tube or bifurcated graft for inline aneurysm reconstruction. Adjunctive cerebrospinal fluid drainage was used in the last six patients. Six patients had a solitary kidney, and six had previous infrarenal abdominal aortic aneurysm repair. Results: Mean visceral ischemia times were as follows: celiac artery, 12 minutes; superior mesenteric artery, 12 minutes; left renal artery, 10 minutes; and right renal artery, 33 minutes. The creatinine level at discharge was not significantly different from the preoperative level (1.7 versus 1.3; P = .10). Two patients (6.3%) had transient renal failure; however, the permanent renal failure rate was zero. No patient with a solitary kidney had renal dysfunction develop. Paraplegia occurred in two patients (6.3%), one of whom had prior abdominal aortic aneurysm repair and neither of whom had cerebrospinal fluid drainage. Prolonged ventilatory support (>2 days) was necessitated in six patients (19%). The perioperative mortality rate was 6.3% (two patients). The mean follow-up period was 22 months, with a life-table survival rate of 76% at 36 months. Maintenance of preoperative functional status was achieved in 92% (23/25 patients) of long-term survivors. Conclusion: Type III and IVTAA repair with a trifurcated graft for sequential visceral revascularization followed by a second graft for inline aneurysm reconstruction provides short visceral, renal, and spinal cord ischemia times and leads to low rates of endorgan ischemic damage and paraplegia. Preoperative functional status is maintained in most survivors. These results compare favorably with other methods of TAA repair, and this technique presents a useful option in thoracoabdominal aortic reconstruction. (J Vasc Surg 2002;36:211-6.)

Extracorporeal techniques in thoracoabdominal aortic surgery.

Most complications related to thoracoabdominal aortic reconstruction stem from ischemia-induced injury to the viscera, kidneys, and spinal cord. In addition to adjunctive methods designed to minimize metabolic demands of the spinal cord during aortic cross-clamping, a variety of extracorporeal techniques have been developed that provide supplemental blood flow to vital end organs during the period of clamp-induced ischemia. These techniques represent a broad range of design complexities and command significant operator expertise to optimize their benefit. This section briefly describes commonly used extracorporeal circulation methods in thoracoabdominal aortic surgery.

Naloxone infusion and drainage of cerebrospinal fluid as adjuncts to postoperative care after repair of thoracoabdominal aneurysms

The mechanisms that produce paraplegia in patients after TAA repair are complex and involve alterations in regional blood flow to the spinal cord, CSF dynamics, and reperfusion. Although neither the minimal level of blood flow nor the maximal spinal cord pressure that can be tolerated by the spinal cord is known, adjuncts such as CSF drainage and naloxone infusions may allow longer durations of aortic cross-clamping before irreversible ischemia occurs. Because paraplegia is multifactorial and none of the recommended adjuncts alone provides complete protection of the spinal cord, a combination of treatments may be necessary to reduce the prevalence of neurological complications after thoracoabdominal aortic reconstruction. Critical care nurses thus must be acquainted with the advanced monitoring techniques and the pathophysiology behind these new treatment modalities. Advanced assessment skills are also essential to recognize the potential neurological complications that may occur in these patients. Care of patients with TAA is a challenge. Critical care nurses must use multidimensional skills in the areas of hemodynamic monitoring, physical assessment, and psychological counseling to effectively manage postoperative care of these patients.

Aortic Reconstruction in Kidney Transplant Recipients

Renal transplantation has increased the longevity of patients with uremia. An increasing number undergo aortic reconstruction, which exposes the transplanted kidney to ischemic injury. To evaluate the risk for renal failure, loss of the transplant, and methods of renal protection, we reviewed our experience. Clinical data were reviewed for 10 consecutive patients (7 men, 3 women; mean age 52.7 years [range 32 to 75 years]) with a transplanted kidney who underwent aortic reconstruction between 1977 and 1994 at our institution. Mean interval between renal transplantation and aortic reconstruction was 5.9 years (range 1 month to 12.7 years). Seven patients required emergency repair because of dissection (2 patients), aneurysm rupture (4 patients), or symptomatic aneurysm (1 patient); three underwent elective repair. Reasons for reconstruction included aortic dissection (2 patients), aneurysm of the descending thoracic (2 patients), thoracoabdominal (1 patient), or abdominal aorta (3 patients), and aortoiliac occlusive disease (2 patients). Patients with thoracic or thoracoabdominal reconstructions underwent repair with atriofemoral, aortofemoral, or femorofemoral shunt placement or bypass. Of the five abdominal aortic reconstructions, the kidney was protected with aortofemoral shunt placement in one patient and cold renal perfusion in three. In two of them, topical cooling of the kidney also was used. One patient with acute aortic dissection died at 39 days as a result of respiratory failure. Loss of the recently transplanted kidney was caused by acute rejection. One patient had a transient increase in serum creatinine concentration. Eight no worsening of renal function, and none of the nine survivors lost the transplanted kidney. We concluded that aortic reconstruction can be safely performed in kidney transplant recipients. Patients in whom thoracic or thoracoabdominal aortic reconstruction was required were protected with an atriofemoral or aortofemoral bypass or shunt. Patients undergoing abdominal aortic reconstruction did well when cold renal perfusion with or without local cooling of the transplant was used for renal protection. Transplanted kidneys appeared to tolerate ischemic injury similarly to native kidneys.

Complex abdominal and thoracoabdominal aortic aneurysm reconstruction

Complex reconstructions of the abdominal aorta are required for aneurysms that require visceral or splanchnic revascularization, when the aorta is inflammatory or infected, when a fistula to the vena cava or bowel is present, and when the aneurysm involves the juxtarenal, pararenal segments, or the full length of the abdominal aorta. The technique for full-length abdominal and thoracoabdominal aortic reconstructions has been modified to separate the visceral and spinal cord revascularization from the body of the main graft. The visceral, renal, and intercostal arteries are not directly reimplanted into the aortic graft but rather into sidearm grafts using a patch inclusion technique. The reconstruction commences distally by anastomosing the main graft to the aortic bifurcation or to the iliac arteries as appropriate. The main graft is then anastomosed to the proximal aorta after which the aortic clamps are released to perfuse the lower limbs. The intercostal arteries are reimplanted into a posterior sidearm graft followed by visceral and renal artery reimplantation into an anterior sidearm graft. This technique reimplantation into an anterior sidearm graft. This technique reduces the period of left ventricular strain to the time taken to complete the upper aortic anastomosis. It also allows separate control of the visceral and intercostal implantations should bleeding occur, without the necessity to reclamp the main body of the graft.

Spinal evoked potential in patients undergoing thoracoabdominal aortic reconstruction: a prognostic indicator of postoperative motor deficit.

We studied 76 patients who had thoracoabdominal aortic reconstruction between January 1981 and March 1991. Evoked potential monitoring of the spinal cord (peridural bipolar catheter stimulation at level L4-L5, recording via a second bipolar catheter at level Th4) was used to predict intraoperatively a possible motor deficit. There was a close linear correlation of r = 0.892 between postoperative motor deficit (normal, paraparesis, paraplegia) and the time from declamping to reappearance of the potential. Forty-three of 76 patients received prostaglandin E1 (5 ng/kg/min) for pharmacologic protection of the spinal cord 15 minutes before onset of clamping and through the entire clamping period. Patients with protection had a loss of their potential significantly later (20.2 min; p < 0.05) than those patients who had not received any pharmacologic treatment (15.2 min). Pharmacologic protection also resulted in a reduced incidence of postoperative neurologic deficit and paraplegia when compared with patients receiving no treatment (25% vs 5%). These data suggest that spinal evoked potentials may be very useful for monitoring during these hazardous cases. They also suggest that pharmacologic protection before clamping may help preserve the function of the spinal cord during aortic clamping.

Spinal cord injury in experimental thoracic aortic occlusion: Investigation of combined methods of protection

The efficacy of combined methods of spinal cord protection during thoracoabdominal aortic reconstruction was evaluated because a recent clinical study failed to substantiate the value of cerebrospinal fluid drainage when used alone in the prevention of paraplegia. The effect of cerebrospinal fluid drainage and aortofemoral shunting were analyzed with regard to neurologic outcome and spinal cord blood flow in a model of thoracic aortic occlusion. In addition, we studied the use of motor-evoked potentials as compared with somatosensory-evoked potentials in monitoring cord perfusion. Thirty-two dogs underwent proximal and distal thoracic aortic occlusion for 60 minutes. The control group (n = 8) underwent thoracic aortic cross-clamping only. Spinal cord protection was used in three groups: cerebrospinal fluid drainage alone (n = 8), aortofemoral shunting alone (n = 8), and cerebrospinal fluid drainage and aortofemoral shunting (n = 8). Neurologic outcome improved in all treatment groups as compared with controls (p < 0.001). The addition of cerebrospinal fluid drainage to aortofemoral shunting did not further improve neurologic outcome. Spinal cord blood flow measured with microspheres in the lumbar gray matter was significantly higher in the dogs with aortofemoral shunting (± cerebrospinal fluid drainage) as compared with those with cerebrospinal fluid drainage alone (p < 0.05) or the controls (p < 0.001). Aortofemoral shunting also prevented the development of acidosis and hyperglycemia. Loss or changes in amplitude and latency of motor-evoked potentials did not distinguish between the groups. Loss of somatosensory-evoked potentials had a high sensitivity (92%) but lower specificity (68%) in predicting neurologic injury, whereas loss of motor-evoked potentials had a high specificity (100%) but a very low sensitivity (16%). We conclude that cerebrospinal fluid drainage or aortofemoral shunting significantly improve spinal cord blood flow and neurologic outcome. The greatest increase in spinal cord blood flow was seen with aortofemoral shunting, which also prevented metabolic disturbances of reperfusion. Although the addition of cerebrospinal fluid drainage to aortofemoral shunting was the only group in which no neurologic injury occurred, this group did not have a significant improvement in outcome when compared with aortofemoral shunting alone. Spinal cord ischemia was more accurately detected with somatosensory-evoked potentials when aortofemoral shunting was used, whereas motor-evoked potentials recorded from the spinal cord were not sensitive enough to predict neurologic injury.