Spinal cord protection during surgical procedures on the descending thoracic and thoracoabdominal aorta: a critical overview

Two episodes of remote ischemia preconditioning improve motor and sensory function of hind limbs after spinal cord ischemic injury

Objectives: To investigate the effect of one and two remote ischemia preconditioning episodes (1-RIPC or 2-RIPC, respectively) on neuro-protection after spinal cord ischemic injury (SCI) in rats. Design: Experimental animal study. Setting: College of Medicine, King Khalid University, Abha, KSA. Interventions: Male rats (n = 10/group) were divided into control, sham, SCIRI, 1-RIPC + SCIRI, and 2-RIPC + SCIRI. SCI was induced by aortic ligation for 45 min and each RIPC episode was induced by 3 cycles of 10 min ischemia/10 min perfusion. The two preconditioning procedures were separated by 24 h. Outcome measures: after 48 h of RIPC procedure, Tarlov's test, withdrawal from the painful stimulus and placing/stepping reflex (SPR) were used to evaluate the hind limbs neurological function. SC homogenates were used to measure various biochemical parameters. Results: Motor and sensory function of hind limbs were significantly improved and levels of MDA, AOPPs, PGE2, TNF-α, and IL-6, as well as the activity of SOD, was significantly decreased in SC tissue in either 1 or 2 episodes of RIPC intervention. Concomitantly, levels of total nitrate/nitrite and eNOS activity were significantly increased in both groups. Interestingly, except for activity of SOD, eNOS and levels of nitrate/nitrite, the improvements in all neurological biochemical endpoint were more profound in 2-RIPC + SCIRI compared with 1-RIPC + SCIRI. Conclusion: applying two preconditioning episodes of 3 cycles of 10 min ischemia/10 min perfusion, separated by 24 h, boost the neuro-protection effect of RIPC maneuver in rats after ischemic induced SCI in rats.

Which type of conditioning method protects the spinal cord from the ischemia–reperfusion injury in 24 hours?

Objective

This study was designed to test the effects of different types of preconditioning and postconditioning methods on spinal cord protection following aortic clamping.

Methods

The animals (rabbits) were divided into sham-operated, ischemic preconditioning, remote ischemic preconditioning, simultaneous aortic and ischemic remote preconditioning, and ischemic postconditioning groups. After neurological evaluations, ultrastructural analysis and immunohistochemical staining for caspase-3 were evaluated after 24 h following ischemia.

Results

The neurological outcomes of the remote ischemic preconditioning (4.2 ± 0.4) and ischemic postconditioning (4.6 ± 0.8) groups were significantly improved when compared with the ischemia group (2.2 ± 04). The immunohistochemical analysis revealed that the lowest percentage of apoptosis was in-group ischemic preconditioning at 12.5 ± 30.6%. In the comparison of intracellular edema in an ultrastructural analysis, the ischemic preconditioning and ischemic postconditioning groups had significantly lower values than the ischemia group.

Conclusion

The conditioning methods attenuate ischemia–reperfusion injury for spinal cord injury. Ischemic and remote preconditioning and also postconditioning methods are simple to perform and inexpensive.

Rat model of spinal cord injury preserving dura mater integrity and allowing measurements of cerebrospinal fluid pressure and spinal cord blood flow

PURPOSES

Cerebrospinal fluid (CSF) pressure elevation may worsen spinal cord ischaemia after spinal cord injury (SCI). We developed a rat model to investigate relationships between CSF pressure and spinal cord blood flow (SCBF).

METHODS

Male Wistar rats had SCI induced at Th10 (n = 7) or a sham operation (n = 10). SCBF was measured using laser-Doppler and CSF pressure via a sacral catheter. Dural integrity was assessed using subdural methylene-blue injection (n = 5) and myelography (n = 5).

RESULTS

The SCI group had significantly lower SCBF (p < 0.0001) and higher CSF pressure (p < 0.0001) values compared to the sham-operated group. Sixty minutes after SCI or sham operation, CSF pressure was 8.6 ± 0.4 mmHg in the SCI group versus 5.5 ± 0.5 mmHg in the sham-operated group. No dural tears were found after SCI.

CONCLUSION

Our rat model allows SCBF and CSF pressure measurements after induced SCI. After SCI, CSF pressure significantly increases.

Blood supply and vascular reactivity of the spinal cord under normal and pathological conditions

The authors present a review of spinal cord blood supply, discussing the anatomy of the vascular system and physiological aspects of blood flow regulation in normal and injured spinal cords. Unique anatomical functional properties of vessels and blood supply determine the susceptibility of the spinal cord to damage, especially ischemia. Spinal cord injury (SCI), for example, complicating thoracoabdominal aortic aneurysm repair is associated with ischemic trauma. The rate of this devastating complication has been decreased significantly by instituting physiological methods of protection. Traumatic SCI causes complex changes in spinal cord blood flow, which are closely related to the severity of injury. Manipulating physiological parameters such as mean arterial blood pressure and intrathecal pressure may be beneficial for patients with an SCI. Studying the physiopathological processes of the spinal cord under vascular compromise remains challenging because of its central role in almost all of the body's hemodynamic and neurofunctional processes.

Delayed response of transcranial myogenic motor-evoked potential monitoring to spinal cord ischemia during repair surgery for descending thoracic aortic aneurysm

The efficacy of transcranial myogenic motor-evoked potential (tc-MEP) monitoring during thoracic aortic surgery has been the subject of some reports, because tc-MEP monitoring can rapidly reflect changes in spinal cord blood flow during thoracic aortic cross-clamping. In this article, we present a case in which delayed loss of tc-MEP signals was observed after cross-clamping of the descending thoracic aorta. We must be aware that tc-MEPs recorded from the lower extremities can fail to provide rapid detection of spinal cord ischemia in the upper thoracic level after cross-clamping of the descending thoracic aorta.

Transcranial motor-evoked potentials monitoring can detect spinal cord ischemia more rapidly than spinal cord-evoked potentials monitoring during aortic occlusion in rats

In this study, we evaluated the efficacy of transcranial motor-evoked potentials (tc-MEPs), compared with segmental spinal cord-evoked potentials (SCEPs), for detecting spinal cord ischemia (SCI) and assessed the relationship between neurological outcome and tc-MEPs or SCEPs in the rat aortic occlusion model. In the rats, SCI was induced by aortic occlusion for 10 min with a balloon catheter. At first, tc-MEPs (Group A: n = 6) or segmental SCEPs (Group B: n = 6) was recorded during SCI. Second, in using the quantal bioassay for the relationship between an interval of aortic occlusion and the probability of positive response in tc-MEPs or segmental SCEPs, the P50(MEP) and P50(SCEP) which represent the interval of aortic occlusion associated with 50% probability of assessment of ischemic spinal cord dysfunction by tc-MEP and SCEP were analyzed. The amplitude of tc-MEPs decreased significantly at 30 s and disappeared completely at 2 min after aortic occlusion. In Group B, it took about 6 min after aortic occlusion to diminish SCEP signal amplitude by approximately 50%. P50(MEP) obtained in the quantal analysis was 0.3 +/- 0.1 min. P50(SCEP) was calculated as 6.2 +/- 0.5 min that was significantly (P < 0.01) longer than P50(MEP). Our data indicated that tc-MEP monitoring could detect the onset of SCI so rapidly in comparison with segmental SCEP monitoring, which could provide therapeutic windows in a surgical approach that includes spinal cord protection.

Change pattern of somatosensory-evoked potentials after occlusion of segmental vessels: possible indicator for spinal cord ischemia

Paraplegia was reported after occlusion of the segmental vessels during anterior spinal surgery. The aim of this study was to investigate the effect of occlusion of the segmental vessels on the somatosensory-evoked potential (SEP) monitoring and analyze its potential risk for cord ischemia. Thirty-one patients with thoracic scoliosis underwent anterior spinal surgery. T5-T11 segmental vessels on the convexity were occluded with microvascular clamps at the point 2 cm from the intravertebra foramen. The SEPs were recorded 5 min before occlusion and 2, 7, 12 and 17 min after occlusion. The SEPs were analyzed with two indices i.e. P40 latency and P40 amplitude. All SEP waveforms recorded during the test were regular and recognizable. Compared to 5 min before occlusion, the P40 latencies at 2 min and 7 min after occlusion significantly increased 3.39% and 2.76% on an average, the P40 amplitudes at 2 min after occlusion significantly declined 26% (peak to peak) or 22% (peak to baseline) on an average (P<0.05). But the changes of SEPs were temporary. The SEPs began to restore at 12 min after occlusion and returned to the pre-occlusion level at 17 min after occlusion. No neurologic complications occurred in all patients after surgery. These results suggest that SEP is a possible indicator for ischemia of the spinal cord which is a dynamic course and cannot be considered an "all-or-none" phenomenon. Without the factors such as developmental deformities of the spinal cord, vascular variation and potential cord ischemia, occlusion of the segmental vessels would be safe during the anterior spinal surgery.

The evolution of ischemic spinal cord injury in function, cytoarchitecture, and inflammation and the effects of adenosine A2A receptor activation

OBJECTIVE

Spinal cord ischemia/reperfusion injury involves multiple factors that may be modulated by adenosine A 2A receptor activation. This study defines injury progression in terms of function, cytoarchitecture, and inflammation and assesses whether adenosine A 2A receptor activation by ATL-146e limits injury progression.

METHODS

Mature swine were divided into 3 groups: sham thoracotomy, IR (30 minutes of ischemia followed by reperfusion), and ATL (ischemia/reperfusion with ATL-146e administration for the first 3 hours of reperfusion). Subgroups were killed at 0, 3, 6, 12, 24, and 48 hours after reperfusion. Function was followed up with Tarlov scores. Spinal cord tissue was evaluated for neuronal viability, microtubule-associated protein-2 immunohistochemistry, and neutrophil sequestration (myeloperoxidase assay). Spinal cord tissue, cerebrospinal fluid, and serum were evaluated for tumor necrosis factor-alpha by enzyme-linked immunosorbent assay.

RESULTS

Function was significantly impaired at 24, 36, and 48 hours in the IR group compared with the sham and ATL groups ( P < .05). Neuronal viability and microtubule-associated protein-2 staining were significantly preserved in the sham and ATL groups compared with the IR group at 24 and 48 hours ( P < .05). Spinal cord myeloperoxidase levels were significantly higher in the IR group than in the sham and ATL groups at 24 and 48 hours. Although negligible in serum and cerebrospinal fluid, tumor necrosis factor-alpha levels in the spinal cord peaked significantly higher in the IR group compared with the sham and ATL groups at 6 and 24 hours ( P < .05).

CONCLUSIONS

Spinal cord ischemia/reperfusion induced changes in neutrophil sequestration, microtubule-associated protein-2 expression, and neuronal viability within 24 hours of reperfusion. Spinal cord tumor necrosis factor-alpha increased significantly by 6 to 12 hours after reperfusion. Adenosine A 2A receptor activation attenuates spinal cord inflammation, which may be critical for the preservation of neuronal function and cytoarchitecture after ischemia/reperfusion.

The use of left heart bypass in the repair of thoracoabdominal aortic aneurysms: current techniques and results

The surgical repair of thoracoabdominal aortic aneurysms (TAAA) remains challenging. The prevention of spinal cord ischemic complications requires a multidisciplinary approach. The protective effect of left heart bypass (LHB), particularly regarding spinal cord ischemia, during the repair of extensive TAAA is evaluated here. Data from 1,250 consecutive patients who underwent the repair of extent I or extent II TAAA over a 16-year period was prospectively entered into a database. LHB was used in 666 (53.3%) patients. This group was retrospectively compared with 584 (46.7%) patients who had undergone surgery without the use of LHB. A total of 1,173 (93.8%) patients were 30-day survivors. Paraplegia or paraparesis developed postoperatively in 68 (5.5%) patients. In patients with extent I TAAA, paraplegia and paraparesis rates in the LHB cohort (9 of 290, 3.1%) and those without LHB (13 of 313, 4.2%) were statistically similar (P=0.866). The latter was observed despite the fact that longer clamp times were used in the LHB group. In patients with extent II TAAA, the LHB group had a statistically significant lower incidence of paraplegia or paraparesis (17 of 375, 4.5%) compared with the non-LHB group (29 of 259, 11.2%; P=0.019). In our experience, we identified LHB as protective for reducing the risk of postoperative paraplegia and paraparesis in patients who underwent the repair of extent I and extent II TAAA, the latter statistically significant.

The role of pharmacology in spinal cord protection during thoracic aortic reconstruction

Surgery of the thoracic aorta continues to have a significant risk of neurologic complication. Several strategies to minimize this risk are emerging. Pharmacologic protection from these complications continues to be researched, but at this point few medications are being used clinically. This article reviews the pathophysiology of ischemic spinal cord injury and summarizes the investigational pharmacology that may prevent these serious complications.

Neuroprotective synergy of N-methyl-D-aspartate receptor antagonist (MK801) and protein synthesis inhibitor (cycloheximide) on spinal cord ischemia-reperfusion injury in rats

Thoraco-abdominal aortic surgery requiring temporal cross clamping of the aorta results in a high incidence of paraplegia due to temporary ischemia of the spinal cord. Both excitotoxicity and apoptosis are implicated in the pathogenesis of spinal cord ischemia-reperfusion injury. We propose that the N-methyl-D-aspartate receptor antagonist dizocilpine maleate (MK801) and the protein synthesis inhibitor cycloheximide produce a synergic effect in a rodent model of spinal cord ischemia-reperfusion injury. Injury was induced by 20 min of temporal thoracic aorta occlusion and distal blood volume reduction. After injury, the animals were treated with vehicle, MK801, cycloheximide or MK801 and cycloheximide. Hind limb motor function recovery was better in the MK801 and combined therapy groups than in the control and cycloheximide groups. The mean neuronal survival rate of the control group was 45.3 +/- 3.2% on the 7(th) day after injury. In the MK801 and cycloheximide treatment groups, neuronal survival increased to 62.4 +/- 3.6% and 54.1 +/- 2.4%, respectively. For the combined therapy group, neuronal survival increased to 75.6 +/- 2.5%. The number of apoptotic cells in the control group was 211.4 +/- 8.8 per section on the 7th day after ischemic insult, while apoptosis was significantly reduced in the cycloheximide (96.8 +/- 6.7 cells) and combined (84.8 +/- 8.5 cells) groups. It was unchanged in the MK801 group (209.8 +/- 5.4 cells). These results suggest that combined treatments directed at blocking both N-methyl-D-aspartate receptor-mediated excitotoxic necrosis and caspase-mediated apoptosis might have synergic therapeutic potential in reducing spinal cord ischemia-reperfusion injury.

Effects of intrathecal administration of a cell permeant caspase inhibitor, boc-D-fluoromethylketone (BDFMK), on behavioral deficits following spinal cord ischemia: a dose-response analysis

Caspase inhibition has been proposed as a target to attenuate ischemia-induced neurodegeneration and behavioral dysfunction. The present study evaluated the pharmacological effects of a single dose of an irreversible cell permeant general (nonselective) caspase inhibitor, Boc-D-fluoromethylketone (BDFMK) administered intrathecally (i.t.) in a reversible spinal cord ischemia model (RSCIM). Quantal analysis indicated that the P(50) (represents the duration of ischemia that produces permanent paraplegia in 50% of the animals in a group) of the control group was 25.08+/-4.71 min. Using the RSCIM, neuroprotection is observed if a drug significantly prolongs the P(50) compared to the control group. The P(50) values for the BDFMK-treated groups were 27.21+/-2.62, 27.28+/-3.29 and 28.98+/-2.32 min, for the three dose groups studied. There were no statistically significant changes when measured 18 or 48 h following ischemia. Biochemical analysis of cell extracts from the caudal lumbar spinal cord indicated that there was increased production of the 120-kDa fragment of fodrin suggesting enhanced caspase-3 activity, an increase that was reduced by i.t. BDFMK administration. Moreover, in caudal lumbar spinal cord extracts from a set of paraplegic rabbits (25-50 min occlusion), we measured a 32-42% decrease of caspase-3 activity in BDFMK-treated rabbits. The present study shows that i.t. administration of BDFMK reduced caspase-3 activity, but the inhibition did not translate into a significant behavioral improvement. Our results suggest that administration of a single dose of the caspase inhibitor BDFMK is insufficient to attenuate ischemia-induced behavioral deficits following aortic occlusion.

Protective effect of prostaglandin E1 against ischemia of spinal cord during aortic cross clamping

PURPOSE

The purpose of this study was to investigate whether or not 5-minute segmental intraaortic perfusion of prostaglandin E1 (PGE1) in the preischemic period has a protective effect against spinal cord ischemia during aortic cross clamping.

METHODS

The rabbits were divided into two groups. In group A (n = 6), the infrarenal aorta was segmentally cross clamped and the segment was perfused for 5 minutes with blood and saline solution at first. The aorta was kept cross clamped without perfusion for a subsequent 20 minutes. In group B (n = 6), the infrarenal aorta was segmentally cross clamped and the segment was perfused for 5 minutes with blood and saline solution containing PGE1 of 100 ng/kg/min at first. The aorta was kept cross clamped without perfusion for a subsequent 20 minutes. After the aorta was declamped, the experimental animals recovered from the anesthesia. Twenty-four and 48 hours after the operation, the hind limb function was estimated with Tarlov's grade. Then, the animals were killed for pathologic study.

RESULTS

The systolic arterial pressures measured at the left common carotid artery through the experiment were not significantly different between the two groups. The perfusion of the aortic segment between the proximal and distal clamp was nonpulsatile. The perfusion pressures of the aortic segments at 5 minutes after aortic cross clamping were 29 +/- 6 mm Hg and 33 +/- 6 mm Hg in groups A and B, respectively. No significant differences were seen between the two groups. In group A, the hind limb functions evaluated with Tarlov's grade after 24 hours and 48 hours were 0 to 3 (1.5 +/- 1.4) and 0 to 3 (1.3 +/- 1.4), respectively. In group B, these were 3 to 4 (3.5 +/- 0.5) and 3 to 4 (3.7 +/- 0.5), respectively. A significant difference was seen between the two groups (P <.05). In the ventral horn of the L5, L6, and L7 segments, large motor neurons that seemed viable were more preserved in group B than in group A.

CONCLUSION

Segmental intraaortic perfusion of PGE1 in the preischemic period reduced neurologic damage of spinal cord ischemia.

Morphological changes of the anterior spinal artery during aortic cross-clamping and effect of prostaglandin E1 with perfusion

This investigation was designed to evaluate the morphological changes of anterior spinal artery (ASA) and its reaction to prostaglandinE1 (PGE1) during aortic cross-clamping. ASA during 30 min cross-clamping was observed with charge-coupled device (CCD) and ASA diameter (ASAD) was measured. Group A: Infrarenal aorta was cross-clamped. Group B: Infrarenal aorta was cross-clamped and aorta above the bifurcation was snared. The aortic segment between clamp and snare was perfused with blood. Group C: PGE1 of 100 ng/kg/min was added to perfusate of Group B. The aortic segmental pressures in group B and C were about 30% of the proximal systolic arterial pressure and were significantly higher than distal pressure of group A. After cross-clamping, ASAD decreased about 80% of before cross-clamping in group A. By segmental perfusion of which pressure was about 30% of proximal systolic arterial pressure, ASAD remained almost 90% in group B. By administration of PGE1, ASAD was significantly increased in group C. The changes of ASAD were significantly different between group A and C, and between group B and C.

Paraparesis induced by inflammatory contents of a pneumonectomy cavity. Case report

The authors report on a patient who developed acute-onset paraparesis after underoing a thoracotomy 40 years earlier for a carcinoid adenoma. No infectious or neoplastic origin could be found to explain the patient's current clinical course and radiographic findings. The postoperative events in this case are discussed, as well as the literature regarding postthoracotomy complications.

Single-clamp technique for aneurysms of the descending thoracic aorta: report of 132 consecutive cases

OBJECTIVE

To determine the efficacy of a single-clamp technique in preventing spinal cord ischemia during repair of aneurysms of the descending thoracic aorta.

PATIENTS AND METHODS

From January 1989 to May 1999, 132 consecutive patients (91 men and 41 women, aged 31-86 years), with aneurysms of the descending thoracic aorta underwent repair using a single-clamp technique and temporary partial distal exsanguination. The diseased aortic segment was replaced with a Dacron graft. Blood was re-infused from an auto-transfusion device, and the segmental vessels were over-sewn but not implanted into the graft.

RESULTS

The average aortic cross-clamp time was 26.4 min (range, 11-67 min) for the overall group and 37.4 min for patients who had spinal cord complications. An average of 2066 ml of blood was auto-transfused (range, 450-6100 ml). During the first 30 postoperative days, 17 patients (12.9 %) died. Eleven patients (8.3%) had spinal cord dysfunction, six patients (4.5%) had lower-extremity paraparesis, and five patients (3.8%) had paraplegia. Nine patients (6.8%) had renal failure necessitating hemodialysis. Other complications included bleeding in 15 cases (11.4%), respiratory failure in 12 cases (9.1%), wound-related sequelae in five cases (3.8%), distal embolism in five cases (3.8%), and bowel ischemia in two cases (1.5%).

CONCLUSION

The single-clamp technique yielded an acceptable complication rate, and the mortality was comparable to that seen after the use of more complex methods. For satisfactory results, the cross-clamp time should not exceed 30 min.

Femoral artery ischemia during spinal scoliosis surgery detected by posterior tibial nerve somatosensory-evoked potential monitoring

STUDY DESIGN

A case report of unilateral leg ischemia caused by femoral artery compression detected using posterior tibial nerve somatosensory-evoked potentials during spinal scoliosis instrumentation surgery.

OBJECTIVES

To report a rare cause of intraoperative unilateral loss of all posterior tibial nerve somatosensory-evoked potential waveforms.

SUMMARY OF BACKGROUND DATA

Failure to obtain adequate popliteal fossa, spinal, subcortical, and cortical potentials during posterior tibial nerve somatosensory-evoked potential spinal cord monitoring usually results from technical factors or chronic conditions affecting the peripheral nerve.

METHODS

A 16-year-old boy with thoracic scoliosis had normal posterior tibial nerve somatosensory-evoked potentials both before surgery and in the operating room immediately after anesthesia induction and prone positioning on a four-post spinal frame.

RESULTS

One hour after the start of surgery, a minimal amplitude reduction of the right popliteal fossa potentials appeared. Fifteen minutes later, the amplitudes of the popliteal fossa, subcortical, and cortical potentials evoked by right posterior tibial nerve stimulation became substantially reduced. Subsequently, all waveforms were lost. Malfunction of the right posterior tibial nerve stimulator was initially suspected, but when proper function was verified, a search for other causes of this loss led to discovery of leg ischemia. The patient was repositioned on the spinal frame, and all posterior tibial nerve somatosensory-evoked potentials waveforms began to reappear 7 minutes later. There was no postoperative clinically detectable complication.

CONCLUSIONS

Although technical malfunction should always be suspected when all intraoperative somatosensory-evoked potential waveforms are initially seen and subsequently lost, one should also consider the possibility that intraoperative ischemia due to limb positioning could be the etiology.

Comparison of Nikkiso and Bio-Medicus Pumps in Thoracoabdominal Aortic Surgery

Left heart bypass reduces the risk of ischemic complications during the repair of extensive thoracoabdominal aortic aneurysms. This prospective study compared the performance of the recently developed Nikkiso centrifugal pump with the well-established Bio-Medicus pump during left heart bypass for thoracoabdominal aortic aneurysm surgery. Thirty-five consecutive patients undergoing graft repair of extensive thoracoabdominal aortic aneurysms were prospectively assigned to have left heart bypass using either the Bio-Medicus (in the first 19 patients) or Nikkiso pump (in the next 16 patients). There were no significant differences in pump flow rates or patient hemodynamics between the two groups and there was no evidence of pump malfunction. All patients survived and none developed postoperative coagulopathy, myocardial infarction, or left heart failure. Paraparesis developed in 2 patients in the Nikkiso group (12.5%); there were no neurologic complications in the Bio-Medicus group (p = 0.202). One patient in the Bio-Medicus group developed renal failure (5.3%; p = 1.000 vs. Nikkiso group). Overall, no significant differences were found in the incidence of postoperative complications. Although a small series, this comparison demonstrates that the Nikkiso centrifugal pump is as effective and safe in providing left heart bypass during thoracoabdominal aortic aneurysm repair as the widely-used Bio-Medicus model.

Surgical techniques. Thoracoabdominal aorta

Patients presenting with impending rupture of a thoracoabdominal aortic aneurysm require emergency operative repair. To prevent rupture and its associated mortality, elective repair of thoracoabdominal aortic aneurysms exceeding 5.5 cm to 6.0 cm in diameter is recommended in patients with adequate physiologic reserve. Similarly, surgery should be considered for patients with smaller symptomatic aneurysms. Atypical symptoms have been associated with rupture, therefore, they require thorough evaluation. Whether the aortic conditions are caused by medial degenerative disease or chronic aortic dissection, surgical techniques allow for graft repair of thoracoabdominal aortic aneurysms with low mortality and morbidity rates. Although surgery is usually avoided in patients with acute distal aortic dissection, operative intervention is occasionally required when complications develop. Patients with acute aortic dissection complicated by impending rupture of the thoracoabdominal segment require graft repair to restore aortic integrity; although the mortality rate is acceptable, the incidence of postoperative paraplegia approaches 20% in this setting. For patients presenting with ischemic complications of acute distal aortic dissection, less-extensive surgical options have been effective in restoring perfusion. In experienced centers, overall operative survival rate following thoracoabdominal aortic surgery can exceed 92%. Retrospective data suggest that left heart bypass reduces the incidence of paraplegia following extensive thoracoabdominal aortic repairs. Although recent advances have led to improved outcomes, paraplegia continues to occur regardless of the strategy used. The prevention of spinal cord ischemia during thoracoabdominal aortic surgery, therefore, will remain a focus of controversy and investigation, just as it was more than 4 decades ago.

Left heart bypass reduces paraplegia rates after thoracoabdominal aortic aneurysm repair

BACKGROUND

The optimal strategy for spinal cord protection during thoracoabdominal aortic aneurysm (TAAA) repair remains unclear. We evaluated the protective effect of left heart bypass (LHB) during repair of extensive TAAAs.

METHODS

During a 12-year period, 710 patients had repair of extent I or II TAAAs. Left heart bypass was used in 312 (43.9%) patients. This group was retrospectively compared with 398 (56.1%) patients who had operations without LHB.

RESULTS

The overall 30-day survival rate was 94.8% (673 patients). In 42 patients, (6.0%) paraplegia or paraparesis developed. In patients with extent I TAAAs, paraplegia and paraparesis rates in LHB (6 of 123, 4.9%) and non-LHB (9 of 246, 3.7%) groups were similar (p = 0.576) despite longer aortic clamp times in the former group. In patients with extent II TAAAs, the LHB group had a lower incidence of paraplegia or paraparesis (9 of 189, 4.8%) compared with the non-LHB group (18 of 137, 13.1%; p = 0.007).

CONCLUSIONS

Left heart bypass reduced the risk of paraplegia and paraparesis in patients who had repair of extent I and II TAAAs.