Spinal cord protection in the absence of collateral circulation: meta-analysis of mortality and paraplegia

Major vascular traumas to the neck, upper limbs, and chest: Clinical presentation, diagnostic approach, and management strategies

Major vascular traumas to the neck, upper limbs, and chest may arise from penetrating and/or blunt mechanisms, resulting in a range of clinical scenarios. Lesions to the carotid arteries may also lead to neurologic complications, such as stroke. The increasing use of invasive arterial access for diagnostic and/or interventional purposes has increased the rate of iatrogenic injuries, which usually occur in older and hospitalized patients. Bleeding control and restoration of perfusion represent the two main goals of treatment for vascular traumatic lesions. Open surgery still represents the gold standard for most lesions, although endovascular approaches have increasingly emerged as feasible and effective options, particularly for management of subclavian and aortic injuries. In addition to advanced imaging (including ultrasound, contrast-enhanced cross-sectional imaging, and arteriography) and life support measures, multidisciplinary care is required, particularly in the setting of concomitant injuries to the bones, soft tissues, or other vital organs. Modern vascular surgeons should be familiar with the whole armamentarium of open and endovascular techniques needed to manage major vascular traumas safely and promptly.

Preoperative Coil-Embolization of a Large, Myelon-Compressing Vertebral Metastasis Involving the Artery of Adamkiewicz

Background Metastatic spinal cord compression causes neurologic impairment and pain, potentially improved by decompression surgery at the risk of heavy intraoperative bleeding. Preoperative embolization carries the risk of nontarget embolization, potentially causing spinal ischemia. Current evidence indicates that knowledge of artery of Adamkiewicz (AKA) location and the amount of collateralization may help estimate the risk of postinterventional spinal cord injury.

Case Presentation In this case of a 73-year-old female patient with progression of a large, myelon-compressing vertebral metastasis of L1, protective, blood-flow-controlling occlusion of the proximal-most points of the AKA and segmental spinal arteries was safely performed prior to tumor embolization, surgical decompression, and tumor debulking.

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA): Zone I Balloon Occlusion Time Affects Spinal Cord Injury in the Nonhuman Primate Model

OBJECTIVES

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) has been used clinically to limit torso bleeding and restore central perfusion. The objective of this study was to determine the sequelae of prolonged REBOA in a nonhuman primate animal model.

SUMMARY BACKGROUND DATA

Prolonged duration of REBOA is associated with adverse clinical outcomes. Threshold occlusion values tied to relative risk have yet to be determined.

METHODS

Juvenile baboons were subjected to 40% to 55% total blood volume hemorrhage to achieve profound hypotension and shock. Zone I REBOA was performed for 60 minutes to assess acute injury and survival at 4 hours (group 1; n = 7). Post-REBOA 10-day survival and complications were then compared between 60 minutes (group 2; n = 8) and 30 minutes (group 3; n = 6) REBOA animals.

RESULTS

Overall survival was 20/21 (95%). IL-6 and IL-8 were elevated at 1 and 4 hours in group 1 (P = 0.005; P = 0.001). Comparing 60-minute REBOA with 30-minute REBOA, there was (1) hypertension compared with normotension (P = 0.005), (2) increased base deficit (P = 0.003), (3) elevated Troponin I (P = 0.04), and histological evidence of kidney injury (P = 0.004). In addition, group 2 demonstrated paralysis with histopathologic changes of spinal cord ischemia (SCI) in 4/8 (50%), with no SCI in group 3 (P = 0.033).

CONCLUSIONS

REBOA limits mortality in the primate model of severe hemorrhagic shock. However, unopposed balloon inflation in the distal thoracic aorta for 60 minutes results in high rates of spinal cord ischemia, an effect mitigated by limiting balloon inflation to 30 minutes.

Thoracic Trauma: Aortic Injuries

Thoracic aortic injuries caused by high impact trauma are life-threatening and require emergent diagnosis and management. With improvement in the acute care services, an increasing number of such injuries are being managed such that patients survive to undergo definitive therapies. A high index of clinical suspicion is required to order appropriate imaging. Computed tomography angiography is used to classify the injuries and guide treatment strategy. While low-grade injuries might be managed conservatively, high-grade injuries require urgent surgical or endovascular intervention. Over the past decade, endovascular repair of the thoracic aorta with or without a surgical bypass has become the preferred treatment with reduced mortality and morbidity. Rapid advancements in the stent graft technology have reduced the anatomic barriers to endovascular therapy and increased the confidence of the operators. Detailed planning prior to the procedure, understanding of the anatomy, correct choice of hardware, and adherence to technical protocol are essential for a successful endovascular procedure. These patients are often young and the limited data on the long-term outcome of aortic stent grafts make a case for a robust follow-up protocol.

TEVAR versus open repair of blunt traumatic descending aortic injury in polytraumatic patients involved in motor vehicle accidents

Background

Thoracic endovascular aortic repair (TEVAR) is the standard-of-care for treating traumatic aortic injury (TAI). Few retrospective studies compared TEVAR to open repair in blunt traumatic aortic injury (BTAI). Our objectives were to compare the early outcomes of TEVAR for blunt traumatic descending aortic injury to open repair (OR) in polytraumatic patients involved in motor vehicle accidents (MVA).

Results

Between February 2005 and April 2017, 71 patients with TAI due to MVA presented to our institution. All patients with descending aortic injuries were considered for open repair (n = 41) or TEVAR (n = 30) if there was no contraindication. The primary outcome was mortality, and secondary outcomes were stroke, paraplegia, intensive care unit (ICU), and hospital stay.

The mean age was 28.4 ± 10.1 years in the OR group and 33.3 ± 16.6 years in TEVAR-group (P = 0.13). The injury severity scores were 41 ± 10 in the OR group and 33 ± 17 in the TEVAR group (P = 0.03). Patients in the OR group underwent emergency repair with a mean time of 0.56 ± 0.18 days from arrival. The TEVAR group had a longer time interval between arrival and procedure (2.1 ± 1.7 days, P = 0.001). The OR group had more blood transfusion (24 (58.5%) vs. 8 (27.5%), P = 0.002), renal impairment (6 (14.6%) vs. 1 (5.50%), P = 0.23), and wound infection (21 (51.2%) vs. 3 (10%), P < 0.001). Three TEVAR patients had a perioperative stroke compared to two patients in the OR group (P = 0.64). There was no difference in the mean ICU (6 ± 8.9 vs. 5.3 ± 2.9 days; P = 0.1) or hospital stay (20.1 ± 12.3 vs. 20.1 ± 18.3, P = 0.62) between the two groups. There were four deaths in the OR group and none in the TEVAR group (P = 0.13).

Conclusion

The results of TEVAR were comparable with the open repair for traumatic aortic injury with good early postoperative outcomes. TEVAR repair could be associated with lower mortality, blood transfusion, and infective complications. However, the complexity of the injury and technical challenges were higher in the open group.

Intraoperative balloon occlusion of the aorta for blood management in sacral and pelvic tumor resection: A systematic review and meta-analysis

BACKGROUND

Neoplasms of the sacrum and pelvis are challenging to manage due to their complex vascularity and size and are at high risk of bleeding during resection. Intra-aortic balloon occlusion (IABO) has been used in trauma to control massive blood loss, but its efficacy and safety in oncologic sacral and pelvic surgery are unknown. The primary objective of this systematic review and meta-analysis was to assess the effectiveness of IABO in providing hemorrhage control during resection of sacral and pelvic tumors.

METHODS

This PROSPERO pre-registered study meta-analyzed all studies reporting on the use of IABO in the setting of pelvic and sacral tumour resection, in accordance with the PRISMA guidelines. The primary outcome of the meta-analysis was intraoperative blood loss, with secondary outcomes consisting of transfusion volume, post-operative blood loss, operative time, complication rate, and mortality.

RESULTS

Across studies, IABO was associated with a large, significant reduction in intraoperative blood loss (SMD -0.81, 95% CI -1.01 to -0.60, P < 0.0001) and transfused red blood cell volume (SMD 0.92, 95% CI -1.30 to -0.53, P < 0.0001). Two studies reported that complication rates were comparable between patients receiving IABO and patient receiving conventional surgery (Odds ratio = 1.29, 95% CI: 0.59 to 2.83, P = 0.52). All studies descriptively reported improved visualization of the operative field with IABO.

CONCLUSIONS

Our findings demonstrated that IABO is an effective technique to decrease blood loss and transfusion requirements during sacral and pelvic tumor surgery. Future clinical trials should be conducted to establish the safety of this method and explore potential contraindications.

The Safety Profile of Intentional or Iatrogenic Sacrifice of the Artery of Adamkiewciz and Its Vicinity's Spinal Segmental Arteries: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

There is paucity of consensus on whether (1) the artery of Adamkiewicz (AoA) and (2) the number of contiguous segmental spinal arteries (SSAs) that can be safely ligated without causing spinal cord ischemia. The objective of this review is to determine the risk of motor neurological deficits from iatrogenic sacrifice of the (1) AoA and (2) its vicinity's SSAs.

METHODS

Systematic review of the spine and vascular surgery was carried out in accordance to PRISMA guidelines. Outcomes in terms of risk of postoperative motor neurological deficit with occlusion of the AoA, bilateral contiguous SSAs, or unilateral contiguous SSAs were analyzed.

RESULTS

Ten articles, all retrospective case series, were included. Three studies (total N = 50) demonstrated a postoperative neurological deficit risk of 4.0% when the AoA is occluded. When 1 to 6 pairs of SSAs (without knowledge of AoA location) were ligated, the postoperative neurological deficit risk was 0.6%, as compared with 5.4% when more than 6 bilateral pairs of SSAs were ligated (relative risk [RR] = 0.105, 95% CI 0.013-0.841, P = .0337). For unilateral ligation of SSAs of two to nine levels, the risk of postoperative neurological deficit does not exceed 1.3%.

CONCLUSION

The current best evidence indicates that (1) occlusion of the AoA and (2) occlusion of up to 6 pairs of SSAs is associated with a low risk of postoperative neurological deficit. This limited number of low quality studies restrict the ability to draw definitive conclusions. Ligation of AoA and SSAs should only be undertaken when absolutely required to mitigate the small but devastating risk of paralysis.

Clinical use of resuscitative endovascular balloon occlusion of the aorta (REBOA) in civilian trauma systems in the USA, 2019: a joint statement from the American College of Surgeons Committee on Trauma, the American College of Emergency Physicians, the National Association of Emergency Medical Services Physicians and the National Association of Emergency Medical Technicians

This is a joint statement from the American College of Surgeons Committee on Trauma, the American College of Emergency Physicians, the National Association of Emergency Medical Services Physicians and the National Association of Emergency Medical Technicians regarding the clinical use of resuscitative endovascular balloon occlusion of the aorta (REBOA) in civilian trauma systems in the USA. This statement addresses the system of care needed to manage trauma patients requiring the use of REBOA, in light of the current evidence available in this patient population. This statement was developed by an expert panel following a comprehensive review of the literature with representation from all sponsoring organizations and the US Military. This is an update to the previous statement published in 2018. It has been formally endorsed by the four sponsoring organizations.

Bypass Techniques for Descending Thoracic Aortic Surgery

The conduct of partial left heart bypass or partial car diopulmonary bypass (CPB) during surgery involving the descending thoracic aorta or thoracoabdominal aorta is one of the most unappreciated and misunder stood extracorporeal circulation procedures in cardio vascular surgery. It is different from conventional CPB, and although some uninitiated practitioners consider it simpler, it is in fact more complicated than conven tional CPB and involves different concepts. It requires expertise and skill in regulating the flow, pressure, and oxygenation of blood going to both the proximal and distal parts of the body and management of the special bypass or shunt procedures used, specialized monitor ing, and knowledge about the protection and preserva tion of organs both proximal and distal to the aortic clamping. It demands exquisite communication and un derstanding of the unique problems faced by the sur geon, anesthesiologist, and perfusionist.

Cardiopulmonary bypass through a left thoracotomy using venous drainage from the innominate vein in congenital heart surgery

Cardiopulmonary bypass (CPB) through a left lateral thoracotomy is a useful approach for some congenital heart procedures, although vascular access for the arterial and venous cannulation can be challenging in the selective patients. Six patients underwent successful extracorporeal circulation through a left lateral thoracotomy using the innominate vein for venous drainage. No operative deaths or major complications occurred. Venous drainage solely from the innominate vein was adequate to establish partial bypass without the need for pericardiotomy. Total bypass was established with combined venous drainage from the innominate vein and the main pulmonary artery. Exposure of the systemic atrioventricular valve was excellent through a left thoracotomy. Venous drainage from the innominate vein without using atrial drainage can safely be used for extracorporeal circulation through a left lateral thoracotomy without compromising the procedure and it is a useful approach to congenital heart surgery in selected patients.

Heat shock proteins as biomarkers for the rapid detection of brain and spinal cord ischemia: a review and comparison to other methods of detection in thoracic aneurysm repair

The heat shock proteins (HSPs) are members of highly conserved families of molecular chaperones that have multiple roles in vivo. We discuss the HSPs in general, and Hsp70 and Hsp27 in particular, and their rapid induction by severe stress in the context of tissue and organ expression in physiology and disease. We describe the current state of knowledge of the relationship and interactions between extra- and intracellular HSPs and describe mechanisms and significance of extracellular expression of HSPs. We focus on the role of the heat shock proteins as biomarkers of central nervous system (CNS) ischemia and other severe stressors and discuss recent and novel technologies for rapid measurement of proteins in vivo and ex vivo. The HSPs are compared to other proposed small molecule biomarkers for detection of CNS injury and to other methods of detecting brain and spinal cord ischemia in real time. While other biomarkers may be of use in prognosis and in design of appropriate therapies, none appears to be as rapid as the HSPs; therefore, no other measurement appears to be of use in the immediate detection of ongoing severe ischemia with the intention to immediately intervene to reduce the severity or risk of permanent damage.

Giant aneurysm after aortic coarctation: repair without circulatory arrest

We describe the case of a 23-year-old patient presenting for redo aortic arch surgery because of recoarctation and poststenotic aneurysm formation after patch aortoplasty in infancy. Using the hemi-clamshell approach, the entire aortic arch was replaced and the supraaortic branches were reimplanted. The applied surgical technique using hypothermic extracorporeal circulation without cardiac arrest allowed an uninterrupted cerebral and spinal cord perfusion due to stepwise clamping of the aortic arch during reconstruction and resulted in an excellent neurologic outcome at six-month follow-up. 

Selective use of left heart bypass for aortic coarctation

BACKGROUND

We evaluated left heart bypass (LHB) for spinal cord protection during aortic coarctation repair in patients with mild (primary, postsurgical, or intervention) and complex coarctation.

METHODS

Between 1990 and 2008, 19 patients (mean age, 21 years; weight, 70 +/- 16 kg) using LHB were compared with 27 patients (mean age, 16 years; weight, 65 +/- 8 kg) undergoing coarctation repair without LHB (non-LHB). Follow-up was similar (LHB, 5 +/- 4 vs non-LHB 4 +/- 3 years; p = 0.81).

RESULTS

Cohorts were similar in age and body surface area. No non-LHB patient lost somatosensory evoked potential or had a femoral artery pressure below 45 mm Hg with test clamping. LHB more often allowed graft interposition (18 of 19 [95%] vs non-LHB, 7 of 27 [26%]; p < 0.003) and a longer clamp time (LHB 44 +/- 16 vs non-LHB 31 +/- 12 minutes p < 0.003) without spinal cord ischemia. Two non-LHB patients had temporary spinal cord paresis. No early or late deaths occurred. Reintervention (LHB, 2 of 19 [11%] vs non-LHB, 2 of 27 [7%]; p = 0.82) and antihypertensive requirements were similar (LHB, 9 of 19 [40%] vs non-LHB, 8 of 27 [30%]; p = 0.35). The late peak transcoarctation gradient was 8 +/- 6 mm Hg in the LBH cohort vs 18 +/- 11 mm Hg in non-LBH patients (p= 0.001).

CONCLUSIONS

Although the adequacy of spinal cord collateral assessment in coarctation repair is imperfect, no spinal cord ischemia occurred with coarctation repair and LHB. We recommend LHB in patients with mild or complex coarctation.

Overview of Great Vessel Trauma

Traumatic injury to the aorta and the brachiocephalic branches are potentially lethal injuries. Specialized preoperative imaging and medical management can lead to better outcomes in this group of patients. In addition, improved surgical techniques for spinal cord protection have led to decreased morbidity in surgical candidates. TEVAR remains a promising technique; however, long-term data currently are not available.

Use of partial cardiopulmonary bypass for coarctation repair through a left thoracotomy in children without collaterals

BACKGROUND

Paraplegia is a devastating complication of coarctation of the aorta (COA) repair. Since 1990 we have used left atrium-to-descending aorta cardiopulmonary bypass (CPB) for COA repair in patients with inadequate collaterals. We reviewed the results with that strategy and compared this CPB group with COA repairs in which CPB was not used to see whether there was any increase in morbidity or delay in recovery.

METHODS

From 1990 to 2006, 11 patients with COA were identified to have inadequate collaterals based on preoperative examination and intraoperative arterial monitoring and test clamp. Left thoracotomy with left atrium-to-descending aorta CPB was used in all. Age ranged from 4.2 to 17.4 years (mean, 8.7 +/- 4.6 years). Two were reoperations for recurrent COA, 3 patients had four prior transcatheter balloon dilatations. One patient had aberrant origin of the right subclavian artery. Operative techniques included resection with extended end-to-end anastomosis (n = 6), interposition graft (n = 4), and patch repair (n = 1). During the same period 71 patients older than 1 year of age had COA repair without CPB. Age ranged from 1.1 to 46.1 years (mean, 7.6 +/- 7.1 years; p = 0.6).

RESULTS

Preoperative imaging of CPB patients demonstrated absence of collaterals (n = 7), possible collaterals (n = 2), small collaterals (n = 1), and anomalous origin of the right subclavian artery (n = 1). Preoperative arm leg gradient in CPB patients was 36.0 +/- 9.0 mm Hg versus 49.9 +/- 15 mm Hg in non-CPB patients (p < 0.01). Mean distal femoral artery pressure with aortic test clamp was 34.3 +/- 4.8 mm Hg in CPB patients versus 49.8 +/- 12.4 mm Hg in non-CPB patients (p < 0.01). Mean CPB flow was 53% +/- 7.3% of calculated total flow. Cardiopulmonary bypass time ranged from 17 to 46 minutes (mean, 27.5 +/- 9.7 minutes). Aortic clamp time in CPB patients ranged from 15 to 33 minutes (mean, 21.6 +/- 6.3 minutes). In the non-CPB group aortic clamp time ranged from 10 to 50 minutes (mean, 23.4 +/- 7.5 minutes; p = 0.5). In the CPB group length of stay ranged from 3 to 7 days (mean, 4.9 +/- 1.3 days), and in the non-CPB group length of stay ranged from 3 to 12 days (mean, 4.7 +/- 1.4 days; p = 0.5). No patient had a neurologic complication. There were no other major complications in the CPB group (eg, bleeding, recurrent laryngeal nerve injury, re-COA).

CONCLUSIONS

Preoperative imaging and a lower arm-to-leg gradient in this series of COA patients suggested inadequate collateral circulation with the potential need for CPB. A femoral artery pressure of less than 45 mm Hg during test clamp was used as an indication for partial CPB. The use of left atrium-to-descending aorta CPB with just over 50% calculated total flow protected the spinal cord in a safe and expeditious fashion. Use of left heart bypass did not affect morbidity or recovery time as compared with COA repair in non-CPB patients.

Velocity-encoded magnetic resonance image assessment of regional aortic flow in coarctation patients

BACKGROUND

During primary coarctation repair, collateral blood vessels contribute significantly to distal perfusion. We sought to determine if velocity-encoded cine magnetic resonance imaging (VENC-MRI) could provide insight into anatomy and hemodynamics of collateral flow in patients with unrepaired coarctation.

METHODS

Sixteen patients (median age, 6.2 years; range, 1 to 18) with discrete coarctation (65% severe, 29% mild-moderate) and 10 controls (median age, 12.0 years; range, 9 to 15) without left-sided heart lesions were referred for cardiac MRI. Flow volumes were calculated from VENC-MRI images at the coarctation (proximal), diaphragm (distal), and midway between the two points (midpoint). A means model, repeated-measure analysis, was performed for volumes.

RESULTS

In coarctation patients, flow volumes increased by 59% (p = 0.0002) from coarctation to diaphragm, primarily between the proximal and midpoint sites (by 77%, p < 0.0001). In controls, flow volumes decreased by 11% along the entire aortic study length. Coarctation volumes were lower than controls by 54% (p = 0.0003) at the proximal site but showed no statistical difference at the midpoint or diaphragm.

CONCLUSIONS

Coarctation flow volumes maximally increase in the upper thoracic aorta, but approach normal flow volumes in the lower thoracic region. Arteries arising from mid and lower thoracic level, such as those supplying the anterior spinal cord, may have nearly normal flow if collaterals are present. Velocity-encoded MRI can evaluate flow in patients who have poor collateral circulation to improve surgical planning and decrease neurologic complications of coarctation repair.

Blunt and Penetrating Trauma to the Thoracic Aorta

Blunt and penetrating trauma to the thoracic aorta carries a highmortality at the scene of injury. The patients who arrive salvageable to the hospital need rapid diagnosis and treatment of the thoracicvessel injury. Blunt aortic injury is usually due to motor vehicle accidents. Penetrating injuries due to stab wounds or gunshot injury are regionally specific. The cardiac and pulmonary systems are associated with injury to the tho racic aorta in the majority of cases. The use of radiologic stud ies and recently, transesophageal echocardiography, aid in defining the site of injury and if there is accompanying cardiac injury. Large bore intravenous ines, multiple arterial lines, a pulmonary artery catheter to manage fluid replacement, and a double lumen endobronchial tube are needed for anesthetic management. The majority of patients die from exsanguina tion. There isneed while repairing the thoracic aorta, to main tain perfusion to the spinal cord with various methods in order to avoid perioperativeparaplegia. The injuries, diagnostic tests for locating sites of trauma, and perioperative management ap proaches associated with surgical repair are reviewed.

Traumatic rupture of the thoracic aorta: third decade of experience

BACKGROUND

Traumatic rupture of the thoracic aorta is a relatively common injury of deceleration accidents, usually high-speed motor vehicle accidents. Spinal cord injury has been a well-documented complication of surgical management. The use of nonheparinized partial bypass with a centrifugal pump was evaluated for protection against spinal cord injury and reduction of risk of associated injuries.

METHODS

From 1989 to 1999, the third decade of the authors' experience, traumatic rupture was diagnosed in 58 patients (male 46 and female 12; mean age 39.9 years, range 17 to 85). Associated injuries were documented in 98.3% (57 patients). In all, 45 patients (77.6%) had the opportunity for definitive surgical management; 42 (93.3%) were managed with partial cardiopulmonary bypass, 35 without the use of heparin. Full cardiopulmonary bypass was utilized in 1 patient while 2 had repair without cardiopulmonary bypass support. Thirteen patients did not have the opportunity for definitive surgical management, 1 death on arrival, 8 (61.5%) suspected, and 4 (30.8%) diagnosed.

RESULTS

There were 6 deaths in the surgical group, 5 in nonheparinized patients. The causes were intraoperative hypovolemia (2), anoxic brain death after intraoperative cardiac arrest (1), sepsis (1), and adult respiratory distress syndrome (1). The other was in the simple aortic cross-clamp group from intraoperative pulmonary compromise. There was one spinal cord injury, paraparesis in 1 of the 2 patients managed without bypass support. The total hospital stay ranged from 8 to 112 days, primarily owing to management of associated injuries. Of the 13 patients who did not have the opportunity for definitive surgical management, 5 had unsuccessful emergency thoracotomy and 3 survived the hospital course without surgery. Of the total population, the overall mortality was 27.6%, whereas the mortality of the potentially operable patients was 25.8%. Of the surgical group, the intraoperative mortality was 6.7% and 30-day mortality was 13.3%.

CONCLUSIONS

Spinal cord injury was prevented by the use of partial cardiopulmonary bypass. Nonheparinized bypass was likely to be a contributory factor to lack of mortality directly related to associated injuries.

Clinical decision making and operative approaches to thoracic aortic aneurysms

The care of the patient with thoracic aneurysms is quite complicated. The decision to treat an aneurysm must be based on the risk of rupture and the patient's life expectancy. The preoperative evaluation must include detailed imaging to allow proper preoperative planning. This is especially important to determine the need for hypothermic circulatory arrest or the potential to treat a descending aneurysm with an endovascular approach. Thorough preoperative preparation and intraoperative care are as important as surgical decision making and meticulous technique. Although significant advances have been made in operative approaches, cerebral and myocardial preservation, and postoperative care, the management of complicated aneurysms of the thoracic aorta is frequently a humbling experience.

Prevention of spinal cord ischaemic complications after thoracoabdominal aortic surgery

Since the publication of prior reviews on this topic, substantial clinical experience with a variety of operative strategies to prevent ischaemic cord complications has been reported. The available data on angiographic localisation of critical intercostal vessels, and, in particular, the evoked potential response to cross-clamping in patients indicates that risk of paraplegia varies considerably even among patients with equivalent TAA extent. Factors such as individual development of the ASA, patent critical intercostals, and the particulars of collateral circulation when intercostal aortic ostia are already occluded likely account for this variability. Information available from SSEP monitoring relative to the dynamic course of cord ischaemia with cross-clamping, and the parallel, if not, frustrating experience with angiographic localisation and intercostal vessel reconstruction indicates that a narrow temporal threshold of cord ischaemia with clamping is present in many patients. This reinforces the importance of both expeditious clamp intervals, critical intercostal re-anastomoses, and the desirability of neuroprotective manoeuvres during cross-clamp induced cord ischemia. As suggested in compelling experimental work our contemporary clinical experience, and predicted by prior reviewers, regional cord hypothermia provides significant promise for limiting or eliminating, in particular, immediate perioperative deficits. Avoidance of postoperative hypotension, spinal cord oedema, and preservation of critical intercostal vessels are additional strategies necessary to impact the development of delayed deficits favourably.

Surgical controversies: coarctation

Fifty one years have passed since grossand Crafoord independently reported successful repair of aortic coarctation. One could be forgiven for assuming that all the surgical controversies have now been settled. This is far from the case, as the numerous publications (frequently with opposing view points) related to timing, technique and complications bear testament. Perhaps the passage of the golden anniversary of this operation should stimulate a degree of reflection among surgeons and cardiologists.

Thoracoabdominal aneurysm repair: perspectives over a decade with the clamp-and-sew technique

OBJECTIVES

Experience over a decade with thoracoabdominal aortic aneurysm (TAA) repair using a clamp-sew technique was reviewed to compare overall results with alternative operative methods.

SUMMARY BACKGROUND DATA

Controversy continues as to the optimal technique for TAA repair, with frequent contemporary emphasis on bypass-distal perfusion methods. Proponents of this technique claim improved results compared to those of historic control subjects in the parameters of operative mortality, postoperative renal failure, and lower extremity neurologic deficit.

METHODS

Over the interval from 1987 to 1996, 160 TAA repairs (type I, 32%; type II, 15%; type III, 34%; and type IV, 19%) were performed in 157 patients with a mean age of 70 years and a male-to-female ratio of 1/1. Clinical features included ruptured TAA (10%), urgent operation (22.5%), and aortic dissection (18%). Operative management used a clamp-sew technique with regional hypothermia for spinal cord (epidural cooling, since 1993) and renal protection. Variables associated with the endpoints of operative mortality or major morbidity, particularly spinal cord injury, were assessed with Fisher exact test and logistic regression; late survival was estimated with the Kaplan-Meier method.

RESULTS

In-hospital mortality was 9% and was associated with operation for rupture (p < 0.005) or other acute presentation (p < 0.001). After multivariate analysis, the postoperative complication renal failure (relative risk, 6.5 [95% confidence interval, 1.8-23.6, p = 0.004]) and significant spinal cord injury (relative risk, 16.5 [95% confidence interval, 3.2-83.2, p = 0.001]) were associated independently with operative mortality. Paraparesis-paraplegia occurred in 7%, an incidence significantly (p < 0.001) less than that (18.7%) predicted for this cohort from published models. Variables associated (univariate analysis) with this complication included TAA rupture (p < 0.0001), other acute presentation or dissection (p < 0.001), prolonged (>6 hours) operation (p < 0.04), and excessive (>3 L) transfusions (p < 0.02). Operation for acute presentation or dissection (relative risk, 7.9 [95% confidence interval, 1.7-37.7, p = 0.009]) and prolonged surgery [relative risk, 7.5 [95% confidence interval, 1.5-35.3, p = 0.01]) retained independent association with paraplegia-paraparesis after multivariate analysis. Dialysis was needed in 2.5%. Late survival at 1 and 5 years was 86 +/- 2.9% and 62 +/- 5.8%, respectively.

CONCLUSIONS

These data compare favorably with those from contemporary reports using other operative strategies and do not support routine adoption of bypass-distal perfusion as the preferred technique for TAA repair.

Techniques for retrograde cerebral perfusion in the treatment of aortic lesions via left thoracotomy

Retrograde cerebral perfusion under deep hypothermic circulatory arrest is a simple and useful adjunct in aortic surgery and is performed by many surgeons in the treatment of aortic arch pathology. In recent years, this technique has been recommended in the surgery of distal arch and proximal descending aortic lesions through a left thoracotomy inclusion. The aim of the technique is to increase the right atrial pressure for retrograde cerebral perfusion. After cooling using femorofemoral bypass, circulatory arrest is initiated. The right atrial pressure is increased to 20 mmHg, and retrograde cerebral circulation results. In this article, five patients with distal aortic arch and proximal descending thoracic aortic lesions who were operated on by using this technique were evaluated. It is suggested that this technique can be used with a lateral thoracotomy approach that is suitable for procedures on a distal aortic arch and proximal descending aorta.

Effect of spinal cord preconditioning on paraplegia during cross-clamping of the thoracic aorta

BACKGROUND

Paraplegia is a devastating complication of operations for thoracic or thoracoabdominal aneurysms. Preconditioning the brain with sublethal ischemia induces resistance to subsequent ordinarily lethal ischemia (ischemic tolerance). We investigated whether ischemic tolerance could be induced by preconditioning canine spinal cord. The role of heat-shock proteins (HSP) in this process was investigated.

METHODS

In experiment 1, the preconditioning group (n = 6) had aortic cross-clamping for 20 minutes, whereas controls (n = 6) had no cross-clamping. After 48 hours the aorta was cross-clamped for 60 minutes in both groups. Neurologic examination was performed 24 hours later and the spinal cord was studied for immunohistochemically. In experiment 2, either 48 hours after 20 minutes of clamping or after sham operation (n = 4), HSP were investigated immunohistochemically.

RESULTS

In experiment 1, 3 of 6 controls became paraplegic but none of the 6 preconditioning group dogs became paraplegic. The HSP appeared on sections from all 6 PC dogs and 3 control dogs that did not exhibit paraplegia. In experiment 2, HSP were present in clamped animals but could not be detected after sham operation.

CONCLUSIONS

Ischemic tolerance was induced by preconditioning the canine spinal cord, in which HSP are believed to be involved.

Is clamp and sew still viable for thoracic aortic resection?

OBJECTIVE

The authors reviewed the morbidity and mortality of surgical resection of the descending thoracic and thoracoabdominal aorta using the clamp-and-sew technique.

BACKGROUND

Paraplegia remains a devastating complication after thoracoabdominal aortic resection, despite many strategies for spinal cord protection. Because of its simplicity, clamp and sew has been the preferred technique at the University of Virginia for the thoracoabdominal aortic resection when proximal control is possible.

METHODS

Between 1987 and 1994, the authors reviewed 91 consecutive patients who underwent thoracic aortic resection using clamp-and-sew techniques without any additional adjuncts for spinal cord protection.

RESULTS

The average age of patients was 60.8 years; 57.1% were male. No intraoperative deaths occurred. In-hospital mortality was 13% (12/91), with an overall incidence of postoperative spinal cord injury manifested as paraparesis or paraplegia of 9.9% (9/91). Eighty-nine percent (81/91) of all repairs were completed with aortic clamp times of 40 minutes or less, and nearly six out of ten were completed in 30 minutes or less (53/91). Cross-clamp times were not significantly different between those patients who sustained neurologic injury and those who had no deficits.

CONCLUSIONS

The authors conclude that clamp and sew is still a viable technique for thoracoabdominal aortic resection. Nearly all resections can be completed within 40 minutes of aortic occlusion. However, the "safe" duration of thoracic aortic occlusion remains unknown, and spinal cord injury can occur even with short clamp times. Reproducible, safe, and technically simple means of spinal cord protection must be developed.