Mechanical circulatory support during repair of thoracic aortic injuries improves morbidity and prevents spinal cord injury

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.

Endovascular approach to acute aortic trauma

Traumatic thoracic aortic injury remains a major cause of death following motor vehicle accidents. Endovascular approaches have begun to supersede open repair, offering the hope of reduced morbidity and mortality. The available endovascular technology is associated with specific anatomic considerations and complications. This paper will review the current status of endovascular management of traumatic thoracic aortic injuries.

Current management of traumatic rupture of the descending thoracic aorta

Traumatic rupture of the descending thoracic aorta remains a leading cause of death following major blunt trauma. Management has evolved from uniformly performing emergent open repair with clamp and sew technique to include open repair with mechanical circulatory support, medical management and most recently, endovascular repair. This latter approach appears, in the short term, to be associated with perhaps better outcome, but long term data is still accruing. While an attractive option, there are specific anatomic and physiologic factors to be considered in each individual case.

The Endovascular Approach to Acute Aortic Trauma

Endovascular repair of the traumatically injured thoracic aorta has emerged as an exceptionally promising modality that is typically quicker than open repair, with a reduced risk of paralysis. There are a specific set of anatomic criteria that need to be applied, which can be rapidly assessed by the CT angiogram. The enthusiasm for endovascular repair must be tempered by recognition of the complications and lack of long-term follow-up, particularly in younger patients. Surgeons who are skilled in open aortic repair must not only be involved, but should take on a leadership role during the planning, deployment, and follow-up of these patients. Familiarity with all of the available devices expands treatment options. As more specific devices become available, and more follow-up is accrued, the role of endovascular stents will continue to grow.

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.

The effect of changing presentation and management on the outcome of blunt rupture of the thoracic aorta

BACKGROUND

The management of traumatic aortic rupture has evolved from emergency surgery for all to incorporating nonoperative and endovascular approaches. In addition, the greater emphasis on restraint systems over the past decade might result in lower immediate mortality.

METHODS

We reviewed our contemporary experience with reference to a previous report from the same institution to determine whether there has been improvement in outcome related to these factors.

RESULTS

In 1990, a review of 104 patients admitted to our center over a 15-year period (1975-1990) noted an overall mortality of 65%. Forty-two patients died before they could reach the operating room, including 15 who were declared dead on arrival and 27 who died before reaching the operating room. All patients underwent angiography, followed by immediate operation. The mortality rate of those who reached the operating room was 34%, and paralysis-paraplegia occurred in 26% of survivors. A review of 53 patients admitted between January 1, 2000, and April 2005 documented an overall mortality of 26% and a paralysis rate of 4.5% in operative survivors. Only 3 patients died during initial evaluation, 2 who were in arrest on arrival. Eight patients were managed nonoperatively, and 13 were managed by means of deliberate delay before intervention to improve physiologic status. Finally, 19 patients were managed with endografts.

CONCLUSION

The improved outcome over the decade since the initial experience reflects both a reduced severity of injury attributable to restraint systems and a more flexible approach to the acute management, which can modify the effect of associated injuries.

Management Options in Blunt Aortic Injury: A Case Series and Literature Review

Blunt aortic injury (BAI) is a devastating consequence of high-energy trauma. The majority of its victims do not survive; those who do generally have significant associated injury. The standard treatment of BAI has been emergent replacement or repair of the damaged aorta via a posterolateral thoracotomy, with or without perfusion adjuncts. In addition to the substantial morbidity and mortality secondary to multisystem traumatic injuries, patients surviving to reach the operating room have been exposed to the risks related to their surgical treatment, namely death, paraplegia, hemorrhage, transfusion, organ dysfunction, prolonged intensive care unit stays, and extensive rehabilitation requirements. Contributions to the literature over the past several years have provided support for changing practice patterns in the management of BAI. Aggressive control of blood pressure has made it safe to delay high-risk interventions in patients with complex injuries. Advanced perfusion strategies using little or no anticoagulation appear to have positively affected bleeding complications and neurologic risk. Finally, endovascular stent grafting, though not yet rigorously evaluated in BAI, has been shown to be feasible and effective in the short term. This case presentation and literature review will examine treatment options and propose a management algorithm.

Complex blunt aortic injury or repair: beneficial effects of cardiopulmonary bypass use

OBJECTIVE

To compare the outcomes and associated morbidity in patients with blunt aortic injury (BAI) repaired using cardiopulmonary bypass versus no bypass. Special consideration is given to the influence of bypass in the outcome of complex injuries or repair circumstances.

SUMMARY BACKGROUND DATA

There are conflicting data concerning the utility of bypass techniques in the operative management of BAI, and controversy over the subject persists. During the last decade, surgeons at the authors' institution have undergone a change in philosophy concerning management of these injuries and began almost exclusively using cardiopulmonary bypass for the repair in 1996. This project explores the effects of this change in the management of BAI.

METHODS

The records of all patients with BAI admitted to a level 1 trauma center over a period of 12 years were reviewed for demographics, injury characteristics, operative technique, and outcome. The bypass group was compared to the no bypass group with respect to morbidity and mortality. Those with a complex injury or repair (CI/R) were examined as a subgroup. CI/R was defined as the presence of an injury with extension proximal to the subclavian artery, involvement of branch vessels, or requirement of maneuvers interfering with anastomosis construction, such as cardiac massage.

RESULTS

From January 1, 1990, to December 31, 2001, 91 patients were admitted to Wake Forest University Baptist Medical Center with BAI. Sixty-five of these underwent operative repair. Sixty (32 no bypass, 28 bypass) survived to the immediate postoperative period. Injury Severity Score was similar (33 no bypass, 31 bypass, P =.48), as was admission base deficit (-9.2 m Eq/L no bypass vs. -7.0 mEq/L B, P =.13). Paraplegia occurred in four (12%) of the no bypass group as opposed to 0 of the bypass group (P =.05). No patient in the bypass group experienced complications related to heparinization, and two (7%) experienced bypass-related complications (cerebral edema, femoral vein laceration). Mean clamp time for the entire group was 27 minutes. Examination of the 10 patients with CI/R who survived the operating room showed markedly longer clamp times (59 minutes vs. 22 minutes, P <.0001) and a higher rate of paraplegia/paresis (30% vs. 2%, P =.01) as compared to those without CI/R. Logistic regression demonstrated a significant relationship between increasing clamp time and the CI/R classification (P =.007). All three (100%) of the CI/R patients repaired via clamp-and-sew technique developed paraplegia, while none of the seven CI/R patients repaired on bypass developed neurologic changes (P =.008).

CONCLUSIONS

With the use of cardiopulmonary bypass in the repair of BAI, the incidence of paraplegia/paresis has fallen. While patients with typical injuries and uncomplicated repair can expect good results with either technique, cardiopulmonary bypass provides significant advantages in the repair of those with CI/R. With the use of bypass, no CI/R patient developed paraplegia, while all CI/R patients experienced paraplegia before bypass use. Although others have reported the importance of clamp time, in this series clamp time appeared largely to be a surrogate variable for complexity of injury.

Management of traumatic aortic rupture: a 30-year experience

OBJECTIVE

To present the authors' 30-year experience with traumatic aortic rupture (TAR).

SUMMARY BACKGROUND DATA

TAR is a highly lethal injury. Most institutions manage a small number of cases, and most surgeons receive only modest exposure during training.

METHODS

Between 1971 and 2001, the authors operated on 219 patients with a diagnosis of TAR. Diagnosis of TAR since 1994 has been based exclusively on the use of contrast-enhanced spiral computed tomography, with angiography reserved for equivocal cases (periaortic mediastinal hematoma without aortic wall abnormalities). Patients were divided according to surgical technique. Eighty-two patients (group A) were operated on with a clamp-and-sew technique. Sixty-four patients (group B) underwent surgery with the use of a passive shunt, and 73 patients (group C) were treated using heparin-less partial cardiopulmonary bypass.

RESULTS

Mortality was 18 patients for group A (21.9%), 23 patients for group B (35.9%), and 13 patients for group C (17.8%) (P =.03). Paraplegia occurred in 15 of 64 survivors in group A (23.4%), 7 of 41 survivors in group B (17%), and 0 of 60 survivors in group C ( P=.0005). Aortic occlusion without lower body perfusion for longer than 30 minutes (P =.004) and surgical technique without lower body bypass support (P =.0005) were associated with paraplegia.

CONCLUSIONS

Surgery for TAR based on spiral computed tomography screening and diagnosis is reliable. The use of heparin-less distal cardiopulmonary bypass in the authors' hands is safe and is associated with a reduced incidence of paraplegia.

Anatomical considerations in the surgical management of blunt thoracic aortic injury

PURPOSE

Blunt aortic injury (BAI) involving the thoracic aorta is usually described as occurring at the isthmus. We hypothesized that injuries 1 cm or less from the inferior border of the left subclavian artery (LSCA) are associated with an increased mortality rate compared with injuries that are more distal.

METHODS

A retrospective review of patients admitted with the diagnosis of BAI was performed. Injuries were divided into two groups: group I, injuries that were 1 cm or less from the junction of the LSCA and the thoracic aorta; group II, injuries that were more than 1 cm from the LSCA. Primary outcome measures included cross-clamp time, rupture, and death.

RESULTS

In a 14-year period, 122 patients were admitted with BAI. The anatomy relative to the LSCA could be determined in 91 patients who underwent operative repair. Forty-two injuries (46%) were classified as group I, and 49 injuries were classified as group II. Group I injuries were characterized by an increased mortality rate (18/42 or 43% in group I vs 11/49 or 22% in group II, P = .04), intraoperative rupture rate (7/42 or 17% in group I vs 1/49 or 2% in group II, P = .003), and cross-clamp time (39.5 +/- 21.9 minutes in group I vs 28.4 +/- 13 minutes in group II, P = .04). Three ruptures occurred while proximal control was being obtained.

CONCLUSION

Increased technical difficulty and risk of rupture characterize injuries that occur proximally in the descending thoracic aorta, 1 cm from the LSCA. These injuries may be better managed by instituting bypass before attempting to obtain proximal control and by routinely clamping proximal to the LSCA.

Impact of Presenting Physiology and Associated Injuries on Outcome following Traumatic Rupture of the Thoracic Aorta

We hypothesized that the predominant factor influencing outcome of traumatic rupture of the thoracic aorta (TRA) was the degree of shock on presentation and associated injuries. We reviewed our experience with TRA over a 15-year period. Patients were classified as “unstable” if presenting systolic blood pressure was <90 mm Hg or if it decreased to <90 mm Hg after admission. We determined the presence of closed head injury, cardiac risk factors, a preoperative acute lung injury (ALI). The influence of these factors on mortality, postoperative adult respiratory distress syndrome (ARDS), and paralysis was analyzed. One hundred thirty-six patients were admitted with TRA. One hundred twenty underwent operative repair with a mortality of 31 per cent. Operative mortality was significantly higher in unstable patients (62%) versus stable patients (17%, P = 0.001), in patients with cardiac risk factors (71%) versus those without (24%, P = 0.001), and in patients with preoperative free rupture (83%) with versus those without (19%, P = 0.001). Free rupture was the cause of hypotension in only 10 of 42 unstable patients, with the remainder being due to other causes. Preoperative ALI was associated with a marked increase in postoperative ARDS (47% with vs 9% without, P = 0.001) but not operative mortality. Mechanical circulatory support (MCS) was used in 59 cases, none of whom experienced paralysis, whereas eight of 61 operated on without MCS developed paralysis ( P = 0.001). When logistic regression was applied the use of MCS was not determined to be statistically significant. However, preoperative instability was found to be a significant predictor of postoperative paralysis with the risk being increased 5.5 times (confidence interval 3.3–10). The predominant factor influencing mortality, postoperative ARDS, and paralysis was preoperative instability and associated injuries. In patients who are hypotensive, other injuries should take precedence over repair of TRA. Patients who are stable but who have cardiac or pulmonary risk factors may be better managed by a period of nonoperative management until their condition improves.

Choice of venous cannulation for bypass during repair of traumatic rupture of the aorta

BACKGROUND

Choices for venous cannulation for left heart bypass, to assist repair of traumatic rupture of the thoracic aorta, are between the left atrial appendage and pulmonary veins.

METHODS

A retrospective chart review was performed of patients who underwent operative repair of ruptured aorta.

RESULTS

Over a 15-year period between March 1985 and February 2000, 133 patients were admitted to a level I trauma center with aortic rupture. Of the 50 procedures performed with left heart bypass, the left atrial appendage was cannulated in 19 and pulmonary veins in 31 (four superior, 27 inferior). Complications occurred in 7 of the 19 patients who underwent venous cannulation via the atrial appendage (two ventricular fibrillation, three atrial fibrillation, one pericardial effusion leading to tamponade, and one phrenic nerve injury). Complications occurred in 2 patients who underwent cannulation via pulmonary vein (one atrial fibrillation, one pericardial effusion requiring tapping) (p = 0.02).

CONCLUSIONS

Cannulation via the pulmonary veins is associated with a decrease in complication rates compared with cannulation of the atrial appendage.

Heparinless partial cardiopulmonary bypass for the repair of aortic trauma

OBJECTIVE

We hypothesized that partial cardiopulmonary bypass with a heparin-bonded system would be a technically simple, effective adjunct for reducing paraplegia during repair of traumatic aortic rupture. It avoids the risk of heparin, but, unlike left atrial-arterial bypass, it can heat, cool, oxygenate, and rapidly infuse volume if needed.

METHODS

A retrospective review was conducted of patients admitted for aortic trauma from July 1994 to December 1999. Bypass consisted of femoral venous (right atrial) cannulation, a centrifugal pump, and an oxygenator-heater/cooler. Arterial return was to the femoral artery or distal aorta. The entire system was heparin-bonded and no systemic heparin was given.

RESULTS

Heparin-bonded partial bypass was established in 50 patients (mean age 43 +/- 17 years). Crossclamp time was 32 +/- 11 minutes (range 14-70 minutes), mean flow 3.0 +/- 0.8 L/min, and bypass time 64 +/- 43 minutes. During repair, 58% of patients received volume through the system (mean 1.1 +/- 1.9 L). Core temperature rose slightly (35.9 degrees C +/- 0.7 degrees C to 36.3 degrees C +/- 0.8 degrees C). Three of the 15 patients who underwent percutaneous femoral arterial and venous cannulation concomitant with their angiograms had vessel injury, with one limb loss, and this procedure was discontinued. Thirty-five patients underwent percutaneous femoral vein and direct distal aortic cannulation without event. The mortality rate for patients supported by bypass was 10%, and all deaths were due to other injuries. There were no new cases of paraplegia and no worsening of intracranial or pulmonary injuries.

CONCLUSIONS

Heparin-bonded bypass is technically simple to use and avoids the risk of anticoagulation. Paraplegia was avoided. The ability to correct hypothermia, oxygenate, and rapidly infuse volume may simplify management and improve outcomes.

Guidelines for the diagnosis and management of blunt aortic injury: an EAST Practice Management Guidelines Work Group

In summary, BAI is a lethal result of severe blunt trauma. It should be considered in all patients who sustained injury by a deceleration or acceleration mechanism, especially in the face of physical or radiographic findings suggestive of mediastinal injury. Angiography remains the "gold standard" for diagnosis, although CT scanning is taking more of a role, especially for screening. Diagnosis should be followed by prompt surgical repair using some method of distal perfusion to minimize renal and spinal cord ischemia. If prompt repair is not feasible because of other injuries or comorbidities, medical control of blood pressure is warranted in the interim.

Surgical outcome of traumatic rupture of the thoracic aorta

BACKGROUND

The aim of this study was to point out the results of different techniques of spinal cord protection in surgically-treated patients with traumatic thoracic aorta (TTA).

METHODS

A multicentric study was carried out involving 182 patients with TTA. Four patients died before surgery. Two patients were operated on without any investigation and 2 had no aortic tear at thoracotomy. The remaining 174 patients had aortic isthmus disruption and were included in the study. The mean age was 32.3+/-14.29 years with 126 men (72.4%) and 48 women (27.6%). Road accidents were causal in 163 patients (93.66%); polytraumatism was frequent. A standard chest roentgenogram led to a diagnosis which was confirmed with aortography in 94.8% of cases. Surgical repair of visceral lesions was performed in 52 patients (29.9%) for traumatic spleen, liver, diaphragm, mesentery, and gut. These operations were done before or after aortic operation in 21.3% and 8.6% of cases, respectively. Thirty-three patients (19%) died and 9 (5.2%) had paraplegia. Sixty-nine patients had clamp and sew technique (group 1). Ninety-three patients had different types of extracorporeal circulation (group 2), and 12 patients had Gott shunt (group 3). No difference appeared between the 3 groups according to mortality and paraplegia. But the sex ratio, age, visceral lesions, craniocerebral lesions, the type of aortic repair, and cross-clamp time were discriminative.

RESULTS

The univariate analysis point out age, cross-clamp time, hemothorax, and anatomical type of aortic injury as the risk factors of death. This was confirmed by a multivariable test which retained age, cross-clamp time, and hemothorax as risk factors. When not diagnosed in time, TTA is serious and has a bad prognosis. In spite of a high mortality and morbidity, the surgical management has improved. Immediate operation and medullar protection are the stumbling block in this operation.

CONCLUSIONS

Operation can be delayed in some cases, but one must take care of hemodynamic instability. This calls for a repair of the serious associated lesions first, or of a quick performing of a thoracotomy for ruptured aorta. The question remains, is it better to protect the spinal cord with the lower aortic perfusion and avoid the simple cross-clamp? Clinical studies give few answers to this question, and the best answer has not yet been given, as we lack prospective studies in this field.

Recent clinical experience with left heart bypass using a centrifugal pump for repair of traumatic aortic transection

OBJECTIVE

To analyze the indications, results, and limitations of using left atrial to femoral artery (LA-FA) bypass to provide distal perfusion during repair of traumatic aortic injuries.

SUMMARY BACKGROUND DATA

There is no consensus about the best method for repair of traumatic aortic transection. Distal aortic perfusion with LA-FA bypass and a centrifugal pump has been the authors' preferred technique for injuries to the aortic isthmus and descending thoracic aorta.

METHODS

From 1988 to 1998, the authors operated on 30 patients with traumatic aortic transection using LA-FA bypass. The mean age of the group was 36+/-2 years. The mechanism of injury was from a motor vehicle accident in 97% of the cases. Distal aortic perfusion was maintained at 50 to 75 mm Hg with flow rates of 1.5 and 3 L/min. The mean aortic cross-clamp time was 38+/-2 minutes, and the mean bypass time was 49+/-2 minutes.

RESULTS

No complications related to cannulation, arterial thromboembolism, renal failure, mesenteric ischemia, or hepatic insufficiency occurred. There were no cases of postoperative paraplegia and no deaths.

CONCLUSION

Left atrial to femoral artery bypass is a safe, simple, and effective adjunct to the repair of traumatic injuries to the thoracic aorta. Active distal aortic perfusion preserves spinal cord, mesenteric, and renal blood flow and eliminates the potential catastrophic consequence of spinal cord ischemia from an unexpectedly prolonged aortic cross-clamp time.

Traumatic aortic rupture: diagnosis and management

BACKGROUND

Traumatic aortic rupture is a relatively uncommon lesion that presents the cardiothoracic surgeon with unique challenges in diagnosis and management. To address controversial aspects of this disease, we reviewed our experience.

METHODS

The study was performed by retrospective chart review.

RESULTS

Forty-two patients with traumatic thoracic aortic ruptures were managed between January 1988 and June 1997. Nine arrived without vital signs and died in the emergency department. Admission chest radiographs were normal in 3 patients (12%) and caused significant delays in diagnosis. Four of 30 patients admitted with vital signs had rupture before thoracotomy and died. Twenty-six underwent aortic repair. In 1 patient repair was performed with simple aortic cross-clamping, whereas a second was managed with a Gott shunt. The remaining 24 patients had repair with partial left heart bypass. In 1 patient hypothermic circulatory arrest was required. Two patients (7.7%) died. There were no cases of new postoperative paraplegia in the bypass group. There was no morbidity directly attributable to the administration of heparin for cardiopulmonary bypass.

CONCLUSIONS

In a discrete group of patients with traumatic rupture of the aorta, the rupture will become complete during the first few hours of hospital admission; aggressive medical treatment with beta-blockade and vasodilators in the interval before the operation is an essential aspect of management. Active distal circulatory support with partial left-heart bypass provides the optimal means of preventing spinal cord ischemia during repair of acute traumatic aortic rupture.

Outcome of blunt thoracic aortic injury in a level I trauma center: an 8-year review

BACKGROUND

The purpose of this study was to evaluate our experience with blunt thoracic aortic injury and identify factors predictive of outcome.

METHODS

Hospital charts, trauma registry data, and autopsies of 64 patients with blunt thoracic aortic injury from 1988 to 1995 were reviewed.

RESULTS

Patients were identified and segregated based on admission physiology. Group 1 patients (n = 19) arrived in arrest. Group 2 patients (n = 10) arrived in shock with systolic BP 90. Group 3 patients (n = 35) arrived with systolic BP>90. All patients in groups 1 and 2 expired. Injury Severity Scores for nonsurvivors in group 3 (n = 12) were significantly higher than survivors. There were no significant differences when comparing time of injury to repair or arrival between groups, or in mortality or paralysis comparing repair techniques or clamp/bypass times. Double lumen endotracheal tubes caused significant operative delays compared to single lumen tubes.

CONCLUSIONS

Predictors of survivability were hemodynamic stability on arrival and lower Injury Severity Scores. In thoracic aortic injury patients arriving hemodynamically stable, Injury Severity Score correlated with mortality but not paralysis.

Prospective study of blunt aortic injury: Multicenter Trial of the American Association for the Surgery of Trauma

BACKGROUND

Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years.

METHODS

This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma.

RESULTS

There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia.

CONCLUSIONS

Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.