Rupture of the thoracic aorta by broadside impacts in road traffic and other collisions: further angiographic observations and preliminary autopsy findings

Endovascular treatment of an aortic traumatic double rupture

Traumatic thoracic aortic rupture is a life-threatening condition; aortic isthmus is the most common site of rupture, but in rare cases traumatic injury can localize elsewhere, such as at aortic arch or at the level of the diaphragm. In the past few years, endovascular treatment of traumatic aortic injury became a safe procedure, with lower mortality and complication, if compared with open surgery. We report a case of a 40-year-old-man admitted to emergency department after a violent car crash in which an aortic traumatic double rupture was successfully treated with two endovascular stent-grafts coverage.

Delayed rupture of thoracic aorta aneurysm following a kick to the abdomen

Several theories have been proposed to explain the Blunt Traumatic Aortic Rupture (BTAR) because different mechanical forces act on the aorta, at anatomically susceptible sites, including shearing, torsion and stretching, but the origin, transduction and relative importance of these forces remain uncertain. We report a case of a 74-year-old man injured by a kick to the abdomen. After 2 days he felt chest pain paroxysm and weakness in his left leg. The patient was admitted to an emergency care department where he experienced sudden and severe hemodynamic deterioration, dying rapidly. The autopsy, performed 3 days later, showed haemorragic infarction of hypogastric subcutaneous tissues and revealed an extended dissecting aneurysm of the thoracic aorta with following haemopericardium. In our case we considered that a low energy compression to the abdomen, in presence of underlying atherosclerosis, caused aortic dissection rather than rupture and then the 48h time span after the traumatic event and the cardiac tamponade was enough to complete the aortic retrograde dissection. We finally emphasise the importance of the careful surveillance of any trauma close to the abdomen in view of initially unpredictable, as well as eventful injuries. The finding of early signs of neointima formation in thoracoabdominal portions of aortic dissection strongly supported our interpretation. The forensic interest of this case is correlated to the voluntary character of the inflicted injury. The culprit was thus charged with manslaughter.

Evaluation of aortic injury in driver fatalities occurring in motor vehicle accidents in the State of Maryland for 2003 and 2004

Incorporating epidemiological and pathologic factors, a retrospective analysis of aortic injury and driving fatalities was conducted. To better understand the mechanism of injury, data were compiled for decedent demographics, autopsy and toxicology findings, and accident circumstances, with emphasis on directional impact. Review of the autopsy files of the Office of the Chief Medical Examiner in the State of Maryland in 2003 and 2004, identified 150 cases of aortic injury recorded in 537 autopsied drivers. Aortic lacerations occurred in 96% of the cases with aortic injury, two thirds of which were complete or near complete transections. A large percentage of cases involved a side impact collision. Consistent with extant research on frontal and lateral impacts, the majority of aortic injuries occurred at the ligamentum arteriosum. Also, the mechanism of aortic injury seems to be similar for side and frontal impact collisions, involving a combination of rapid deceleration forces along with chest and/or upper abdominal compression. This study emphasizes the importance of side impact collisions as a cause of aortic injury. Aortic lacerations have a high mortality rate and better motor vehicle design may prevent this type of injury.

A novel model of blunt thoracic aortic injury: a mechanism confirmed?

BACKGROUND

There is no consensus on the mechanism of traumatic injury to the thoracic aorta and no reproducible animal model. Advances in injury scene analysis suggest that lateral and oblique force vectors cause aortic injury. We hypothesized that the spectrum of aortic injury could be reproduced in an animal model by application of an obliquely directed load to the pressurized aorta.

METHODS

Graded air impulses of 80, 100, 110, and 120 pounds per square inch (PSI) were delivered to the descending thoracic aorta of 19 swine with a novel pneumatic device. Aortic isthmus strain was recorded with microminiature probes. Gross and microscopic injury was recorded with digital photography.

RESULTS

The spectrum of human aortic injury was reproduced in this model. Deep injuries to the aortic media were common. The majority of injuries occurred within the region of the isthmus. Impulse pressure of 120 PSI caused transections, whereas lower impulse pressure resulted in less severe injuries. Aortic isthmus strain was greater in the animals exposed to 120 PSI than those receiving lower PSI (19.6 +/- 4.9% vs. 8.7 +/- 2.5%, p = 0.067).

CONCLUSIONS

Direct loading of the pressurized descending thoracic aorta causes isthmus injury secondary to aortic wall strain. Deep medial lesions are common and could propagate soon after injury to form pseudoaneurysms. A critical load is required to cause complete uncontained transection with exsanguination, which may have relevance to injury scene death.

Multi-detector computed tomography findings of atypical blunt traumatic aortic injuries: a pictorial review

Traumatic injuries to the aorta are a significant source of morbidity and mortality in trauma patients, which highlights the importance of rapid diagnosis and treatment. Multi-detector row computed tomography has become the primary imaging modality for the imaging assessment of the polytrauma patient because it is fast, noninvasive, and the data sets can be used to create tailored multi-planar reformatted images that optimally display the location and morphology of aortic trauma and its relationship to adjacent structures. Although the classic location of blunt injury to the aorta occurs just distal to the left subclavian artery, aortic injuries may occur at any location along the aorta and in any patient population. Radiologists should be prepared to evaluate these types of injuries in nontraditional planes that are tailored to each examination and to present the data to clinicians using commercially available 3D software for purposes of surgical planning. Here, we review in pictorial form atypical aortic injuries with emphasis on multi-planar reformations.

An Experimental Cadaveric Study for a Better Understanding of Blunt Traumatic Aortic Rupture

BACKGROUND

Blunt traumatic aortic rupture (BTAR) is a common catastrophic injury leading to death. Considerable uncertainty remains regarding the pathogenic cause. This study examines the comportment of the heart and the aorta during a frontal deceleration.

METHODS

Accelerometers were placed in the right ventricle of the heart, the aorta, the sternum, and the spine of six trunks removed from human cadavers. Different vertical decelerations were applied to cadavers and the relative motion of these organs was studied (19 tests).

RESULTS

The deceleration recorded in the isthmus of the aorta was always higher that the one recorded in the heart (p < 0.05). The difference of deceleration was 17% and increased with the speed's fall (extremes 5-25%). There was no significant difference of deceleration between the bony structures of the thorax. These results experimentally demonstrate for the first time that the fundamental mechanism of BTAR is sudden stretching of the isthmus of the aorta.

CONCLUSION

Four mechanisms are suspected to explain the location of the rupture: two hemodynamic mechanism (sudden increase of intravascular pressure and the water-hammer effect), and two physical mechanisms (sudden stretching of the isthmus and the osseous pinch). A greater understanding of the mechanism of this injury could improve vehicle safety leading to a reduction in its incidence and severity. Future work in this area should include the creation of an inclusive, dynamic model of computer-based modeling systems. This study provides for the first time physical demonstration and quantification of the stretching of the isthmus, leading to a computerized model of BTAR.

Computer simulation and validation of the Archimedes Lever hypothesis as a mechanism for aortic isthmus disruption in a case of lateral impact motor vehicle crash: a Crash Injury Research Engineering Network (CIREN) study

OBJECTIVES

Can aortic isthmus disruption occurring in a lateral motor vehicle crash (LMVC) be explained by the Archimedes Lever Hypothesis, where the intrathoracic aorta, super-pressurized by the thoracic impact force, functions as a rigid lever system? The long arm of this lever system is the proximal aorta-aortic arch, the short arm is the aortic isthmus fixed distally at the descending aorta, and the fulcrum is at the great vessels, especially the left subclavian artery.

METHODS

The theory was tested by a simulation technique using a computer-based finite element numerical model system. This simulation model included the dynamics of the crashed vehicles, the direction of force impact, and the structure of the thorax and intrathoracic viscera, including the entire intrathoracic aorta. The specific patient whose data were entered into the model was chosen from a study of 34 LMCV aortic injuries (AIs). The model was constrained by patient and vehicle data from this surviving case.

RESULTS

Three sequential lateral thoracic levels impacted by the vehicle side structures were selected. At each level, the maximum mean intra-aortic pressure was 50 to 100 ms after impact, the structure dynamics of the actual crash and the resultant vehicle deformation were simulated; only when the lateral impact was induced in a transverse plane including the first 4 ribs at the level of the aortic arch/isthmus system, with intra-aortic pressures from 200 to 500 mm Hg, were AI-compatible stresses and deformations in the aortic wall achieved at the isthmus.

CONCLUSIONS

In LMVC AI, the simulation suggests that the aorta functions as an Archimedes Lever System in which the magnified force mediated by the long lever arm produces sufficient strain on the short lever arm to rupture the aorta at the isthmus.

Comparison of retrospectively ECG-gated and nongated MDCT of the chest in an emergency setting regarding workflow, image quality, and diagnostic certainty

PURPOSE

This study aims to assess the influence of ECG-gated acquisition on workflow and to compare image quality and diagnostic certainty for retrospectively ECG-gated and nongated multidetector computed tomography of the chest in the emergency suite.

MATERIALS AND METHODS

Thirty-two consecutive patients were referred for both an ECG-gated and a nongated CT to rule out traumatic thoracic injury (n=15) or acute aortic dissection (n=17). The time from the start of the transportation from the emergency suite to the CT room until the start of the CT scan was recorded. Using a scoring system, the image quality of axial images and multiplanar reformats, the presence of disease, and the subjective diagnostic certainty were assessed with regard to the vascular structures, the bone structures, and the lung parenchyma.

RESULTS

The time needed for transportation and patient preparation was 12.1+/-1.7 min (8.1-14.5 min). The motion artifacts of the thoracic aorta and the supra-aortic vessels were significantly reduced in the ECG-gated data acquisition compared with the nongated technique (P<0.001). Subjective diagnostic certainty for assessment of the aorta was significantly better using ECG gating. The image quality of the lung parenchyma (P<0.005), the spine (P<0.005), and the ribs (P<0.002) was inferior in the ECG-gated data sets but did not compromise the detection rate of traumatic lesions and fractures.

CONCLUSION

Performing ECG gating in the emergency room did not slow down the diagnostic workup. ECG-gated acquisition performed better in the assessment of the aorta, but image quality for lung and bone structures was slightly reduced. Further studies are required to assess the influence of the imaging technique on the diagnostic outcome.

Traumatische Aortenverletzungen bei polytraumatisierten Patienten

Herein we report our results of treatment of traumatic aortic ruptures in severely injured patients with either open surgery or endovascular stent graft repair. Data were analyzed retrospectively from the trauma registry of the DGU (Deutsche Gesellschaft fur Unfallchirurgie) over a time period from 1993 through 2002. All patients with traumatic rupture of the aorta were included and analyzed for injury severity (ISS), blood pressure (mmHg), hemoglobin (mg/%), and AIS (Abbreviated Injury Score) of the thoracic, abdominal, and upper extremity regions. Patients treated between 1998 and 2002 were further examined (operation within 24 h, duration of intervention, blood transfusion, and lethality with regard to either open surgical or endoluminal stent graft repair). Of 14,110 patients, 100 (0.7%) suffered from acute aortic rupture. Mean age was 38 years (+/-19) with an inhospital lethality of 39% (n=39). Mean ISS was 41 (+/-14); 36 patients were treated by open surgery and 5 patients by a stent-assisted endoluminal procedure. Lethality was 17% for open surgery and 0% for stent graft repair. Endovascular approach to traumatic rupture of the aorta is feasible and safe. It has been shown to reduce inhospital lethality and may offer an alternative to open surgery for severely injured patients.

Thoracic aortic injury in motor vehicle crashes: the effect of impact direction, side of body struck, and seat belt use

BACKGROUND

Using in-depth, real-world motor vehicle crash data from the United States and the United Kingdom, we aimed to assess the incidence and risk factors associated with thoracic aorta injuries.

METHODS

De-identified National Automotive Sampling System Crashworthiness Data System (U.S.) and Co-operative Crash Injury Study (U.K.) data formed the basis of this retrospective analysis. Logistic regression was used to assess the level of risk of thoracic aorta injury associated with impact direction, seat belt use and, given the asymmetry of the thoracic cavity, whether being struck toward the left side of the body was associated with increased risk in side-impact crashes.

RESULTS

A total of 13,436 U.S. and 3,756 U.K. drivers and front seat passengers were analyzed. The incidence of thoracic aorta injury in the U.S. and U.K. samples was 1.5% (n = 197) and 1.9% (n = 70), respectively. The risk was higher for occupants seated on the side closest to the impact than for occupants involved in frontal impact crashes. This was the case irrespective of whether the force was applied toward the left (belted: relative risk [RR], 4.6; 95% confidence interval [CI], 2.9-7.1; p < 0.001) or the right side (belted: RR, 2.6; 95% CI, 1.4-5.1; p < 0.004) of the occupant's body. For occupants involved in side-impact crashes, there was no difference in the risk of thoracic aorta injury whether the impacting force was applied toward the left or toward the right side of the occupant's body. Seat belt use provided a protective benefit such that the risk of thoracic aorta injury among unbelted occupants was three times higher than among belted occupants (RR, 3.0; 95% CI, 2.2-4.3; p < 0.001); however, the benefit varied across impact direction. Thoracic aorta injuries were found to be associated with high impact severity, and being struck by a sports utility vehicle relative to a passenger vehicle (RR, 1.7; 95% CI, 1.2-2.3; p = 0.001).

CONCLUSION

Aortic injuries have been conventionally associated with frontal impacts. However, emergency clinicians should be aware that occupants of side-impact crashes are at greater risk, particularly if the occupant was unbelted and involved in a crash of high impact severity.

Change in Velocity and Energy Dissipation on Impact in Motor Vehicle Crashes as a Function of the Direction of Crash: Key Factors in the Production of Thoracic Aortic Injuries, Their Pattern of Associated Injuries and Patient Survival A Crash Injury Research Engineering Network (CIREN) Study

OBJECTIVE

To examine the effect of change in velocity (MV) and energy dissipation (IE) on impact, above and below the test levels for federal motor vehicle crash (MVC) safety standards, on the incidence of aortic injury (AI) and its mortality and associated injury patterns in frontal (F) and lateral (L) MVCs. Comparison of 80 AI and 796 non-AI patients of AIS=3.

METHODS

Eight hundred seventy-six MVC adult drivers or front-seat passengers (552 F and 324 L) evaluated by 10 Level I CIREN study Trauma Centers together with vehicle and crash scene engineering reconstruction. Patient seatbelt and/or airbag use correlated with clinical or autopsy findings.

RESULTS

In AI, 63% of cases were dead at the scene and only 16% survived to leave hospital. The relation between IE dissipated in the MVC and the DeltaV on impact was exponential as DeltaV increased, but the rise in IE for a given DeltaV was greater in LMVC than in FMVC (p <0.05). A more rapid rise in IE/DeltaV occurred above the mean DeltaV of 48 +/- 19.7 kph (30 mph) in FMVC and above the mean DeltaV of 36 +/- 16.2 kph (23 mph) in LMVC. As DeltaV increased above these means, 65% of 46 FMVC aortic injuries (AIs) and 64% of 34 LMVC AIs occurred. In AI patients there was evidence of focusing of the point of IE impact on the upper chest with a higher incidence of rib1-4 fractures than in non-AI (p <0.01) and more brain, heart, lung and spleen injuries (p <0.01) consequent to lower seatbelt use (p <0.01), but LMVC also had more pelvic fx (p <0.05). Airbags + seatbelts in FMVC and seatbelts in LMVC reduced mortality (p <0.05) Comparison of AI incidence in three successive 4-year vehicle model year periods showed a progressive decrease as new safety devices were introduced (p < 0.05).

CONCLUSIONS

The implications for AI of the focused IE at the upper chest suggest a probable mechanism for MVC AI with the pressurized aortic arch acting as the long arm of a lever system with the fulcrum at the subclavian artery, producing maximum torsional strain at the short arm of the isthmus where 75% of the AIs occurred. AI mortality is also influenced by the associated injuries. To develop more effective safety systems to prevent AI, MVC safety testing with airbags and seatbelts should be carried out at DeltaVs of 1 SD above means for FMVC and LMVC.

Vascular Emergencies of the Thorax after Blunt and Iatrogenic Trauma: Multi–Detector Row CT and Three-dimensional Imaging

Multi-detector row computed tomographic (CT) angiography is an effective modality for vascular imaging in the thorax. It allows acquisition of high-resolution data sets during a single breath hold, making it the preferred method for evaluation of patients with acute vascular disease. In contrast to conventional angiography, multirow CT angiography not only depicts the vessels but also allows assessment of adjacent structures. Multirow CT angiography with two- and three-dimensional reformation can be used to diagnose vascular emergencies of the thorax after blunt and iatrogenic trauma. These include incomplete and complete aortic rupture; traumatic aortic dissection; arterial dissection and rupture after minor trauma in patients with Ehlers-Danlos syndrome; traumatic intramural hematoma; pseudoaneurysm after endovascular repair; injuries due to Swan-Ganz catheters; complications of central venous cannulation, pacemaker implantation, and percutaneous pericardial drainage; and foreign-body embolism. The diagnoses can be established with multirow CT angiography in the emergency department. Thus, the time to diagnosis can be considerably decreased by obviating conventional angiography. Knowledge of the CT findings in various vascular conditions is essential to make use of multirow CT angiography in combination with two- and three-dimensional reformation as an efficient and accurate diagnostic tool in emergency radiology.

Multidetector row computed tomography of the aorta and peripheral arteries

MDCT represents a significant advance on SDCT and the advantages it brings are particularly clear in CTA applications. It allows cost effective assessment of longer segments of vascular territories to be imaged with higher spatial, contrast, and temporal resolution. It has replaced SDCT as the new CT standard and its technical abilities are rapidly approaching the temporal resolution of EBCT. With 3-D post processing tools its main benefit is in imaging studies customized to the patient's pathology, with greater measurement accuracy and reliable longitudinal assessment. MDCTA is increasingly applied not to individual vascular territories but to a complete assessment dictated by the pathology, such as the entire aorta and branch vessels in aneurysm evaluation and the aorta and the coronary arteries in dissection cases or the vascular and non-vascular chest in acute chest pain. Greater accuracy of vessel assessment will lead to a refinement of interventional and surgical techniques for an individual patient and facilitates conservative management of conditions that can be reliably monitored non-invasively and the development of intervention criteria. MDCTA will continue to increase its major role in peripheral vascular evaluation in the future though its reliability in assessing small vessels below the knee and in the foot remains to be conclusively proven to obviate the need for diagnostic catheter angiography.

Development of a computer model to predict aortic rupture due to impact loading

Aortic injuries during blunt thoracic impacts can lead to life threatening hemorrhagic shock and potential exsanguination. Experimental approaches designed to study the mechanism of aortic rupture such as the testing of cadavers is not only expensive and time consuming, but has also been relatively unsuccessful. The objective of this study was to develop a computer model and to use it to predict modes of loading that are most likely to produce aortic ruptures. Previously, a 3D finite element model of the human thorax was developed and validated against data obtained from lateral pendulum tests. The model included a detailed description of the heart, lungs, rib cage, sternum, spine, diaphragm, major blood vessels and intercostal muscles. However, the aorta was modeled as a hollow tube using shell elements with no fluid within, and its material properties were assumed to be linear and isotropic. In this study fluid elements representing blood have been incorporated into the model in order to simulate pressure changes inside the aorta due to impact. The current model was globally validated against experimental data published in the literature for both frontal and lateral pendulum impact tests. Simulations of the validated model for thoracic impacts from a number of directions indicate that the ligamentum arteriosum, subclavian artery, parietal pleura and pressure changes within the aorta are factors that could influence aortic rupture. The model suggests that a right-sided impact to the chest is potentially more hazardous with respect to aortic rupture than any other impact direction simulated in this study. The aortic isthmus was the most likely site of aortic rupture regardless of impact direction. The reader is cautioned that this model could only be validated on a global scale. Validation of the kinematics and dynamics of the aorta at the local level could not be done due to a lack of experimental data. It is hoped that this model will be used to design experiments that can reproduce field relevant aortic ruptures in the laboratory. Only after such experiments have been run, can local validation be examined and the model judged to be acceptable or unacceptable.

[Blunt force rupture of the thoracic aorta and diaphragm: an unusual association]

The aim of this study was to report two cases of rupture of the right hemidiaphragm with intra-thoracic liver hernia, associated with a traumatic aortic disruption. These two lesions followed traffic accidents, and were both treated separately. Both patients had a long-term favourable progression. Association of these two lesions is particularly rare: fewer than 50 cases have been previously described in an extensive review of the literature. CT-scan seems to be particularly efficient in diagnosis, even if less efficient than other more specific explorations. The order of surgical management is guided by the physical examination, and especially by abdominal emergency.

Blunt and penetrating trauma of the thoracic aorta and aortic arch branches: an autopsy study

BACKGROUND

Due to the highly lethal nature of trauma of the thoracic aorta and aortic arch branches (TA-AAB), autopsy studies are essential for the investigation of its epidemiologic characteristics.

METHODS

The reports of 11,446 consecutive medicolegal autopsies were reviewed. Among 1,980 injury-related fatalities, 251 victims (12.7%) with 302 TA-AAB injuries were found. Several trauma variables were recorded and their relations were examined.

RESULTS

Blunt TA-AAB injuries were recorded in 86.4% of the victims. They were located mainly at the aortic isthmus and distal descending thoracic aorta and were accompanied to a great extent by extrathoracic trauma. The vast majority of penetrating lacerations were located at the ascending aorta, arch, and arch branches and were mostly associated with other lethal intrathoracic injuries. All penetrating trauma victims died before reaching the hospital, whereas 5.5% of the blunt trauma victims were admitted to the hospital alive.

CONCLUSION

Major differences between blunt and penetrating TA-AAB injuries were revealed, regarding their location, patterns of concomitant injuries, and victims' survival time. Patients injured in motor vehicle crashes, as opposed to various other causes of trauma, were found to have the best chances of reaching the hospital alive.

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.

Thoracic aortic injury: how predictive is mechanism and is chest computed tomography a reliable screening tool? A prospective study of 1,561 patients

BACKGROUND

Thoracic aortic injury (TAI) is a devastating condition in which prompt recognition can obviate morbidity and mortality. It is a long-held belief that TAI is more likely when there is a "major mechanism of injury." The purposes of this prospective study were to determine mechanism characteristics that are predictive of TAI and to evaluate chest computed tomography (CT) as a screening tool for TAI.

METHODS

Over a 5 1/2 year period, blunt chest trauma patients at two Level I trauma centers were evaluated for potential TAI. Patients were assigned mechanism and radiograph scores from 1 (low suspicion for TAI) to 5 (very high suspicion for TAI). Immediate aortography was obtained when suspicion for TAI was very high. The remaining patients were evaluated with contrast-enhanced chest CT. Confirmatory aortography was obtained on all positive chest CT scans and on all patients with mechanism scores of 4 or 5 even if the CT was negative. Mechanism and radiographic data were correlated with the results of aortic imaging.

RESULTS

Of the 1,561 patients evaluated for TAI, 30 aortic injuries were found. The assessment of mechanism was imperfect with a reliance on often incomplete and subjective data. The subjective mechanism score proved to be the most useful predictor of TAI. Radiographic scores were useful but insensitive for intimal injuries. Computed tomography was found to have 100% and 100% NPV for TAI.

CONCLUSION

Considering the inherent difficulties in identifying patients at risk for TAI and the effectiveness of chest CT as a screening tool for aortic injury, we recommend liberal use of chest CT in blunt chest trauma. Guidelines for determining the need for aortic imaging are outlined.

Aortic transection

BACKGROUND

Traumatic aortic transection is uncommon in those trauma patients reaching hospital alive.

METHODS

The Victorian Major Trauma Study (VMTS) received data from 25 hospitals in Victoria, a State of 4.4 million people, and identified 1874 patients with blunt trauma and Injury Severity Score (ISS) greater than 15 over a 2-year period (1 March 1992-28 February 1993 and 1 May 1994-30 April 1995). The Federal Office of Road Safety (FORS) examined coronial data from 1 January 1992 to 31 December 1992. These studies allowed a retrospective, population-based review of experience with aortic transection.

RESULTS

The VMTS identified 19 patients who reached hospital, with signs of life at the scene of the accident, during a 2-year period. Of these, 8 left hospital alive: 4 without disability and 4 with disability related to non-thoracic injury. The annual incidence of aortic transection for the State, based on FORS data, was 13 per 1000000, lower than other reported studies. Review of the management of patients in hospital confirmed the usefulness of initial chest X-ray in diagnosis and the high incidence of associated injury.

CONCLUSIONS

The study raises a number of issues, including the question of direct referral of patients with severe chest injury to hospitals with cardiothoracic facilities, increased use of transoesophageal echocardiography in diagnosis and increased use of immediate laparotomy and thoracotomy in certain patients.

Lateral impact motor vehicle collisions: significant cause of blunt traumatic rupture of the thoracic aorta

BACKGROUND

This study was undertaken to determine the relationship between traumatic rupture of the thoracic aorta (TRA) and the direction of impact at the time of motor vehicle crash.

METHODS

Retrospective review of TRA patients from two different databases over a 4.5-year period (January 1, 1991 to June 30, 1995): (1) Ontario Coroner's Office records of motor vehicle deaths from Metropolitan Toronto, and (2) the trauma registries of Sunnybrook Health Science Centre and St. Michael's Hospital in Metropolitan Toronto.

RESULTS

Ninety-seven patients (81 from the coroner's database and 16 from the adult trauma unit registries) sustained traumatic rupture of the thoracic aorta. Forty-eight cases (49.5%) were a result of lateral impact crashes. Twenty-eight drivers (22 ipsilateral and six contralateral) and 20 passengers (16 ipsilateral and four contralateral) sustained TRA from lateral impact crashes. Ninety-one TRAs (94%) occurred at the peri-isthmic region.

CONCLUSION

Lateral impact crashes are a significant cause of TRA. Traumatic rupture of the aorta should be considered with a high index of suspicion after serious lateral impact crashes, just as physicians now consider patients at high risk of TRA after serious frontal impact crashes.

Thoracic aorta injuries: management and outcome of 144 patients

Rupture of the thoracic aorta from blunt injury is often lethal. Methods of operative repair vary, based on the surgeon's preference and circumstances. The primary hypothesis of this study was that operative management choices would correlate with outcome. Data on demographics, injury mechanism, initial evaluation, diagnostic procedures, operative treatment, and outcome were obtained from chart review at the state's eight trauma centers. Rates of paraplegia and survival were compared for different methods of operative repair. Of 63,507 hospitalized trauma patients, 144 patients sustained thoracic aortic injury (incidence = 0.23%). Sixty-four died (44.1%), most of whom died in the emergency department (26) or the operating room (12). Eighty-six patients had complete operative data for analysis, including cross-clamp time and methods of repair. No patient in the group with a cross-clamp time of less than 35 minutes developed paraplegia (p = 0.02). For the patients with longer cross-clamp times, 6 of 14 patients (42.9%) undergoing clamp and sew repair developed paraplegia, as compared to 2 of 37 patients (5.4%) repaired on bypass (p = 0.005). This study suggests that the rate of paraplegia after repair of thoracic aortic injury can be minimized with short cross-clamp times or the use of bypass when long cross-clamp times can be anticipated.

Routine transesophageal echocardiography for the diagnosis of aortic disruption in trauma patients without enlarged mediastinum

OBJECTIVE

To assess the value of routine transesophageal echocardiography (TEE) in diagnosing traumatic disruption of the aorta (TDA) in trauma patients presenting without enlarged mediastinum on chest x-ray films.

DESIGN

Prospective study.

MATERIALS AND METHODS

TEE was routinely performed to exclude the presence of TDA in patients who sustained severe trauma secondary to abrupt deceleration collisions and presented with an upper mediastinum of fewer than 8 cm on supine chest x-ray films. Patients were divided into two groups according to the presence (group I) or absence (group II) of mediastinal hematoma diagnosed during TEE examination. Radiographic signs regarded as indicators of the presence of TDA were evaluated in both groups.

RESULTS

Among the 40 consecutive patients studied, TEE demonstrated two cases of TDA associated with a mediastinal hematoma that were confirmed by both aortography and surgery. One of the patients had a normal mediastinum on presentation chest x-ray films, and the other only exhibited a blurred aortic knob. Radiographic mediastinal abnormalities suggestive of TDA were observed in 13 patients, but chest x-ray films were unremarkable in 12 patients. Twenty patients had multiple rib fractures. The frequency of chest radiographic abnormalities was not significantly higher in group I (n = 6) when compared with group II patients (n = 34). TEE examination demonstrated a normal thoracic aorta in 35 patients and was nondiagnostic in 3 patients (normal aortography).

CONCLUSION

TEE should be routinely performed in victims of violent deceleration collisions, even in patients presenting apparently normal mediastinum on supine chest radiography.

Side impact motor vehicular crashes: patterns of injury

Side impact collisions represent a serious risk for injury for motor vehicle occupants. In 1992 side impact collisions were found in approximately 20% of all fatal motor vehicle crashes. This type of collision provides less protection to the occupants and is associated with a specific pattern of injuries. Because elderly drivers are frequently involved in side impact collisions, they are especially at risk for major trauma.

Blunt diaphragmatic and thoracic aortic rupture: an emerging injury complex

Although both blunt diaphragmatic rupture (BDR) and thoracic aortic rupture (TAR) have been extensively discussed, the association of both injuries has been infrequently mentioned. The purpose of this study was to examine the current prevalence and clinical characteristics of combined BDR and TAR at an adult regional trauma unit. Among 3,886 trauma victims, 69 (1.8%) had a BDR and 44 (1.1%), a TAR. Seven patients (10% of all patients with a BDR) had both injuries. All 7 were victims of motor vehicle crashes and had a mean Injury Severity Score of 35. All TARs were just distal to the origin of the left subclavian artery. Five patients underwent repair of both injuries and survived, 1 patient had only the BDR repaired and survived, and 1 died during emergency thoracotomy, for a survival rate of 86%. Five patients had laparotomy and repair of the BDR in the presence of an unrepaired TAR. The TARs were repaired by the clamp-and-sew technique, three of them with primary repair and two with interposition tube grafts. Concomitant BDR and TAR appears to be an emerging injury complex with both diagnostic and therapeutic challenges. The presence of BDR demands a rigorous search for associated TAR.