Traumatic rupture of thoracic aorta in real-world motor vehicle crashes

Biomechanical study on the effect of atherosclerosis on the vulnerability of thoracic aorta, and it's role in the development of traumatic aorta injury

Traumatic aorta injury (TAI) is the second most common traumatic cause of death preceded only by head injuries, being responsible for 5% to 30% of all mortalities in high-speed deceleration injuries. Multiple external factors might play a role such as impact speed, impact direction, occupant location, and presence or lack of restraining safety mechanism. Apart from these external factors, also human biological factors can influence its development. Based on the data of scientific literature, age clearly plays a role in suffering TAI, but the role of atherosclerosis-as a disease affecting the structure of the aorta-is unknown. Biomechanical properties of tissue samples of 104 aorta specimens removed during the autopsy from the posterior (Group 'A') and lateral wall (Group 'B') of descending aorta were analyzed. Specimens were examined by a Zwick/Roell Z5.0 biaxial tester. The Young's modulus (E (MPa)) was calculated using a linear regression procedure where the base of the elongation was the parallel length of the sample, the achieved maximal force (Fmax (N)), the elongation at the time of Fmax (Lmax (mm)), the force at the beginning of rupture (Fbreak (N)), the elongation at the time of Fbreak (Lbreak (mm)) were registered. Specimens were categorized based on macroscopic and microscopic appearance. In the posterior (A) samples the difference between Lbreak (p<0.001) and Lmax (p<0.001) was significant between the macroscopic group. Lbreak (p = 0.009) and Lmax (p = 0.003) showed similar pattern in the lateral (B) samples. Comparing the histological groups by the measured parameters (Fmax, Lmax, Fbreak, Lbreak) showed a significant difference in the means (p<0.001, p = 0.003, p<0.001 respectively). The study demonstrated that atherosclerosis decreases the resistance of the aorta. The rupture occurs at lower force (Fmax and Fbreak), and at shorter elongation (Lmax and Lbreak) in case of the presence of atherosclerosis. This effect is most substantial if calcification is present: the resistance of aorta affected by calcification is only two-thirds on average compared to aorta affected by the early phase of atherosclerosis. This phenomenon can be clearly explained by the weakening structure of the tunica intima.

Concurrent Thoracic Endovascular Aortic Repair and Liver Transplant: Multidisciplinary Management of Multiple Posttraumatic Lesions

Association of thoracic and abdominal injuries in patients with major trauma is common. Under emergency conditions, it is often difficult to promptly perform a certain diagnosis and identify treatment priorities of life-threatening lesions. We present the case of a young man with combined thoracic and abdominal injuries after a motorcycle accident. Primary evaluation through echography and X-ray showed fluid within the hepatorenal recess and an enlarged mediastinum. Volume load, blood transfusions, and vasoactive agents were initiated to sustain circulation. Despite hemodynamic instability, we decided to perform computed tomographic angiography (CTA) scan that revealed a high-grade traumatic aortic pseudoaneurysm, multiple and severe areas of liver contusion, and a small amount of hemoperitoneum, without active bleeding spots. The patient was successfully submitted to thoracic endovascular aortic repair (TEVAR). Immediately after the end of the successful TEVAR, signs of massive abdominal bleeding revealed. Immediate explorative laparotomy was performed showing massive hepatic hemorrhage. After liver packing and Pringle's maneuver, control of bleeding was lastly obtained with hemostatic devices and selective cross-clamping of the right hepatic artery. The patient was then transferred to intensive care unit where, despite absence of further hemorrhage, hemodynamic instability, anuria, severe lactic acidosis together with liver necrosis indices appeared. A new CTA demonstrated massive parenchymal disruption within the right lobe of the liver and multiple hematomas in the left lobe. Considering the high-grade lesions of the hepatic vascular tree and liver failure, patient was listed for emergency liver transplantation (LT). LT occurred few hours later, and patient's clinical conditions rapidly improved even if the subsequent clinical course was characterized by a severe fungal infection because of immunosuppression. Evaluation of life-threatening lesions and treatment priorities, availability of different excellence skills, and multidisciplinary collaboration have a key role to achieve clinical success in such severe cases.

Finite Element Analysis of the Mechanism of Traumatic Aortic Rupture (TAR)

As many as 80% of patients with TAR die on the spot while out of those reaching a hospital, 30% would die within 24 hours. Thus, it is essential to better understand and prevent this injury. The exact mechanics of TAR are unknown. Although most researchers approve it as a common-sense deceleration injury, the exact detailed mechanism of TRA still remains unidentified. In this work, a deceleration mechanism of TAR was carried out using finite element analysis (FEA). The FE analysis aimed to predict internal kinematics of the aorta and assist to comprehend the mechanism of aorta injury. The model contains the heart, lungs, thoracic aorta vessel, and rib cage. High-resolution computerized tomography (HR CT scan) was used to provide pictures that were reconstructed by MIMICS software. ANSYS FE simulation was carried out to investigate the behavior of the aorta in the thoracic interior after deceleration occurred during a car crash. The finite element analysis indicated that maximum stress and strain applied to the aorta were from 5.4819e5 to 2.614e6 Pa and 0.21048 to 0.62676, respectively, in the Y-direction when the initial velocity increased from 10 to 25 m/s. Furthermore, in the X-direction when the velocity changed from 15 to 25 m/s, the stress and strain values increased from 5.17771e5 to 2.3128e6 and from 0.22445 to 0.618, respectively.

Biomechanics of aortic wall failure with a focus on dissection and aneurysm: A review

Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. The maximum diameter criterion, typically used for aneurysm rupture risk estimations, has been challenged by more sophisticated biomechanically motivated models in the past. Although these models are very helpful for the clinicians in decision-making, they do not attempt to capture material failure. Following a short overview of the microstructure of the aorta, we analyze the failure mechanisms involved in the dissection and rupture by considering also traumatic rupture. We continue with a literature review of experimental studies relevant to quantify tissue strength. More specifically, we summarize more extensively uniaxial tensile, bulge inflation and peeling tests, and we also specify trouser, direct tension and in-plane shear tests. Finally we analyze biomechanically motivated models to predict rupture risk. Based on the findings of the reviewed studies and the rather large variations in tissue strength, we propose that an appropriate material failure criterion for aortic tissues should also reflect the microstructure in order to be effective. STATEMENT OF SIGNIFICANCE: Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. Despite the advances in medical, biomedical and biomechanical research, the mortality rates of aneurysms and dissections remain high. The present review article summarizes experimental studies that quantify the aortic wall strength and it discusses biomechanically motivated models to predict rupture risk. We identified contradictory observations and a large variation within and between data sets, which may be due to biological variations, different sample sizes, differences in experimental protocols, etc. Based on the findings of the reviewed literature and the rather large variations in tissue strength, it is proposed that an appropriate criterion for aortic failure should also reflect the microstructure.

Higher Prevalence of Bovine Aortic Arch Configuration in Patients Undergoing Blunt Isthmic Aortic Trauma Repair

BACKGROUND

The prevalence of a bovine aortic arch configuration is higher in patients treated for thoracic aortic aneurysms and type B dissection; its prevalence in aortic isthmic trauma has not been described.

METHODS

A case control study was performed comparing consecutive patients treated at our institution for acute isthmic aortic transection after blunt trauma between 2002 and 2019 and a control group of consecutive sex-matched individuals undergoing imaging for nonaortic disease. Imaging and clinical findings were reviewed. Subjects were divided into bovine and nonbovine groups and prevalence was compared. The length of the aortic segment between the left subclavian artery (LSA) and the next proximal great vessel was measured in the control population and a comparison was performed between bovine and nonbovine aortic arch subjects.

RESULTS

Thirty-three consecutive (30 male) patients were reviewed, 66 individuals (60 male) were included in the control group. A higher incidence of bovine arch in trauma patients was found: 57.6% vs. 34.8% (P = 0.007). The median (range, mm) and mean (SD) distance between the bovine trunk and the LSA were 13 mm (2-27) and 12.4 mm (5.9), respectively, compared with 5 mm (1-27) and 7.8 mm (6.1) between the left common carotid and LSA in nonbovine aortic arches (P < 0.005).

CONCLUSION

A higher incidence of bovine arch in patients reaching out for surgical treatment for traumatic isthmic aortic transection was found in our population. Clinical interpretation of this finding can lead to several alternatives. Confirmation with larger series and data on prevalence of this anatomic variation in nonsurvivors is needed to provide a better understanding of this finding.

Pattern Recognition: A Mechanism-based Approach to Injury Detection after Motor Vehicle Collisions

Motor vehicle collisions cause substantial mortality, morbidity, and expense worldwide. Certain types of injuries are more likely to result from frontal versus side-impact collisions, and knowledge of these specific patterns and why they occur aids in accurate and efficient diagnosis of traumatic injuries. Although the proper use of seat belts decreases crash-related mortality during frontal impact, certain injury patterns to the torso are directly attributed to restraint use. The spectrum of seat belt-related injuries ranges from mild skin and soft-tissue contusions to traumatic bowel injuries and unstable spine injuries that require surgery. Impact with the steering wheel or windshield during a frontal crash can cause characteristic injuries to the head, neck, torso, and distal upper extremity. Steering wheel deformity is an independent predictor of serious thoracic and abdominal injury among front-seat passengers. Impact of a flexed knee with the dashboard during a frontal collision can cause knee, thigh, and hip injuries. Distal lower extremity injuries are encountered frequently when the floorboard is driven into the foot. Lateral impact crashes often result in traumatic brain, thoracic, abdominal, and pelvic injuries, which are more often fatal to occupants on the side of the impact. The specific mechanism-based injury patterns are reviewed to establish a structured systematic search pattern that enables the radiologist to identify traumatic injuries with greater accuracy and speed, thereby improving the care of patients who experience acute trauma. ^©RSNA, 2019 See discussion on this article by Ballard and Mellnick .

Traumatic aortic injury presenting to an adult major trauma centre

Introduction

Traumatic aortic injury is an uncommon condition. Timely diagnosis may enable early haemostatic resuscitation, essential to prevent worsening of the injury prior to definitive management. The aim of this study was to assess the utility of initial vital signs and presenting clinical characteristics to confirm or rule out aortic injury.

Methods

A retrospective review of patients from The Alfred Trauma Registry was conducted. Patients presenting between January 2006 and July 2014 and diagnosed with aortic injury were identified. Demographics and presenting clinical characteristics were extracted. Sensitivity of individual clinical variables for the detection of aortic injury was calculated.

Results

There were 77 patients identified with aortic injury, with an in-hospital mortality rate of 19.5% (95% CI: 10.6–28.3%). Of these, 68 (88.3%) patients presented after high-energy blunt mechanisms. Clinical signs and early chest X-ray findings were poorly sensitive to detect aortic injury. Patients who presented with hypotension had a greater severity of aortic injury, more commonly had associated abnormal investigation findings and were more likely to require blood products and inotropic agents (p < 0.05). However, sensitivity of initial hypotension to rule out aortic injury was 39.0% (95% CI: 28.1–49.9%).

Conclusions

The diagnosis of aortic injury was uncommon in hospital. Most injuries were secondary to high-velocity road traffic crashes or high falls. Clinical signs were not adequately sensitive to be used for the exclusion of aortic injury. We recommend a high degree of clinical suspicion and liberal imaging among cases where aortic injury is possible.

Vascular geometry as a risk factor for non-penetrating traumatic injuries of the aortic arch

PURPOSE

To assess biomechanical factors in aortic arch geometry contributing to the development of non-penetrating aortic arch injury (NAAI) in multiply injured patients with an Injury Severity Score (ISS) ≥ 16.

MATERIAL AND METHODS

230 consecutive multiply injured trauma patients with an ISS ≥ 16 admitted to our Level-I trauma center during a consecutive 24-month period were prospectively included of whom 13 presented with NAAI (5.7%). Standardized whole-body CT in a 2x128-detector-row scanner included a head-and-neck CTA. Aortic arch diameters, width, height, angles and thoracic width and height were measured in individuals with NAAI and ISS-, sex-, age-, and trauma mechanism-matched controls.

RESULTS

There was no difference between groups regarding sex, age, ISS, and aortic diameters. The aortic arch angle in individuals with NAAI (71.3° ± 14.9°) was larger than in healthy control (60.7° ± 8.6°; p*<0.05). In patients with NAAI, the distance between ascendent and descendent aorta was larger (5.2 cm ± 1.9 cm) than in control (2.8 ± 0.5 cm; ***p<0.001). The aortic arch is higher above tracheal bifurcation in NAAI (3.6 cm ± 0.6 cm) than in matched control (2.4 cm ± 0.3 cm; ***p<0.001). Accordingly, the area under the aortic arch, calculated as half of an eliptic shape, is significantly larger in patients with NAAI (15.0 cm2 ± 6.5 cm2) when compared to age- and sex-matched controls without NAAI (5.5 cm2 ± 1.3 cm2; ***p<0.001).

CONCLUSION

Besides the magnitude of deceleration and direction of impact, width and height of the aortic arch are the 3rd and 4th factor directly contributing to the risk of developing traumatic NAAI in severely injured patients.

Investigation of inhomogeneous and anisotropic material behavior of porcine thoracic aorta using nano-indentation tests

This study investigates the inhomogeneity and anisotropy of porcine descending thoracic aorta in three dimensions using a custom-made nano-indentation technique and a quasi-linear viscoelastic modeling approach. The indentation tests were conducted in axial, circumferential, and radial orientations with about 100 μm spatial resolution. The ratio of the elastic moduli obtained in different orientations was used to quantify the tissue local anisotropy. The distal sections were generally stiffer than the proximal ones in both axial and circumferential indentations. Four distinct layers were identified across the thickness with significantly different mechanical properties. The stiffness of the medial quadrant was significantly lower than all other quadrants in axial indentation. The anisotropic behavior of the tissue was more pronounced in the lateral quadrant of the distal sections. The results of this study can be used to better understand the mechanisms of aorta deformation and improve the spatial accuracy of computational models of aorta.

Open Repair Versus Thoracic Endovascular Aortic Repair in Multiple-Injured Patients: Observations From a Level-1 Trauma Center

Background:

Blunt trauma of the thoracic aorta is a rare but potentially life-threatening entity. Intimal tears are a domain of non-operative management, whereas all other types of lesions should be repaired urgently. There is now a clear trend favoring minimally invasive stent grafting over open surgical repair.

Objectives:

The aim of the present study was to retrospectively evaluate the mortality and morbidity with either treatment option. Therefore, a retrospective observational study was performed to compare two different treatment methods at two different time periods at one trauma center.

Patients and Methods:

Between 1977 and 2012, all severely injured patients referred to our level 1 trauma center were screened for blunt aortic injuries. We compared baseline characteristics, 30-day and overall mortality, morbidity, duration of intensive care treatment, procedure time, and transfusion of packed red blood between patients who underwent open surgical or stent repair.

Results:

During the observation period, 45 blunt aortic injuries were recorded. The average Injury Severity Score (ISS) was 41.8 (range 29 - 68). Twenty-five patients underwent Open Repair (OR), and another 20 patients were scheduled to emergency stent grafting. The 30-day mortality in the surgical and stent groups were 5/25 (20%) and 2/20 (10%), respectively. The average time for open surgery was 151 minutes; the mean time for stent grafting was 67 minutes (P = 0.001). Postoperative stay on the intensive care unit was between one and 59 days (median 10) in group one and between four and 50 days in group two (median 26)(P = 0.03). Patients undergoing OR required transfusion of 6.0 units of packed red cells in median; patients undergoing stent grafting required a median of 2.0 units of packed red cells (P < 0.001). In the stent grafting group, 30-day mortality was 10% (2/20).

Conclusions:

Due to more sophisticated diagnostic tools and surgical approaches, mortality and morbidity of blunt aortic injuries were significantly reduced over the years compared to thoracic endovascular aortic repair and OR over two different time periods.

Etiology of fatal thoracic aortic injuries: Secondary data analysis

OBJECTIVES

Motor vehicle crashes remain a leading cause of death in the United States (US). Thoracic aortic dissection due to blunt trauma remains a major injury mechanism, and up to 90% of these injuries result in death on the scene. The objective of this study is to understand the modern risk factors and etiology of fatal thoracic aortic injuries in the current US fleet.

METHODS

Using a unique, linked, Fatality Analysis Reporting System (FARS) and Multiple Cause of Death (MCOD) database from 2000-2010, 144,169 drivers over 16 years of age who suffered fatal injuries were identified. The merged database provides an unparalleled fidelity for identifying thoracic aortic injuries due to motor vehicle accidents. Thoracic aortic injuries were defined by ICD-10 codes S250. Univariate and multivariate logistic regression models for presence of any thoracic aortic injuries were fitted. Age, gender, BMI weight categories, vehicle class, model year, crash type/direction, severity of crash damage, airbag deployment location, and seatbelt use, fatal injury codes, and location of injury were considered. Odds ratios (OR) and corresponding 95% confidence intervals (95%CI) are calculated.

RESULTS

There were 2953 deaths (2.10%) related to thoracic aortic injuries that met the inclusion criteria. Nearside crashes were associated with an increased odds (OR = 1.42, 1.1-1.83), while rollover crashes (OR =.44,.29-.66) were associated with a reduced odds of fatal thoracic aortic injury. Using backward selection on the full multivariate model, the only significant model effects that remained were vehicle type, crash type, body region, and injury type.

CONCLUSIONS

The increased prevalence of fatal thoracic aortic injury in nearside crashes, increasing age, and vehicle type provide some insight into the current US fleet. Important factors, including model year, had significantly lower levels of the injury in univariate analysis, demonstrating the effect of safety improvements in newer model vehicles. Further study of this fatal injury is warranted, including comparisons of those who survive the injury.

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.

Pathology-specific late outcome after endovascular repair of thoracic aorta: a single-centre experience

OBJECTIVES

Endovascular treatment of thoracic aortic lesions appears to be advantageous. However, long-term outcomes remain poorly reported. This retrospective study reported 6-year outcomes of thoracic endovascular aortic repair.

METHODS

A total of 74 patients underwent endovascular thoracic aorta treatments between 1999 and 2007; 13 had thoracic aortic dissections, 19 had traumatic aortic injuries, 35 had aneurysms, 6 had pseudoaneurysms and 1 had a penetrating ulcer. The mean follow-up was 66 months after 30 perioperative days. Yearly follow-ups included computed tomography angiography or magnetic resonance angiography. Patient demographics, mortality, complications and reinterventions were analysed.

RESULTS

The early 30-day mortality and the overall late mortality were 9.5 (7/74) and 37.8% (28/74), respectively. Late mortality was higher in patients with aneurysms than in the other groups (20/35; 57% vs 8/39; 20.5%; P = 0.002). Aortic-related mortality occurred in 5/35 (14%) patients with aneurysms, but not in other groups (P = 0.02). No relationships among late complications were found for traumatic aortic injuries. The most common complication was an endoleak (21/74, 28.4%), which occurred more frequently with aneurysms than other disorders (18/35, 51.4% vs 3/39, 7.7%; P < 0.001). Endoleaks also occurred most frequently in aortic-related deaths (16/69 vs 5/5; P = 0.001). Type 1 endoleaks occurred significantly more often with aneurysms (13/35) than with other disorders (P = 0.004). Reintervention was required in 9 patients (12%); 8 with atherosclerotic aneurysms (8/35; 23%). A false lumen was thrombosed in 54% of dissections (7/13), and shrank in 39% (5/13).

CONCLUSIONS

Long-term outcomes depended on aortic pathology. Aortic aneurysms were the most complicated and caused the highest mortality, probably due to atherosclerotic disease evolution. Patients with traumatic aortic injuries appeared to have the best long-term outcomes.

Acute Traumatic Thoracic Aortic Injury: Considerations and Reflections on the Endovascular Aneurysm Repair

Traumatic rupture of the thoracic aorta is a life-threatening lesion and it occurs in 10 to 30% of fatalities from blunt thoracic trauma and is the second most common cause of death after head injury. Immediate surgery is often characterized by a high mortality and morbidity rate. Delayed repair of traumatic aortic injuries has significant survival benefits and a much lower mortality rate compared with early open repair. Despite developments in operative techniques, there still remains considerable operative mortality and morbidity associated with a surgical approach even if delayed. Endovascular stent grafts for the thoracic aorta represents an alternative to the conventional approach for traumatic aortic rupture. Because of the lower invasivity avoiding thoracotomy and use of heparin, endovascular repair can be applied in acute patients without the risk of destabilizing pulmonary, head or abdominal traumatic lesions. However, despite the good deal of convincing evidence for endovascular treatment for thoracic aortic diseases and for traumatic aortic injuries as a valid and efficacious alternative to surgery, several reports show a variety of late complications of thoracic endografts especially for first-generation stent-grafts. In light of this, is the endovascular treatment really safe, efficacious and free from complications in the long term? This manuscript aims to offer a moment of reflection on this important chapter of aortic pathology.

Blunt thoracic aortic injuries: CT characterisation and treatment outcomes of minor injury

OBJECTIVES

Computed tomography (CT)-defined anatomical differentiation of minor and major blunt traumatic aortic injuries (TAIs) was applied to determine injury grade and management/outcomes in minor TAIs, and if the presence of peri-aortic mediastinal haematoma (MH) correlated with TAI grade.

METHODS

Admission chest CT of blunt TAI cases during 2005-2011 were reviewed by consensus and categorised as major or minor. Minor was defined as pseudoaneurysm <10 % normal aortic lumen, intimal flap or contour abnormality. Presence/absence of MH was determined. Clinical management/outcome was ascertained from medical records.

RESULTS

Of 115 TAIs, 42 were minor (33 with MH, 9 without). Among the 73 with major TAI, 3 had no MH. Twenty-six (62 %) minor TAI patients were managed medically, 12 (29 %) percutaneous stent-grafts, 2 (5 %) died of non-aortic causes and 2 (5 %) underwent surgery. Of 26 managed without intervention, none developed complications from TAI at last clinical or CT follow-up. The relationship between presence/absence of peri-aortic MH and grade of TAI was statistically significant.

CONCLUSIONS

More than a third of multi-detector (MD) CT-diagnosed TAIs were minor. Minor TAIs treated medically were stable at last follow-up, suggesting this is a reasonable initial management approach. Absence of MH cannot be relied upon to exclude minor TAI, indicating the need for careful direct aortic inspection.

KEY POINTS

• MDCT can differentiate minor from major blunt traumatic aortic injuries. • About one-third of MDCT-diagnosed blunt traumatic aortic injuries are minor. • Minor aortic injuries are not necessarily accompanied by mediastinal haemorrhage. • MDCT diagnosis of minor aortic injury supports application of medical management.

Tunable mechanical behavior of synthetic organogels as biofidelic tissue simulants

Solvent-swollen polymer gels can be utilized as mechanical simulants of biological tissues to evaluate protective systems and assess injury mechanisms. However, a key challenge in this application of synthetic materials is mimicking the rate-dependent mechanical response of complex biological tissues. Here, we characterize the mechanical behavior of tissue simulant gel candidates comprising a chemically crosslinked polydimethylsiloxane (PDMS) network loaded with a non-reactive PDMS solvent, and compare this response with that of tissue from murine heart and liver under comparable loading conditions. We first survey the rheological properties of a library of tissue simulant candidates to investigate the effects of solvent loading percentage, reactive functional group stoichiometry, and solvent molecular weight. We then quantify the impact resistance, energy dissipation capacities, and energy dissipation rates via impact indentation for the tissue simulant candidates, as well as for the murine heart and liver. We demonstrate that by tuning these variables the silicone gels can be engineered to match the impact response of biological tissues. These experiments inform the design principles required for synthetic polymer gels that are optimized to predict the response of specific biological tissues to impact loading, providing insight for further tuning of this gel system to match the impact response of other "soft tissues".

Mechanism of development of aortic transection: a possible new angle

Aortic transection injury is a frequently fatal injury secondary to sudden deceleration. To date magnitude of deceleration is the only factor known to influence the development of an aortic transection injury. We hypothesise that different 3D geometries of the aortic arch in healthy young adult patients as a possible predisposing factor for transection injuries when undergoing sudden deceleration. We extend this to hypothesise that the direction of deceleration may be important as well. In addition we hypothesise that the stage in the cardiac cycle, which determines central aortic blood pressure, when the deceleration occurs as an important factor. We utilise known engineering principles such as Newton's second Law of motion, moment of inertia, law of Laplace, and the theory of superposition to explain our hypothesis. We present limited data to demonstrate the wide variation in aortic arch 3D geometry to explain the possible an individual's variable susceptibility to transection injuries via the principle of moment of inertia. Engineering principles suggest that 3D aortic arch geometry, direction of deceleration and stage in the cardiac cycle, in addition to the magnitude of deceleration are potentially important factors in predisposing certain individuals in a given situation to aortic transaction injuries.

Finite Element Aortic Injury Reconstruction of Near Side Lateral Impacts Using Real World Crash Data

Traumatic rupture of the aorta (TRA) remains the second most common cause of death associated with motor vehicle crashes, only less prevalent than brain injury. On average, nearly 8000 people die annually in the United States due to blunt injury to the aorta. It is observed that over 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest cavity. In the current study, eight near side lateral impacts, in which TRA occurred, were reconstructed using a combination of real world crash data reported in the Crash Injury Research and Engineering Network (CIREN) database, finite element (FE) models of vehicles, and the Wayne State Human Body Model - II (WSHBM). For the eight CIREN cases reconstructed, the high strain regions in the aorta closely matched with the autopsy data provided. The peak average maximum principal strains in all of the eight CIREN cases were localized in the isthmus region of the aorta, distal to the left subclavian artery, and averaged at 22 ± 6.2% while the average maximum pressure in the aorta was found to be 117 ± 14.7 kPa.

Imaging vascular trauma

Background

Over the past 50 years the management of vascular trauma has changed from mandatory surgical exploration to selective non-operative treatment, where possible. Accurate, non-invasive, diagnostic imaging techniques are the key to this strategy. The purpose of this review was to define optimal first-line imaging in patients with suspected vascular injury in different anatomical regions.

Methods

A systematic review was performed of literature relating to radiological diagnosis of vascular trauma over the past decade (2000–2010). Studies were included if the main focus was initial diagnosis of blunt or penetrating vascular injury and more than ten patients were included.

Results

Of 1511 titles identified, 58 articles were incorporated in the systematic review. Most described the use of computed tomography angiography (CTA). The application of duplex ultrasonography, magnetic resonance imaging/angiography and transoesophageal echocardiography was described, but significant drawbacks were highlighted for each. CTA displayed acceptable sensitivity and specificity for diagnosing vascular trauma in blunt and penetrating vascular injury within the neck and extremity, as well as for blunt aortic injury.

Conclusion

Based on the evidence available, CTA should be the first-line investigation for all patients with suspected vascular trauma and no indication for immediate operative intervention.

Vascular trauma in geriatric patients: a national trauma databank review

BACKGROUND

The epidemiology of vascular injuries in the geriatric patient population has not been described. The purpose of this study was to examine nationwide data on vascular injuries in the geriatric patients and to compare this with the nongeriatric adult patients with respect to the incidence, injury mechanisms, and outcomes.

METHODS

Geriatric patients aged 65 or older with at least one traumatic vascular injury were compared with an adult cohort aged 16 years to 64 years with a vascular injury using the National Trauma Databank version 7.0.

RESULTS

During the study period, 29,736 (1.6%) patients with a vascular injury were identified. Of those, geriatric patients accounted for 7.6% (2,268) and the nongeriatric adult patients accounted for 83.1% (n=24,703). Compared with the nongeriatric adult patients, the geriatric vascular patients had a significantly higher Injury Severity Score (26.6±17.0 vs. 21.3±16.7; p<0.001) and less frequently sustained penetrating injuries (16.1% vs. 54.1%; p<0.001). The most commonly injured vessels in the elderly were vessels of the chest (n=637, 40.2%), including the thoracic aorta and innominate and subclavian vessels. The overall incidence of thoracic aorta injuries was significantly higher in geriatric patients (33.0% vs. 13.9%; p<0.001) and increased linearly with progressing age. After adjusting for confounding factors, geriatric patients demonstrated a fourfold increase in mortality following vascular injuries (adjusted odds ratio, 3.9; 95% confidence interval, 3.32-4.58; p<0.001).

CONCLUSION

Vascular trauma is rare in the geriatric patient population. These injuries are predominantly blunt, with the thoracic aorta being the most commonly injured vessel. Although vascular injuries occur less frequently than in the nongeriatric cohort, in the geriatric patient, vascular injury is associated with a fourfold increase in adjusted mortality.

Delayed endovascular treatment of descending aorta stent graft collapse in a patient treated for post- traumatic aortic rupture: a case report

BACKGROUND

We report a case of delayed endovascular correction of graft collapse occurred after emergent Thoracic Endovascular Aortic Repair (TEVAR) for traumatic aortic isthmus rupture.

CASE PRESENTATION

In 7th post-operative day after emergent TEVAR for traumatic aortic isthmus rupture (Gore TAG® 28-150), a partial collapse of the endoprosthesis at the descending tract occurred, with no signs of visceral ischemia. Considering patient's clinical conditions, the graft collapse wasn't treated at that time. When general conditions allowed reintervention, the patient refused any new treatment, so he was discharged.Four months later the patient complained of severe gluteal and sural claudication, erectile disfunction and abdominal angina; endovascular correction was performed. At 18 months the graft was still patent.

DISCUSSION AND CONCLUSION

Graft collapse after TEVAR is a rare event, which should be detected and treated as soon as possible. Delayed correction of this complication can be lethal due to the risk of visceral ischemia and limbs loss.

Chest impact experiments aimed at producing aortic rupture

There are a number of proposed mechanisms of traumatic aortic rupture. These experiments involved three different chest impacts that may be associated with aortic rupture. Eleven unembalmed cadavers were repressurized and impacted by a 24-34 kg mass at 8.6-14.9 m/sec. Three impact orientations were studied with the torso axis: (1) 30-45° up from horizontal and impact 28-45° clockwise of the midsagittal axis, (2) 105-130° up from horizontal and impact 15° counterclockwise, and (3) 75° up from horizontal and impact 15° counterclockwise. Spinal acceleration was measured at T1, T8, and T12 and chest compression was determined by high-speed video. Detailed autopsy determined injuries. Impact loads averaged 9.65 ± 2.45 kN and resulted in 52.8 ± 5.4% chest compression and 3.53 ± 0.94 m/sec Viscous response. The resultant spinal acceleration was 124.5 ± 105.4 g at T1, 141.3 ± 80.5 g at T8 and 89.3 ± 39.1 g at T12. The severity of impact resulted in multiple rib fractures and severe chest injury averaging AIS = 4.2 ± 1.0. There were four cases of heart laceration and one transection of the ascending aorta 20 mm from the cusp of the aortic valve. The impacts were severe enough that aortic rupture was expected; however, only one occurred. In retrospect, the position of the heart and aorta in the upright cadaver may not have been representative of the position during human injury, thus reducing the incidence of aortic rupture in these experiments.

Endovascular therapy for thoracic aneurysm diseases: PRO

Although the long-term durability of stent grafts is still a concern, stent-graft treatment is already the best option in a large number of patients with descending thoracic aortic diseases who are poor candidates for surgical repair, or in an acute setting. With improved capability to recognize proper anatomy and select clinical candidates, the choice of endovascular stent-graft placement may offer a strategy to optimize management and improve prognosis.

Comparing ballistic wounds with experiments on body simulator

This paper demonstrates how ballistic experiments on body simulator can bring a key information in the forensic science field. In the investigated case, a hunter was shot by accident in the back. Two hunters were suspected of having inadvertently shot towards the victim. The deadly bullet left the body and cannot be found on the scene neither in the body. The only way to discriminate the two options was to perform ballistic tests in body simulators. Even though the knowledge about body simulators is not enough advanced yet to expect accurate quantitative results, it was supposed to fully discriminate the two investigated cases as its respective impact energy are highly different (respectively 1200J and 2400J). For each investigated possibility, bullet's expansion state and body wounds were simulated. Bullet impact characteristics were determined by measuring the muzzle velocity, compute the impact velocity in the considered range (the position of each hunter is accurately known). Reloading cartridges allowed to reproduce accuretaly the corresponding velocity. The body was simulated by 3 different means in order to explore the accuracy of the simulation process. We demonstrated that the reported case is situated in a velocity/energy range in which body simulators do not need to be particularly accurate to reproduce the bullet expansion/non-expansion state. It furthermore demonstrated that only one case is compatible with the ballistic wounds of the victim. In the other case, the bullet's expansion would lead to a completely different wound shape.

Occupant injury severity from lateral collisions: a literature review

PROBLEM

Side impacts are a serious automotive injury problem; they represent about 30% of all fatalities for passenger vehicle occupants. This literature review focuses on occupant injuries resulting from real lateral collisions. It emphasizes the interaction between injury patterns and crash factors, taking into account type of injuries and their severity. It highlights what is known on the subject and suggests further studies.

METHOD

We reviewed papers identified by searches in two electronic databases for the 1996-2009 publication period, and in specific journals and conference proceedings.

RESULTS

Studies on the Primary Direction of Force (PDOF) have revealed that fatal crashes occur most frequently when the PDOF is at 3 or 9 o'clock. The risk of serious injury is two to three times higher for the near-side occupant than for the far-side occupant. Head injuries predominate in oblique impacts and thoracic injuries in perpendicular ones. A few results are also reported on side airbag protection.

CONCLUSIONS

This literature review presents an overall picture of the injuries caused by lateral collisions, though each of the papers or articles examined focuses mostly on some particular aspect of the problem. The incidence of specific injuries depends on the data source used. Very few population-based analyses of lateral collision injuries were found.

IMPACT ON INDUSTRY

New studies are needed to evaluate new protective devices (e.g., lateral airbags, inflatable curtains). Without interfering with their care duties, Emergency Medical Technicians could be systematically trained to observe the collision's specific characteristics and to report all their relevant observations to the emergency physicians to increase the likelihood of prompt diagnosis and proper care.

Mechanisms of traumatic rupture of the aorta and associated peri-isthmic motion and deformation

This study investigated the mechanisms of traumatic rupture of the aorta (TRA). Eight unembalmed human cadavers were tested using various dynamic blunt loading modes. Impacts were conducted using a 32-kg impactor with a 152-mm face, and high-speed seatbelt pretensioners. High-speed biplane x-ray was used to visualize aortic motion within the mediastinum, and to measure deformation of the aorta. An axillary thoracotomy approach was used to access the peri-isthmic region to place radiopaque markers on the aorta. The cadavers were inverted for testing. Clinically relevant TRA was observed in seven of the tests. Peak average longitudinal Lagrange strain was 0.644, with the average peak for all tests being 0.208 +/- 0.216. Peak intraluminal pressure of 165 kPa was recorded. Longitudinal stretch of the aorta was found to be a principal component of injury causation. Stretch of the aorta was generated by thoracic deformation, which is required for injury to occur. The presence of atherosclerosis was demonstrated to promote injury. The isthmus of the aorta moved dorsocranially during frontal impact and submarining loading modes. The aortic isthmus moved medially and anteriorly during impact to the left side. The results of this study provide a better understanding of the mechanisms associated with TRA, and can be used for the validation of finite element models developed for the examination and prediction of TRA.