Classification of blunt aortic injuries a new systematic overview of aortic trauma

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.

Quantitative study of aortic strain injuries originating from traffic accidents

Aortic injuries are the second leading cause of death after head injuries due to traffic accidents, and strain-induced injuries are becoming increasingly prominent. The quantitative study of aortic strain injury allows for a rapid assessment of the degree of aortic injury after an accident and timely diagnosis of the pathology of aortic injury. It is more reliable than diagnosis based on clinical symptoms alone and it is faster than diagnosis based on imaging. Based on the porcine aortic tensile and injury tests, this study obtained the maximum stress threshold of the aorta that can withstand tensile stress and the safe stress threshold under tensile action, which provides a more detailed data reference about aortic injury in the field of internal medicine. Injuries to the aorta under various degrees of traction were analyzed in detail. A comprehensive and quantitative evaluation criterion for aortic strain injury was proposed, which provides a more in-depth reference for the mechanism of aortic strain injury. In addition, combining it with current imaging promises a combination of numbers and shapes for rapid and accurate diagnosis of aortic strain injury.

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.

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.

Traumatic fatal aortic rupture in motorcycle drivers

Traumatic fatal aortic rupture (FAR) is a common finding in victims of motor vehicle crashes (MVC), but its aetiology and mechanisms of production remain an issue of major concern, above all in motorcyclists. This study reports a series of cases obtained from a retrospective analysis of traumatic FARs occurring in motorcycle drivers, with the aim of defining the injury patterns and correlating them with the mechanisms of FAR production. Circumstantial, autopsy and histology data were collected through a retrospective analysis of post mortem examinations performed at the Institute of Legal Medicine of the University of Padova between 2014 and 2016. Among 151 traffic related victims, 8 were motorcycle drivers and displayed traumatic FAR and were thus included in the study. In 7 cases, the presence of abdominal/thoracic injuries suggested that the external compression due to the accident was at least a concurrent cause of FAR, being the predominant mechanism of aortic injury in 4 cases, through the "osseous pinch" or the "waterhammer effect" mechanisms. Our study highlights the well-known role of "preventative forensic pathology", which has become routinary in traffic medicine since many years, also for defining the points of impact and the injury patterns of motorcyclists sustaining traumatic FAR, thereby facilitating the development of new prevention strategies and devices. Further studies, however, are needed in order to widen the investigated population and to estimate the real number of victims for which traumatic FAR might hypothetically be prevented with specific countermeasures.

Toward Reduction of Post-Hospital Admission Death Rate Caused by Acute Traumatic Aortic Tear

BACKGROUND

Terminology and classifications are the vehicles by which pathologic conditions are identified and understood. It is critically important for the patient admitted with suspected blunt thoracic aortic injury that admitting physicians have a thorough knowledge of acute traumatic aortic tear and its natural history.

OBJECTIVES

The objectives of this review were as follows: (1) to introduce a pathology-based terminology and classification of acute traumatic aortic injuries that unambiguously defines each, and (2) to emphasize the clinical relevance of acute traumatic tear to post-hospital admission deaths in blunt thoracoabdominally injured patients.

METHODS

This is a literature review of 32 refereed articles pertaining to acute traumatic thoracic aortic injury published from 1957 to the present.

RESULTS

The terminology used to describe aortic injury is inconsistent. Several terms are often loosely interchanged: tear, laceration, transection, and rupture. Furthermore, classifications of aortic injuries have been proposed based on microscopic or gross pathologic or computed tomography scan results. While microscopically-based classifications have little or no clinical application, a classification based on gross pathology provides information useful for aortic injury prognosis and management.

CONCLUSION

Reduction of post-hospital death caused by acute aortic tear requires knowledge and understanding of the pathology of acute traumatic aortic tear and its natural history. Such understanding of pathology of acute traumatic aortic tear and its natural history is enhanced by terminology that defines the aortic injury. Therefore, we present our proposed terminology and classification of acute traumatic injuries.

Blunt aortic injury: risk factors and impact of surgical approaches

PURPOSE

This study reviews our 17-year experience of managing blunt traumatic aortic injury (BTAI).

METHODS

We analyzed information collected retrospectively from a tertiary trauma center.

RESULTS

Between October 1995 and June 2012, 88 patients (74 male and 14 female) with a mean age of 39.9 ± 17.9 years (range 15-79 years) with proven BTAI were enrolled in this study. Their GCS, ISS, and RTS scores were 12.9 ± 3.7, 29.2 ± 9.8, and 6.9 ± 1.4, respectively. Twenty-one (23.8 %) patients were managed non-operatively, 49 (55.7 %) with open surgical repair, and 18 (20.5 %) with endovascular repair. The in-hospital mortality rate was 17.1 % (15/81) and there were no deaths in the endovascular repair group. The mean follow-up period was 39.9 ± 44.2 months. The survivors of blunt aortic injury had lower ISS, RTS, TRISS, and serum creatinine level and lower rate of massive blood transfusion, shock, and intubation than the patients who died, despite higher rates of endovascular repair, hemoglobin, and GCS on presentation. The degree of aortic injury, different therapeutic options, GCS, shock presentation, and intubation on arrival all had significant impacts on outcome.

CONCLUSIONS

Shock, aortic injury severity, coexisting trauma severity, and different surgical approaches impact survival. Endovascular repair achieves a superior mid-term result and is a reasonable option for treating BTAI.

Suicide of a cyclist

The rate of suicides in road traffic fatalities is estimated at 1-8% depending on the investigated study material. Especially single-car accidents, for which no technical reason or driving error is apparent, are considered suspicious. The elucidation of suicides in road traffic is difficult if there are no relevant clues such as the announcement of suicide plans shortly before the event or a suicide note. Individuals who intentionally kill themselves in road traffic often have a history of mental illness. The authors report on a suicide using a bicycle. A 71-year-old man intentionally drove into the wall of a house situated at the end of a hill road and suffered an open craniocerebral trauma and an aortic rupture. The pattern of findings and the circumstances of the case are described.

Thoracic aortic dissection in a 38-year-old man

A few days before Christmas, a flight team was activated for an interfacility transfer of a 38-year-old man with a history of hypertension and spinal stenosis diagnosed with a thoracic aortic dissection. The patient was presented to a local community hospital complaining of nearly 5 days of left-sided rib pain. This afternoon when he stood up from a chair, he experienced a near-syncopal episode. Concurrently, he had an abrupt onset of a tearing sensation in his chest that radiated to thoracic spine in the region between his shoulder blades. Ground emergency medical services (EMS) was called, and the patient was transported to the community hospital. During the initial transport and evaluation by the emergency department (ED) staff, the patient was noted to be hypertensive, with a systolic blood pressure greater than 180 mmHg. In the ED, the patient received aspirin, morphine, and Lopressor. He underwent a chest x-ray (Figure 1) and computed tomography (CT) scan and was diagnosed with a type B thoracic aorta dissection, which was noted to start on the descending thoracic aorta distal to the left subclavian artery and extend to the level of the celiac trunk (Figure 2). Despite the initial beta blockade, the patient was noted to be profoundly hypertensive, with initial blood pressure greater than 190 mmHg systolic. The flight team was activated for hemodynamic management and rapid transport to a facility capable of vascular and cardiothoracic surgery.