Traumatic aortic rupture refers to a condition in which there is a tear or rupture of the aorta. It is caused by motor vehicle accidents or severe falls and the majority of affected individuals dies at the scene.
Patients who are admitted with TAR generally show symptoms of severe hemorrhage and cardiovascular failure. Symptom onset is often peracute and patients who reach the hospital relatively stable may suddenly decompensate if, for instance, tissue opposing an aortic hemorrhage breaks. Upon admission, these people may not show any symptoms at all or they may claim retrosternal chest pain, dyspnea, and cough resulting from a space-occupying intrathoracic hematoma. Systolic heart murmurs are often heard; blood pressure may differ between upper and lower limbs. Instable TAR patients usually have a systolic blood pressure of < 90 mm Hg, a barely palpable pulse, tachycardia and tachypnea. Their skin may be cool and damp, their mucosal membranes pale or cyanotic. Depending on the overall blood loss, they may loose conscience.
Due to the etiology of TAR, the vast majority of patients will present additional injuries. Fractures, further thoracic and abdominal injuries have been reported in 70, 50 and 40% of patients admitted with TAR . Such lesions may significantly contribute to the poor overall condition of the patient. In the case of contained aortic hemorrhages, other injuries may even take priority over the TAR, e.g. neurosurgical and laparotomic interventions .
None of the above-mentioned symptoms and signs are characteristic for TAR; on the contrary, similar alterations may be presented by patients suffering from hypovolemic shock due to any other reasons. But any delay in adequate treatment may worsen the outcome and there may be no time for extensive diagnostic measures. The following may be considered:
There are basically two treatment options: aortic repair during open surgery or endovascular stent placement. The latter has gained popularity in recent years and retrospective studies show endovascular treatment to be as effective but less invasive than open thoracic surgery  . Endovascular aortic repair is not restricted to delayed surgery but can also be conducted as an emergency measure. This way, additional blood loss can be avoided, and systemic anticoagulation does not become necessary and thus does not interfere with other hemorrhages. It is also the faster alternative.
Furthermore, standard therapeutic measures have to be taken to compensate for aortic hemorrhages and to treat comorbidities. With regards to the former, fluid resuscitation, most likely transfusion of blood products, and thoracic drainage with chest tubes is generally indicated. If TAR has not been diagnosed before a chest tube is used, recovery of more than half a liter of blood is highly suggestive of aortic injury. In order to prevent further blood loss, beta blockers may be applied. Hemorrhages may also exacerbate if the patient is coughing or gagging, and these reflexes should be attenuated, for example by the use of intravenous lidocaine before endotracheal intubation.
As has been delineated above, TAR is fatal in the vast majority of cases. Due to rapid exsanguination, health caregivers are generally unable to reach the site of the accident before the victim dies. A minor share of patients reaches the hospital alive, but even among these individuals, mortality remains high. According to a recently published retrospective study, 50% of TAR patients suffered cardiopulmonary arrest shortly after arriving at the hospital; another 8% died after emergency operations . Early surgical intervention is often the only chance for an affected person to survive TAR.
The outcome is somewhat better if aortic hemorrhages are contained in restricted anatomical spaces. The dense periaortic tissue, for instance, may serve as a life-saving barrier . TAR may also refer to the mere dissection of aortic intima and media. In these cases, the aortic adventitia in conjunction with periaortic tissue may impede immediate exsanguination, which prolongs the time window for surgery and increases the chance of survival. The statement given above does not, however, apply to bleedings into the pericardial space. These most likely lead to cardiac tamponade, cardiogenic shock, and death.
Prognosis may be even worse in the case of life-threatening comorbidities, which are often observed in patients who sustained severe thoracic trauma.
Blunt trauma, usually sustained in motor vehicle accidents or severe falls, is the main cause of TAR. The aortic wall is unable to withstand strong mechanical forces, namely those acting upon sudden deceleration. The risk of fatal TAR correlates with the magnitude of those forces and is thus increased if the patient impacts without being restrained by a seatbelt or similar safety installations.
Less frequently, penetrating lesions - either resulting from accidents or violent actions - account for transecting aortic injury .
Pre-existing aortic lesions, e.g., thoracic aortic aneurysm or abdominal aortic aneurysm, render patients more susceptible to TAR.
In the majority of cases, TAR results from motor vehicle accidents. Most TAR patients are males, preferentially young adults in their third decade of life. This presumably results from an increased prevalence of risk behavior in that patient group.
Interestingly, overweight and obese people have been reported to be frequent victims in TAR patient cohorts.
The left cardiac ventricle pumps blood into the aorta, from where it is distributed throughout the whole body. The aorta emerges from the left heart, ascends, gives rise to coronary arteries, and follows an arch in the posterior and left direction. The brachiocephalic artery, left common carotid artery and left subclavian artery emerge from this arch. The aortic arch narrows down, turns into the aortic isthmus, and re-expands as descending aorta, which passes the diaphragm through the aortic hiatus. At this point, the thoracic aorta turns into the abdominal aorta. The bifurcation into the left and right common iliac arteries constitutes the end of the aorta.
More than 50% of TAR victims suffer aortic isthmus rupture, i.e., vessel transection occurs in close proximity to the heart in the thoracic cavity . The aortic isthmus is tightly connected to the left pulmonary artery. The ligamentum arteriosum, a remnant of the ductus arteriosus, consists of taut connective tissue and reduces the mobility of this part of the aorta. In the case of blunt trauma, other sections of the aorta may resist shearing forces to a limited extent by shifting. The aortic isthmus can't and ruptures rather easily. The second most frequently affected part of the aorta is even closer to its origin and comprises ascending aorta and aortic arch.
The amount of blood passing the aorta corresponds to the cardiac output which in the condition of rest amounts to approximately five liters per minute. Consequently, complete TAR leads to rapid exsanguination and death. According to the number given above, and provided that death occurs after losing two or three liters of blood, a patient whose aorta ruptures proximal to the heart would die within half a minute. However, blood flow in the case of the rupture of the most distal part of the abdominal aorta is still high and survival times after complete rupture of this aortic part are somewhat longer than after proximal TAR.
All possible efforts should be made to avoid this life-threatening injury. Since most TAR are sustained during motor vehicle accidents, the corresponding safety measures should be adhered to. As has been indicated above, failure to fasten the seatbelt significantly increases the risk of TAR in the case of an accident. Speed limits should be respected as well as the prohibition of dangerous overtaking. Similarly, appropriate security measures should be taken into account while realizing other, potentially dangerous activities.
Large parts of the aorta are only loosely attached to adjacent tissues, with the exception of the aortic isthmus. This short section of the vessel is connected to the pulmonary artery and thus behaves differently than more proximal or more distal parts if exposed to severe mechanical forces. Consequently, most TAR affects the aortic isthmus.
Complete TAR generally causes rapid exsanguination and death; most affected individuals die at the scene within a few minutes. In some cases, aortic hemorrhages may be contained by periaortic tissues. Here, exsanguination may be delayed and health caregivers may have a chance to intervene and repair the artery before the patient decompensates. Emergency surgery - either performed as open thoracic surgery or endovascular vessel repair - have to be carried out.
Traumatic aortic rupture (TAR) refers to transection of the aorta, main artery of the human body. It is generally caused by motor vehicle accidents or severe falls and the majority of affected individuals dies at the scene. High mortality rates result from rapid exsanguination. About five liters of blood are pumped through the aorta every minute and blood losses exceeding two or three liters are generally fatal. Thus, health caregivers rarely have a chance to attend TAR patients before they fall victim to the causative accident.
Consequently, all possible measures should be taken to avoid TAR and because blunt trauma sustained in motor vehicle accidents account for the vast majority of cases, this basically refers to driving in a responsible way. Speed limits should be respected as well as a prohibition of dangerous overtaking and other traffic rules. Nobody should ride a car after drinking alcohol or consuming drugs. This way, the necessity for emergency surgery to repair a ruptured aorta is largely reduced.