Traumatic aortic rupture, also called traumatic aortic disruption or
transection, is a condition in which the aorta, the largest artery in the body,
is torn or ruptured. The condition is frequently fatal due to the profuse
bleeding that results from the rupture. Since the aorta branches directly from
the heart to supply blood to the rest of the body, the pressure within it is very
great, and blood may be pumped out of a tear in the blood vessel very rapidly.
This can quickly result in shock and death. Thus traumatic aortic rupture is
a common killer of victims of automotive accidents and other traumas, with up to
18% of deaths that occur in automobile collisions being related to the injury.
In fact, aortic disruption due to blunt chest trauma is the second leading cause
of injury death behind traumatic brain injury.
Aortic rupture can also be caused by non-traumatic mechanisms, particularly
abdominal aortic aneurysm rupture. Causes
The injury is usually caused by high speed impacts such as those that occur
in vehicle collisions and serious falls. It may be due to different rates of
deceleration of the heart and the aorta, which is in a fixed position.
Location of rupture By far the most common site for tearing
in traumatic aortic rupture is the proximal descending aorta, near where
the left subclavian artery branches off from the aorta. The tethering of the
aorta by the ligamentum arteriosum makes the site prone to shearing forces during
sudden deceleration. An angiogram will often show an irregular outpouching
beyond the takeoff of the left subclavian artery at the aortic isthmus,
representing an aortic pseudoaneurysm caused by the trauma.
Diagnosis The condition is difficult to detect and
may go unnoticed, because many patients have no specific symptoms. Diagnosis is
further complicated by the fact that many patients with the injury
experienced multiple other serious injuries as well, so the attention of
hospital staff may be distracted from the possibility of aortic rupture.
A common symptom is unusually high blood pressure in the upper body and very low
blood pressure in lower limbs. Another symptom is renal failure where the
creatinine level shoots very high and urine output becomes negligible. In most
cases, however, the doctors would miss-interpret renal failure to issues
with the kidney itself and may recommend dialysis.
The preferred method of diagnosis is CT angiogram. Though not completely
reliable, chest X-rays are initially used to diagnose this condition when the
patient is unstable and cannot be sent to the CT bay.
The classical findings on a chest x ray will be widened mediastinum, apical cap,
and displacement of the trachea, left main bronchus, or nasogastric tube. A
normal chest x-ray does not exclude transection, but will diagnose
conditions such as pneumothorax or hydrothorax. The aorta may also be torn
at the point where it is connected to the heart. The aorta may be completely
torn away from the heart, but patients with such injuries rarely survive very
long after the injury; thus it is much more common for hospital staff to treat
patients with partially torn aortas. When the aorta is partially torn, it may
form a "pseudoaneurysm". In patients who do live long enough to be seen in a
hospital, a majority have only a partially torn blood vessel, with the
outermost adventitial layer still intact. In some of these patients, the
adventitia and nearby structures within the chest may serve to prevent severe
bleeding. After trauma, the aorta can be assessed by a CT angiogram or a direct
angiogram, in which contrast is introduced into the aorta via a
catheter. Treatment
Traumatic aortic rupture is treated with surgery. However, morbidity and
mortality rates for surgical repair of the aorta for this condition are among
the highest of any cardiovascular surgery. For example, surgery is
associated with a high rate of paraplegia, because the spinal cord is
very sensitive to ischemia, and the nerve tissue can be damaged or killed by
the interruption of the blood supply during surgery.
Since high blood pressure could exacerbate the tear in the aorta or even
separate it completely from the heart, which would almost inevitably kill the
patient, hospital staff take measures to keep the blood pressure low. Such
measures include giving pain medication, keeping the patient calm, and avoiding
procedures that could cause gagging or vomiting.
Prognosis Death occurs immediately after traumatic
rupture of the thoracic aorta 75%–90% of the time since bleeding is so severe,
and 80–85% of patients die before arriving at a hospital. Though there is
a concern that a small, stable tear in the aorta could enlarge and cause
complete rupture of the aorta and heavy bleeding, this may be less common than
previously believed as long as the patient's blood pressure does not get
too high. See also
Chest trauma Aortic dissection
Pulmonary contusion References
External links Chest Trauma: Traumatic Aortic Injury
from Trauma.org Ruptured Artery Explanation