The aorta is the main artery carrying oxygenated blood from the heart to the body. As it exits the heart, the vessel first moves up through the chest. This upward section is the ascending aorta. Then the artery arches and turns down, moving through the chest to the abdomen. The downward section of the artery is the descending aorta.
The descending aorta is fixed in place and cannot move. The aortic arch, however, is somewhat moveable. When a patient experiences sudden deceleration (like in a motor vehicle accident), the organs and structures inside the body continue to move. The moveable aortic arch can pull away from the fixed descending aorta. With enough force, the vessel can tear, causing blood to leak out of the aorta. This type of injury is called a blunt aortic injury (BAI).
Researchers estimate BAI occurs in less than one percent of all motor vehicle accidents. Risk is higher when the impact occurs from the front or side of the vehicle. Since the aorta is the main blood vessel feeding oxygenated blood to the body, a tear can cause severe bleeding and loss of blood to the body. In fact, 75 to 90 percent of victims die before they reach the hospital.
Without treatment, about half of those who initially survive BAI will die. Thus, emergency repair is critical. Traditionally, a repair is made through open surgery. However, open surgery in trauma victims is risky because patients tend to have numerous injuries. Researchers estimate about 10 to 20 percent of patients die during surgery, up to 10 percent develop paraplegia and 4 to 6 percent have a stroke.
Another option may be a stent graft, an expandable fabric-covered tube. Instead of making an incision into the chest, the stent graft can be inserted from the inside of the body. A small cut is made into an artery in the groin. Then a catheter is inserted into the artery. Using imaging scans for guidance, the catheter is fed through the circulatory system until the tip reaches the damaged portion of the aorta. Once the proper location is confirmed, the stent graft at the tip of the catheter is released. The stent automatically opens, pushing the fabric snugly against the wall of the damaged aorta (like a bandage from the inside). When properly positioned, the tube prevents blood from leaking out through the tear in the aortic wall.
Ali Azizzadeh, M.D., Vascular Surgeon with Memorial Hermann Heart and Vascular Institute in Houston, TX, says over time the aorta will heal. The stent graft is permanent. However, since the graft isn’t sewn in place, there is a slight risk it can move. So an annual CAT scan is recommended to verify the graft is still in the right position and no small leaks have developed.
Currently, the stent graft is only approved for patients with an aortic aneurysm (a bulging weak spot in the aortic wall that may rupture). It is being evaluated for patients with BAI and sometimes used off-label for that purpose. Azizzadeh expects the FDA to approve the device for that indication once trials are completed.
AUDIENCE INQUIRYFor general information on treatment of aortic injuries: Eastern Association for the Surgery of Trauma, http://www.east.org/tpg/chap8.pdf
BIBLIOGRAPHYCambria, R., et al., “A Multicenter Clinical Trial of Endovascular Stent Graft Repair of Acute Catastrophes of the Descending Thoracic Aorta,” Journal of Vascular Surgery, December 2009, Vol. 50, No. 6, pp. 1255-1264.
Castelli, Patrizio, M.D., et al., “Emergency Stent-graft Repair for Thoracic Aortic Injury,” Vascular Disease Management, May/June 2005, Vol. 2, No. 3, accessed from website (http://www.vasculardiseasemanagement.com), November 5, 2010.
Demetriades, D., et al., “Blunt Traumatic Thoracic Aortic Injuries,” Journal of Trauma, April 2009, Vol. 66, No. 4, pp. 967-973.
“Paradigm Shift in the Treatment of Blunt Aortic Injury,” Archives of Surgery, October 2010, Vol. 145, No. 10, pp. 1011-1012.
Propper, Brandon, M.D., and W. Darrin Clouse, M.D., “Thoracic Aortic Endografting for Trauma,” Archives of Surgery, October 2010, Vol. 145, No. 10, pp. 1006-1011.