DISCUSSION
The aortic root injury is a rare but fatal complication of blunt thoracic injury if not repaired early. The valvular injury is uncommon and the aortic valve injury is the most common valvular injury, while the mitral and tricuspid valves are rarely involved (4). It may lead to type A aortic dissection and aortic valve disruption, either due to commissure detachment or rupture of the cusps leading to acute aortic regurgitation (4). Injuries to the aorta can be classified into four types: intimal tear only, large intimal flap with intramural hematoma, pseudoaneurysm and traumatic aortic rupture (TAI) (5). Blunt trauma to the chest causes injury predominantly to the parts of the heart and blood vessel that are tethered. The sites of normal anatomic tethering in aorta are aortic isthmus, which is the segment of proximal descending aorta at the confluence of mobile arch and fixed descending aorta and the aortic root, which is the confluence between the mobile heart and fixed ascending aorta (5). The differential deceleration forces that are created in these anatomic areas due to blunt chest trauma lead to shearing of tissues at the junction and make them prone to injury (5). A normal high aortic root pressure gradient across closed aortic valve during ventricular diastole further contributes to traumatic aortic leaflet injury (6).Aortic isthmus is the most common site of TAI accounting for about 80% of the cases reported (7). Prognosis is better with isthmus rupture (19.8% survival) versus ascending aortic rupture(4% survival), due to complex anatomy at the root and survival depending solely on contained hematoma at that location (8). Thoracic aortic injury has high mortality and a study has shown that 80% of victims died at the scene, underscoring the importance of urgent surgery (2). Our patient was hemodynamically stable when presented to our center as he had contained periaortic hematoma and did well after surgery.
CT angiography of the thorax and TEE are the primary diagnostic tools (9). TEE is beneficial as it helps in bedside evaluation of the extent of valve injuries, integrity of sino-tubular junction, pericardial and myocardial injuries (10). It also helps in immediate intraoperative evaluation of successful valve implantation, good coronary flow and the integrity of the repaired structures.
Open surgical repair aided by bypass-perfusion technique has been the preferred modality of repair for the ascending aortic injury. A Bentall procedure which comprises using a valve conduit to replace the ruptured aortic valve, aortic root and ascending aorta is the gold standard with good outcome (11).