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).