Discussion
One of the most fearsome complication that can occur during percutaneous
coronary intervention is an iatrogenic acute aortic dissection that
could extend retrogradely into the ascending aorta. A diseased vessel
wall with multiple calcification and atherosclerotic plaques seems to be
the most important predisposing factor. In most cases coronary
dissection is easily diagnosed during the coronary angiography, which
usually reveals a true and a false lumen, separated by a radiolucent
intimal flap and a dye staining persistently localized. [3]
The process underlying IAAD is not yet completely clear; in fact there
are different mechanisms involved. Firstly, the dissection may be caused
by the high-pressure injection of contrast medium on a pre-existing
dissection breach. Secondly shearing forces during systole and diastole
could explain the propagation of the dissection in a retrograde sense.
Finally, the entry breach could also be created by direct trauma of the
angiographic catheters and increased by forced injection of contrast
medium. [4]
The type of treatment is different depending on the type and extension
of the dissection. For IAAD that remains localized at the level of the
Valsalva sinus during the procedure and that extend in a retrograde form
it is preferable to maintain a conservative attitude, as most tend to
spontaneously regress with the collaboration of the antegrade aortic
blood flow. [5]
If the dissection extends less than 40 mm from the coronary ostia into
the ascending aorta and progresses in an antegrade fashion then it is
preferable to intervene by stenting the affected coronary artery so as
to close the breach and prevent the dissection from spreading. [6]
The third type of strategy consists in an emergency ascending aorta
replacement and is recommended if the dissection extends more than 40 mm
from the coronary artery ostium, if the patient is hemodynamically
unstable, presents with severe aortic insufficiency, has hemopericardium
or if the guidewire fails to cross the occluded lesion. Coronary
stenting can be useful in these cases as a ”bridge to the
surgery ” and can avoid or reduce the progression of the dissection.
In conclusion, the goal in the treatment of IAAD should be closing the
intimal tear as quickly as possible in order to prevent the progression
of dissection and to avoid damage to neurological system and other
end-organs. A percutaneous attempt is always recommended if suitable,
but if it does not achieve a satisfactory result a prompt ascending
aortic replacement is mandatory.