DISCUSSION
Aortic arch replacement remains a challenging operation. When the
descending thoracic aorta is involved, treatment should be extended
distally, increasing operation complexity and surgical risk. Distal
completion can be obtained after a classic ETR, thanks to the prosthetic
segment left in the descending aorta, or through a frozen ETR procedure,
that encompasses conteporary arch replacement and endoluminal exclusion
of distal aortic disease.
The first is an established operation, providing excellent results.(4)
Nonetheless, the distal anastomosis with the invaginated prosthesis is
demanding, especially in AAD. Moreover, it implicates the use of a
straight vascular prosthesis and the reimplantation of an aortic cuff
including the origins of the supra-aortic vessels: a long anastomosis
that can be very difficult to re-explore once completed.
On the other hand, frozen ETR requires the availability of dedicated
material and whole-team adequate expertise, the latter being not easy to
acquire, due to the rarity of the disease.
We therefore conceived two possible alternatives to the classic
procedure that are easier to perform, while maintaining the possibility
of a safe secondary correction of residual disease in the descending
aorta.
The first operation is a true “modified ETR”. A similar, although much
more complex, modification has already been proposed in the past.(5) In
our technique, the ET is independently anastomosed inside the distal
lumen. Therefore, the suture is easier to perform, due to increased
visibility and simpler graft handling. The time needed for the
additional suture line between the arch prosthesis and the distal aortic
stump equipped with the “trunk” should be compensated by these
technical advantages. Also the three supra-aortic sutures will be
completed more quickly than the cuff anastomosis, and a shorter HCA time
will be obtained if an additional “service branch” for distal
perfusion is available.
Another advantage is that the distal skirt diameter can be freely chosen
to accommodate for potential dimensional discrepancies.
The second operation might be rather considered a “prophylactic arch
debranching”. The technique is just based on leaving a distal tail in
the prosthesis, after the origin of the side branch for left subclavian
artery. The branch-free tail will actually substitute the transverse
arch. The origins of the supra-aortic vessels will be therefore
displaced proximally, and they will assume the position that they would
have taken after a typical surgical arch debranching. This avoids the
need for a second open procedure by preparing a zone 1 landing during
the first procedure.
“Modified ETR” should be more useful in case of chronic expansive
disease, where the positioning of the free-flowing prosthetic segment is
easier to accomplish. “Prophylactic debranching” should be more
convenient in AAD, since it requires a single distal suture line and
forestalls the insertion of any prosthetic segment in a fragile, and
scarcely visible, distal lumen.
Both techniques appear to be reproducible and easy to perform, avoid
difficult maneuvers included in the original ETR, do not require any
particular expertise or specific training, do not need the use of
dedicated material.