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.