In the management of thoracic aorta lesions, in contrast to that of those of the abdominal aorta, endovascular techniques were immediately considered not as a substi- tute, but rather as an adjunct to surgical techniques whose specific morbidity (spinal, pulmonary and renal) is still important.
Indeed, when stent-grafts came to be used to treat abdominal aorta aneurysms, the surgical technique was associated with a very acceptable morbidity rate, close to 5%, and to a perioperative mortality mainly related to myocardial infarction. The initial enthusiasm for this new technique was directly related to this significant re- duction of perioperative mortality owing to the minimal invasivity and to the absence of aortic clamping. Today, this is weighted by the uncertainty about midterm and long-termdurability of the aneurysmsack exclusion, and, as an effect, by the quality of the treatment, not to mention the rather unbalanced cost-efficacy ratio due to follow-up imaging studies and to the management of late complications.
The situation is quite different at the thoracic level.
Ten years have passed since the first stent-graft was de- ployed to treat an aortic lesion. The feasibility of this technique is now well demonstrated and accepted, this book having been written to state it. Regarding the tho- racic aorta, the benefit of the stent-graft became pro- gressively obvious in acute diseases (complicated type B dissection, aortic rupture, etc.) with the idea of brid- ging a gap, to stabilize, if not definitely manage a situa- tion too delicate for surgery, without hindering delayed intervention. Evidently, to deploy is not to cure, and the current concept of stent-grafts allows us in a minimally invasive way, well suited to an emergency, to quickly and safely blind an intimal tear or to restore the conti- nuity of a ruptured aortic wall. The absence of endothe- lization with current stent-grafts does not allow us, to- day, to foresee the durability of the treatment, making unavoidable a continuous follow-up. On the other hand, the late results in degenerative aneurisms and chronic type B dissections are less convincing, such as the re- sults of abdominal aorta aneurysm endovascular repair.
Thoracic aortic stent-grafts were not as frantically marketed as abdominal ones, and were initially limited
to three types: the first-generation Stanford homemade stent-grafts and two industrially made ones, Medtronic's Talent and Gore's Excluder. This allowed relatively homogeneous international registers to be built up, avoiding the potential bias due to excessively different devices. This controlled maturity allows past experience to be taken into account for clinical evaluation research to develop new concepts, such as a better fitting to arch lesions or related to stent coating.
Feasibility studies reported in the literature mainly regarded four disorders: degenerative aneurysms, type B dissections, ulcers and hematomas, and isthmus rup- ture. After 10 years the first midterm results have now been published and it seems crucial for us to insist on the need for evaluation studies based not any more on the feasibility of the stent-graft concept, but rather on the results related to each pathology, defining two main groups: acute and chronic diseases, and separating the results by pathology.
lDissection
± Type A vs type B
± Complicated vs not complicated l Aneurysms
± Degenerative
± Posttraumatic pseudoaneurysms
± Suturing false aneurysms
± Mycotic aneurysms l Aortic rupture
± Isthmus
± Descending aorta
l Hematomas and penetrating ulcers
In this decade of endovascular progress which brought about a new look at the physiopatholgy of dissection, ulcers and hematomas, we also must insist on the fan- tastic complementary advances in diagnostic imaging.
The wider availability of multislice computed tomogra- phy scanner angiography has dramatically decreased the risk of misdiagnosed posttraumatic aortic rupture, thus lowering to nearly zero the likelihood of pseudo- aneurysms in the future. Again, these acute disorders represent, in our opinion, the best application field for
Ten Years to Come
Jean-Philippe Verhoye, Jean-Franois Heautot, Alain Leguerrier
39
Chapter
endovascular procedures, with greater likelihood of ex- pected benefit. Research in imaging remains vital for future advances in endovascular techniques, with two essential techniques driven by clinical requirements: le- sion modelization and virtual angioscopy.
On a more practical point of view, real improvements have been made in delivery devices. For technical rea- sons, stent-grafts used to be relatively short, making it necessary to deploy several interconnected segments to bridge long lesions. Now, to avoid late endoleaks due to migration of segments, the trend is to use longer stent- grafts, especially for degenerative aneurysms. With the increase of coverage length, the risk of paraplegia be- comes greater, and bypassing of the supra-aortic trunks (especially the left subclavian artery) could become necessary more frequently in the future.
To sumup, this new trend in the treatment of aortic pathologies focuses the major interests of a multidisci- plinary approach, knowledge sharing and training in both surgery and diagnostic and interventional imag-
ing. This synergy is necessary for the optimal choice of surgical or interventional strategies. This cooperative management leads us to consider hybrid training, which will impose itself on the future generations of physicians.
Randomized controlled studies will probably be diffi- cult to build up owing to the low incidence of the var- ious diseases, but prospective multicentric studies, com- plying with guidelines still to be defined, are the neces- sary evaluation tools for the next 10 years.
Thanks to the cooperation of all the authors of this book, to whomwe are deeply and sincerely grateful, our wish is to promote this challenging spirit of part- nership between surgery and interventional radiology driven by the rapid evolution of treatments of aortic pathologies.
To describe which routes must be followed was the primary reason for which this work was undertaken.
Thank you for having read it.
IX. Conclusions
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