Stent-Graft Technologies 2008: AAA Conquered

Editor's Corner

Submitted on Fri, 09/05/2008 - 16:36
Authors

Frank J. Criado
Editor-in-Chief


More than half of all abdominal aortic aneurysm (AAA) repairs performed in the U.S. today are being done endovascularly. In other words, stent-graft intervention has already replaced the old open-surgery standard. Undeniably, this represents a very important and amazing development involving a therapy that is less than 20 years old from primordial inception (1990)… and less than 10 years after the initial FDA approvals (late September 1999).
AAA is an important disease process, affecting an estimated 2 million people in the United States alone. Ruptured AAA ranks high (11th) as a cause of death, but the real impact may be even higher, considering that nearly a half million sudden deaths occur each year without a definitive final diagnosis.
Modern surgical treatment evolved across several decades (since the early 1950s), with techniques and vascular grafts reaching a level of refinement and standardization by the late 1970s and 1980s. AAA repair is, arguably, a prominent “raison d’etre” for vascular surgeons everywhere.
Successful as it may be, surgical treatment, however, does imply the performance of a large intra-cavitary operation that carries significant risk potential, and a likely prolonged and often incomplete recovery. Hence, there was a clear window of opportunity for less invasive therapies that could address such unmet needs — in particular, the patients at high or prohibitive risk for surgery with a large AAA who were left with no treatment option and being sent home to await the fatal rupture…

Beginning in the 1980s, Dr. Juan Parodi and his associates (in Buenos Aires, Argentina) began to develop the concept of endovascular repair, and initiated a series of important animal experiments (Figure 1). The process culminated with the performance of the first AAA endovascular operation in late 1990.1 Their experience and lessons learned evolved rapidly (Figure 2).2 Together with parallel developments in the United States and other countries, such work spawned the explosive growth of a whole new family of vascular and endovascular technologies. The stent-graft era had arrived!
Now: fast-forward to May 2008. Four FDA-approved stent-graft AAA devices are available in the U.S. market, with a 5th endograft having been cleared just recently (on April 15, 2008) — the Talent eLPS stent-graft (Medtronic CardioVascular, Santa Rosa, California). It will be officially launched within the next few weeks. By all accounts, all these devices perform quite well, and integrity issues have been resolved. Results at 5 years and beyond are excellent, to the extent that they have now become the preferred treatment modality for the majority of patients. Anatomy has emerged as the most important factor, and the great majority of failures and bad outcomes (with all endografts) would seem to be related to off-label use. Incomplete understanding (on the part of the implanting physician) and the realities of clinical practice explain continued application of these (and other) devices outside the confines of the approved indications and instructions for use (IFU). But such off-label practices can be counterproductive and even dangerous.3 At minimum, the physician must become fully cognizant that “pushing the envelope” in this manner exposes the patient to a higher-than-normal risk, and the information must be disclosed in the process of obtaining informed consent.
What’s next for AAA endovascular technologies? The expansion of anatomical indications to include very short or no-neck AAAs through the use of fenestrated or branched endografts will no doubt be part of the future. And non stent-graft endovascular solutions are likely to emerge as well. Lastly, let’s not forget or abandon our surgical skills… for open surgery will surely continue to be necessary in a number of clinical situations for many years to come.