TEVAR More Complex, Dangerous Than Endo AAA Repair

By Kerri Wachter

NEW YORK -- Thoracic endograft stenting is more complex and more dangerous than endograft repair of abdominal aortic aneurysm, said Dr. Frank J. Criado, who is chief of the division of vascular surgery at Union Memorial Hospital in Baltimore.

Dr. Criado offered his top five reasons why thoracic endovascular aortic repair (TEVAR) is tougher and riskier than repair of abdominal aortic aneurysm (AAA) at the Veith symposium on vascular medicine sponsored by the Cleveland Clinic.

• Death. Death is "a distinct, albeit unlikely, possibility in TEVAR, but [is] essentially unheard of in the case of endovascular aortic repair for abdominal aortic aneurysm," he said. Possible causes of intraoperative death include aortic perforation and rupture; retrograde type A dissection; access-related hemorrhage; and unintentional coverage of all aortic branches. These situations typically occur in procedures in or near the arch; when there is complex anatomy involved; or in cases of acute dissection.
• Access. Access issues "continue to be important problems for all of us actively involved in TEVAR procedures," said Dr. Criado, who is also the director of the center for vascular intervention at Union Memorial Hospital. Many of these patients have associated severe calcific atherosclerotic disease access issues. "All too often, we continue to have to procedures such as the iliac access conduit. ... [It] is a heck of a lot better to do that preemptively, when you think you might not be able to get through those arteries with a large sheath." Access problems are more common in TEVAR than in EVAR because of the large size of currently available thoracic endograft devices, which require delivery systems ranging from 22F to 27F in profile. In addition, women--with smaller access arteries--make up 30% of TEVAR patients as opposed to fewer than 20% of EVAR patients.
• Arch issues. "The aortic arch is truly the Achilles' heel of TEVAR intervention," said Dr. Criado. The curved anatomy of the arch--the knuckle--is a particularly troublesome location. "There is no currently available device that really conforms well when you deploy at that point." It's important to keep this in mind and to deploy the device either well below or above this site, he said.
• Anatomy assessment and planning. "Anatomy assessment and careful planning of the procedure--before the procedure--are clearly the most important steps in every TEVAR intervention," said Dr. Criado. CT angiography and 3-D reconstructions are the main tools used for assessment and planning. Despite careful planning, errors and miscalculations occur. "It takes quite a bit of seasoned-experience skills and previous experience with these procedures to fully understand just what you are up against in planning these TEVAR interventions, especially when they involve management of the aortic arch," said Dr. Criado.
• TEVAR technology. The devices currently available for TEVAR were created for AAA treatment, not for the thoracic aorta or the aortic arch. "Essentially [TEVAR endografts] are about 5 years behind their abdominal counterparts," said Dr. Criado. He disclosed that he is a consultant and advisor to Cordis Endovascular.

Asked to comment on this article, Dr. James McKinsey, chief of vascular surgery at Columbia University Medical Center in New York, said: "Additional reinforcing statements would include that the anatomy of the thoracic aorta is significantly more complex than the abdominal aorta, requiring precise delivery of larger devices in more tortuous areas of the aorta (aortic arch) and that there is more stored energy in the devices going through tortuous vessels at the time of delivery compared to an AAA.

"As stated, the take-off of the cerebral vessels is intimately related to the proximal landing of the TEVAR graft and increases the potential of coverage or embolization into these vessels. Finally one must also compare the potential alternative to TEVAR being open repair and certainly the multiple risks of open repair of the thoracic aorta are markedly greater than TEVAR or open AAA repair," he added.

"Any decision regarding treatment options has to be weighted against the other treatment options for that specific pathology. The advances and improvement in outcomes that we have seen comparing early versus more recent endo AAA repair should certainly be expected as newer TEVAR grafts become available and as experience increases," Dr. McKinsey concluded.