Methods Compared for Guiding Type B Aortic Dissection Stents

Hank Russell

NEW YORK -- Both intravascular ultrasonography and transesophageal echocardiography were superior to angiography in identifying multiple entries, in diagnosing false lumen slow-flow after stent-graft implantation during the treatment of type B aortic dissections. Both were also superior in detecting incomplete stent apposition, according to a study presented at the Veith symposium on vascular medicine sponsored by Montefiore Medical Center.

The study comparing angiography, TEE, and IVUS intraprocedurally before and after placement of 48 stent grafts in 42 consecutive patients (12 female, average age 61 plus or minus 11 years) with acute and chronic type B aortic dissection for both usefulness and capability to guide aortic stent-graft implantation was presented at the symposium by Dr. Dietmar H. Koschyk of the University Hospital Hamburg-Eppendorf in Germany.

"The main thing was that the number of aortic stent-graft implantations has grown dramatically over the last few years, but there are still overall guidelines on how to implant stent grafts and how to do the procedure," Dr. Koschyk said.

Although TEE only has access to the thoracic aorta, it has the ability to visualize both the true and false lumen, guidewire position, slow-flow on the false lumen, and to detect the presence of an endoleak. Its color Doppler echocardiography capability enables seeing endoleaks that are hard to see in angiography, according to Dr. Koschyk. The disadvantage of TEE is that it does not have access to the abdominal aorta and the apex of the thoracic aortic arch.

In IVUS, the imaging is from inside the aorta and provides 360-degree scanning capability. "You can easily separate the true lumen and the false lumen," Dr. Koschyk said.

In contrast with angiography alone, guidewire position over the entire length of the aorta was documented more frequently by TEE and IVUS. In four patients with abdominal extension of the dissection, only IVUS was able to accurately identify the false lumen over the entire length of the diseased aorta. TEE was superior to IVUS and angiography in the detection of endoleaks. Intraprocedural angiography, TEE, and IVUS had been performed without complications in all patients.

Dr. Koschyk concluded that TEE in conjunction with angiography appears to be advantageous and adds incremental information to safely guide stent-graft placement in type B aortic dissection. Additional use of IVUS was found to be helpful in patients with complex anatomy and abdominal extension of the dissection.

"In conclusion, our opinion is to have as much information as possible prior to the implantation to make for precise planning of not only patient selection, but of the procedure itself. You have to guide the implantation, so we use angiography every time," he said. "The more information you have, the better you can do the implantation."