Multilayer flow modulator stents (MFMs) could be incredibly valuable for the resolution of complex thoracoabdominal aortic aneurysms. MFMs are not only effective, they also appear to carry no risk for loss of native side branches.
Sherif Sultan, MD, FACS(Hon), from the Western Vascular Institute in Galway, Ireland, presented the results of a study of 55 cases of MFMs at the American College of Surgeons 98th Annual Clinical Congress.
Lois A. Killewich, MD, PhD, FACS, from the University of Texas Medical Branch in Galveston, who moderated the session during which the results were presented, told Medscape Medical News that "this is very exciting new technology."
Dr. Sultan described how MFMs allow for physiologic modulation of the aneurysm and reported that they reduced sac volume in 65% of the cases. Although the patients have been followed for up to 18 months, long-term follow-up is necessary.
Dr. Sultan began by describing his experience with currently available branched devices, which "take about twelve hours and the patient is always sick afterwards."
He then described the MFM: The device is a fluid-smart multilayer stent that is made of self-expandable mesh. The MFM channels flow to the side branch. The flow vortices are slowed, but the side branches remain patent. The MFM is available off the shelf and requires minimal training.
"You put in the stent and there is an expansion of the aneurysm.... This suddenly decreases the pressure on the aortic wall.... The whole idea is to realign the flow," Dr. Sultan explained. A main concern in these situations is endotension (i.e., high pressure on a closed sac).
"Untreated endotension can lead to aneurysm rupture, which causes massive bleeding and is usually fatal," Dr. Killewich noted. The MFM decreases endotension because all of the pressure that comes into the sac is able to leave the sac.
The MFM must be placed from normal aorta to normal aorta; it cannot be used if there are branch-related problems (e.g., narrowing).
The 55 patients reviewed by Dr. Sultan and colleagues came from the Global Independent MFM Registry of 243 cases implanted worldwide. The primary end point of their study was freedom from rupture and aneurysm-related death.
Mean age was 64.5 years. The three deaths that occurred in the study population were attributed to human error; none were related to MFM failure.
The Future of Thoracoabdominal Aortic Repair
Dr. Sultan reported a 98.2% technical success rate and a 93.7% aneurysm-related survival rate. He added that several patients experienced complete resolution of the thoracoabdominal aneurysm.
At six months, the sac volume had increased by 0.3% per month. Peak expansion was at five to six months; after that, the aneurysm started to collapse.
Advantages of the MFM include rapid patient turnover and decreased complication rate. "This may be the future of endovascular thoracoabdominal aortic repair," Dr. Sultan stated.
In an email to Medscape Medical News, Dr. Killewich explained that "this is the area where endografts have not previously been adopted because of the poor outcomes with branched and fenestrated grafts."
Research and development is currently underway for the second-generation of MFM, according to Dr. Sultan.
He is enthusiastic about the potential of MFMs to save lives, and explained that, to date, "all of these patients are compassionate cases." He added: "I have no connection with this company."
The current limitations are primarily in the areas of compatibility with imaging modalities and interlayer interstent metallic shear stress material fatigue, he noted.
The audience response to the presentation was very enthusiastic. "Fantastic. I hope it works," declared one audience member upon leaving the lecture.
Dr. Sultan and Dr. Killewich have disclosed no relevant financial relationships.
American College of Surgeons (ACS) 98th Annual Clinical Congress: Abstract NP2012-24335. Presented October 3, 2012.
Lara C. Pullen, PhD • Medscape Medical News © 2012 WebMD, LLC