“I believe the three most important device-related features to prevent migration are: (1) active proximal fixation in the form of barbs to help the graft resist the physiologic force of the aortic blood flow; (2) a long main body with a low bifurcation to improve the columnar strength of the graft, once again to deal with the hemodynamic force of the blood flow in the aorta; and (3) flexibility within the graft to conform to tortuous anatomy and maintain a seal.”
DR. MATTHEW LONGO
University of Nebraska Medical Center
Omaha VA
Omaha, NE

“For me, there are three key things that influence my decision on which endograft to choose and implant. The first is the accuracy and precision of device deployment. If a device is deployed and lands where it is intended to, then the chances of migration or an endoleak are much lower. Moreover, less additional devices are then needed to prevent a future leak or device migration. The second important property of a device is its method of active fixation. In my experience, grafts that have barbs or hooks tend to migrate less, which further reduces the number of endoleaks. Finally, a device's radial force is crucial. Grafts that have strong radial forces associated with them tend to fall or migrate less. In addition, they require less additional stents. In general, the fewer additional devices or maneuvers that are required to treat a patient, the better both the short and long-term results will be.”
DR. MICHAEL WILDERMAN
Hackensack University Medical Center
Hackensack, NJ

“Active fixation, appropriate neck apposition and seal, and extensive size options to accommodate aorta and iliac anatomy.”
DR. LUIS SANCHEZ
Washington University, Barnes-Jewish Hospital
St. Louis, MO

“One, that the graft can be deployed accurately and predictably. This is especially true in cases of a short and/or suboptimal neck. Maximizing the seal zone is of critical importance in these cases; (2) active fixation of any kind will increase the displacement force necessary to dislodge the graft; and (3) the ability to handle neck angulations and conform to the neck. This will maximize apposition of the graft.”
DR. EVAN LIPSITZ
Montefiore Medical Center
Albert Einstein College of Medicine
Bronx, NY

“I believe the most important factors contributing to migration and endoleaks is first and foremost patient selection. In some cases, even though the proximal neck may meet the upper limit of the size recommended by the IFU, the pararenal aorta is not healthy and will continue to grow, leading to future migration and failure. Columnar strength is another factor, hence the importance of covering the aorta from the renal arteries to the hypogastric arteries. Proximal stent radial force and active fixation are device attributes creating a seal and reducing the risk of migration.”
DR. ALI SHAHRIARI
Methodist Hospital
Indiana Heart Hospital
Indianapolis, IN

“From a seal standpoint, I think the three major attributes are conformability to the neck, good radial strength to the graft at the seal zones, and the use of a long graft body to maximize apposition and even cover more lumbars. From a fixation standpoint, I think using the aortic bifurcation for anatomic support is the most physiologic option and has other added benefits. Positive fixation and suprarenal fixation are also worthwhile in appropriate anatomies.”
DR. MATT JUNG
Baptist East Hospital
Louisville, KY

“At first, we thought the most critical factors were appropriate graft sizing and radial force from the stent graft. However, from our experience over the years, we now know that those are not the only factors to prevent graft migration and type I endoleaks. Active proximal fixation is absolutely crucial to ensure the graft remains in place. Finally, columnar strength prevents proximal and distal graft retraction that could result in migration and subsequent endoleak. Combining active fixation, radial force, and columnar strength provides us the best combination for success.”
DR. NABEEL RANA AND DR. SYED HUSSAIN
Heartcare Midwest
Peoria, IL

“Barbed top stent, radial strength of top stent, and controlled accurate deployment.”
DR. CHERRIE ABRAHAM
Jewish General Hospital
McGill University
Montreal, Quebec, Canada

“Active fixation (eg, barbs), suprarenal fixation, and stent graft to aortic wall apposition.”
DR. GUSTAVO ODERICH
Mayo Clinic
Rochester, MN

“Barbs, radial force, and correct oversizing.”
DR. MARCELO FERREIRA
SITE Group
Rio de Janeiro, Brazil

“In answering this question, it is critical to distinguish these two events (ie, migration and endoleaks) as separate but related failure modes of an endograft. Graft designs that don't consider these separately, in my opinion, have more limited applicability than those that consider them as separate design factors.
As such, active fixation is a significant factor in limiting migration. Active fixation is provided by hooks or barbs that embed in the wall of the aorta preventing graft movement. All grafts have an element of active fixation provided by the radial force of the proximal stent, but this is limited to the degree and length of apposition to the aortic wall. The shorter and/or more abnormal (thrombus, calcification, angulation) the neck, the more tenuous the fixation provided by friction alone and thus the benefit of active fixation with hooks/barbs. By design, active fixation should maintain graft position even as the patient's posture and therefore aortic axial shape changes with time.
Passive fixation is defined by physical factors such as the columnar strength of the graft often augmented by extending limbs to the iliac bifurcations. Another manner in which passive fixation prevents movement is by a uni-body, bifurcated design that seats the graft bifurcation on the aortic bifurcation, thereby eliminating any possibility of movement.
Preventing endoleak requires sealing of the graft to the arterial wall at the proximal and distal attachment sites. The exact length of apposition needed to provide complete seal is ill defined. However, the condition of the seal zone will certainly influence this event. Thrombus and calcification will both impact the ability of the graft to juxtapose to the arterial wall and therefore increase the length needed to achieve seal. Graft material designs that stimulate an inflammatory response to promote some level of graft incorporation will also encourage seal. Dacron is far more proinflammatory than polytetrafluoroethylene and may therefore provide an advantage in achieving seal and preventing endoleaks.”
DR. SCOTT S. BERMAN
Tucson Vascular Specialists
Tucson, AZ

“Proper graft-to-aorta match, proximal fixation capabilities, and graft conformity to the aorta post-balloon angioplasty.”
DR. EDWIN DUNCAN
East Texas Medical Center
Tyler, TX

“Patient selection, active fixation, and appropriate oversizing.”
DR. BENJAMIN W. STARNES
University of Washington
Seattle, WA

“First, anatomic patient selection is key. The anatomy must be suitable for endovascular grafting, including a diameter that permits adequate oversizing, a proximal neck that does not have significant laminated mural thrombus, and absence of a reverse-taper configuration. Second, active suprarenal fixation dramatically reduces the chance of graft migration. Finally, well-controlled deployment mechanisms (such as that associated with the Zenith delivery catheter) permit highly accurate placement of the main body device at the intended location, which allows the surgeon to maximize fixation/contact in the proximal neck of the aorta.”
DR. STEVEN MERRELL
Intermountain Medical Center
Salt Lake City, UT