Proximal fixation of thoracic stent-grafts as a function of oversizing and increasing aortic arch angulation in human cadaveric aortas.
OBJECTIVE
To assess the fixation of 4 commercially available thoracic stent-grafts as a function of oversizing and increasing aortic arch angulation.


METHODS
A benchtop pulsatile flow model was devised to test stent-graft anchorage in a 2-cm-long proximal landing zone at varying landing zone angles (70 degrees to 140 degrees ) and stent-graft oversizing (5% to 37%). The experiments were performed using 15 human thoracic cadaveric aortas and 4 stent-grafts with different proximal anchoring mechanisms: TAG, Zenith TX, Valiant, and Relay. The lack of device-wall apposition was measured as a function of landing zone angulation and oversizing during static and dynamic (60 pulses/min, 300/150 mmHg) tests; stent-graft collapse was also investigated.


RESULTS
The Valiant stent-graft remained apposed to the aortic wall at each increment of neck angulation and degree of oversizing. Lack of apposition of the proximal anchorage segment (Relay: bare spring; TAG: scalloped flares) was observed with the Relay above 80 degrees landing zone angulation (1-7 mm) and with the TAG above 90 degrees angulation (1-6 mm). The lack of device-wall apposition was greater with Relay than TAG (p = 0.009), but the "body" of these devices always remained well apposed. Lack of "body" apposition (1.0-7.5 mm) was first observed with the Zenith stent-graft above 70 degrees angulation (p<0.001). No stent-graft collapse was seen. An increase in stent-graft oversizing significantly (p<0.01) increased the lack of device-wall apposition for the TAG, Zenith, and Relay devices.


CONCLUSIONS
In the face of severe aortic arch angulation, stent-grafts with hooks do not improve fixation. Major factors in stent-graft design that contribute to secure proximal anchorage seem to be radial force and the presence of a proximal open stent segment.
Department of Vascular and Thoracic Surgery, Hôpital Arnaud de Villeneuve, CHU Montpellier, France. ludoviccanaud@hotmail.com
Ludovic
L
Canaud
Pierre
P
Alric
Martrille
M
Laurent
Thierry-Pascal
TP
Baum
Pascal
P
Branchereau
Charles Henri
CH
Marty-Ané
Jean-Phillipe
JP
Berthet
D000328:Adult; D001013:Aorta, Thoracic / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D001363:Awards and Prizes; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D002102:Cadaver; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011673:Pulsatile Flow; D015607:Stents