An In Vitro Phantom Study on the Role of the Bird-Beak Configuration in Endograft Infolding in the Aortic Arch.
OBJECTIVE
To assess endograft infolding for excessive bird-beak configurations in the aortic arch in relation to hemodynamic variables by quantifying device displacement and rotation of oversized stent-grafts deployed in a phantom model.


METHODS
A patient-specific, compliant, phantom pulsatile flow model was reconstructed from a patient who presented with collapse of a Gore TAG thoracic endoprosthesis. Device infolding was measured under different flow and pressure conditions for 3 protrusion extensions (13, 19, and 24 mm) of the bird-beak configuration resulting from 2 TAG endografts with oversizing of 11% and 45%, respectively.


RESULTS
The bird-beak configuration with the greatest protrusion extension exhibited the maximum TAG device displacement (1.66 mm), while the lowest protrusion extension configuration led to the minimum amount of both displacement and rotation parameters (0.25 mm and 0.6°, respectively). A positive relationship was found between the infolding parameters and the flow circulating in the aorta and left subclavian artery. Similarly, TAG device displacement was positively and significantly (p<0.05) correlated with the pulse pressure for all bird-beak configurations and device sizes. However, no collapse was observed under chronic perfusion testing maintained for 30 days and pulse pressure of 100 mm Hg.


CONCLUSIONS
These findings suggest that endograft infolding depends primarily on the amount of aortic pulsatility and flow rate and that physiological flows do not necessarily engender hemodynamic loads on the proximal bird-beak segment sufficient to cause TAG collapse. Hemodynamic variables may allow for identification of patients at high risk of endograft infolding and help guide preventive intervention to avert its occurrence.
Fondazione Ri.MED, Palermo, Italy Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy spasta@fondazionerimed.com.
Salvatore
S
Pasta
DICGIM, Universitá di Palermo, Italy.
Francesco
F
Scardulla
DICGIM, Universitá di Palermo, Italy.
Antonino
A
Rinaudo
Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
Giuseppe Maria
GM
Raffa
Cardiovascular Medicine Clinical and Research Unit, Vivantes Klinikum im Friedrichschein und Am Urban, Berlin, Germany.
Giuseppe
G
D'Ancona
Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
Michele
M
Pilato
Cardiac Surgery and Heart Transplantation Unit, Department for the Treatment and Study of Cardiothoracic Diseases and Cardiothoracic Transplantation, Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
Cesare
C
Scardulla
D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001027:Aortography; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000295:instrumentation*; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation*; D005548:Foreign-Body Migration / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011673:Pulsatile Flow; D015607:Stents; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
bird-beak configuration; displacement; endograft; flow model; hemodynamics; in vitro experiment; patient-specific model; stent-graft collapse; stent-graft infolding; stent-graft oversizing; thoracic endovascular aortic repair