A New Design for Aortic Arch Surgery: Ex Vivo Implantation and Computerized Flow Evaluation of the ISLAND Graft

Both the en bloc island technique and the branched graft technique (BGT) present advantages but also limitations in aortic arch surgery. Here is the first presentation of an innovative prosthesis for aortic arch replacement, conceived to overcome the disadvantages of both techniques.

The novel ISLAND graft is a tubular Dacron or hybrid prosthesis with an additional extended Dacron graft ("bubble") on the superior aspect, for en bloc island graft anastomosis. To verify the technical feasibility, following bench study, 3 prostheses were implanted in human cadavers in which the distal anastomosis was performed either in zone 2 or 3. A flow analysis and a computational simulation were performed in different configurations. The flows of the "full-bubble," the "cut-bubble," and the traditional branched grafts were compared. The wall shear stress, time-averaged wall shear stress (TAWSS), oscillatory stress index (OSI), and relative residence time (RRT) were compared in the 3 settings.

The novel prosthesis appeared easy to implant with significant technical advantages. The manipulation of epiaortic vessels was reduced with expected lower risk of neurologic events. The fenestration of the external cuff could be tailored to the island segment, thus eliminating most pathological aortic tissue. The flows in the supraortic branches were more favorable in the ISLAND graft, in which the angles of the branches were maintained, and with reduced cuff height (cut-bubble), in which higher values of TAWSS and lower values of OSI and RRT were calculated.

The novel ISLAND graft device overcomes the disadvantages of the traditional island technique and benefits from the advantages of the BGT. Given the first results, the next step would represent the in vivo implantation.