Fenestration Alignment Program

Technology

First, the program automatically calculates the fenestration coordinates and dimensions from preoperative imaging of the patient-specific implantation site and generates a 2D representation known as a fenestration mask. After the user selects a particular off-the-shelf endograft, the program renders a graft mask, or 2D representation, highlighting structural components, including stent struts. The fenestration mask is then successively convolved with the graft mask in both the longitudinal and circumferential directions until a valid fit, in which no proposed fenestration overlaps with graft structural components, is identified. The validated fenestration plan is mapped onto a 3D endograft model, which can be displayed in relation to the patient’s anatomy and reviewed by the surgeon. Finally, fenestrations are marked or created on the physical endograft using the coordinates from the fenestration plan. In an automated configuration, a graft may be positioned on a rotating rod or mandrel, while motor-driven positioning components move a marking, cutting, or cauterizing tool to each designated coordinate.

Problem Addressed

Complex aortic aneurysms that extend to or above the renal and visceral branch arteries often lack sufficient healthy aorta for a conventional endograft to achieve proximal seal without obstructing blood flow to the critical branch vessels. Fenestrated endografts can preserve perfusion through these vessels, but manufacturer-produced, patient-specific fenestrated endographs can require weeks to obtain and therefore are not suitable for urgent interventions. Customizing an off-the-shelf endograft instead requires surgeons to manually translate CT-derived vessel locations into fenestration positions, often through trial and error to avoid non-modifiable stent struts. The present technology automates the identification of valid, patient-specific fenestration alignments on commercial graft templates and produces modification instructions and a 3D visualization, reducing planning burden and supporting potential automated graft fenestration.

Advantages

• Substantially reduces planning time: In a pilot retrospective clinical study, FENFIT reduced average fenestration-planning time by approximately 62-fold, from about 30 minutes to 32 seconds per case, relative to physician manual planning.  
• Accommodates multiple graft geometries: The technology can support patient-specific fenestrated implants with either isodiametric or heterodimeric (tapered) geometries. For tapered grafts, the program can divide the graft into regions and seamlessly apply the appropriate coordinate system for each region during the mask-alignment process.
• Improves design review and clinical communication: A visual interface displaying the patient-specific graft design in relation to the underlying anatomy enables physicians to review, reference, and discuss the fenestration design.  
• Applicable across fenestrated implant types: The underlying planning method can be adapted to other fenestrated medical implants, including stents, vascular grafts, prosthetic valves, autologous, allogeneic, xenogeneic, synthetic, and hybrid stent-graft constructs.

Publications

Dillon, Tom M., Patric Liang, Marc L. Schermerhorn, and Ellen T. Roche. “A Computational Program for Automated Surgical Planning of Fenestrated Endovascular Repair.” Communications Engineering 2, no. 1 (2023): 37.