Physician-Modified Endografts for Complex Aortic Aneurysms and Thoracoabdominal Aneurysm Repair in High-Risk Patients

The devices employed in this study are Cook Medical products designed and approved for the treatment of thoracic and abdominal aortic diseases. These devices are constructed with full- thickness woven polyester fabric sewn to self-expanding stainless steel or nitinol Cook-Z stents, utilizing braided polyester and monofilament polypropylene sutures. Available in straight or tapered configurations, both variants are fully stented to ensure stability and the required expansile force for lumen opening during deployment. The devices encompass the Zenith TX2 dissection endovascular grafts and the Zenith Alpha thoracic endovascular grafts. These modular components are used in conjunction with other endovascular grafts to establish suitable proximal and distal sealing zones.

The selection of graft sizes is based on findings from preoperative radiologic studies, including computerized tomography (CT) and, if necessary, conventional angiography. Sizing of Zenith endovascular devices adheres to their respective instructions for use. The chosen outside diameter of the Zenith endovascular graft should be 15-25% larger than the proximal

implantation site. Similarly, the attachment site for the distal implantation is oversized by approximately 15-25%. This optimal graft-to-vessel diameter ratio aims to enhance the likelihood of achieving a secure seal with the vessel wall, mitigating the risk of graft migration, endoleaks, and thrombosis.

The majority of cases involve thoracoabdominal aneurysms, with some encompassing paravisceral and pararenal aneurysms. For the former, fenestrations will be used to preserve flow to visceral vessels, while the latter will involve branches to maintain flow. The goal is to achieve at least 20mm of seal within the normal proximal aorta and 15mm of seal distally in the iliac arteries.

Branches will primarily be used where the aortic diameter at the level of the visceral or renal branches is \>28mm in size. When branches are to be used, 6-8mm fenestrations will be burned 20mm above the target vessel based on centerline measurements described above. A branch will be created by cutting a self-expanding Gore Viabahn stent to 15mm in length and suturing this onto the fenestration in a running fashion using a Gore-Tex suture. The size of the fenestration and the size of the Viabahn stent will be patient on target vessel size and will be created accordingly.

Determination of the proximal graft diameter and graft sizes depends on the measurement of the aneurysm using centerline flow measurements based on axial reconstructions of CT data. All measurements will be made with multi-planar reconstruction (MPR) perpendicular to the long axis of the neck to provide greater understanding of the aneurysm neck diameter. The diameter of all vessels, length to first major branch that cannot be covered, arc length/clock location in comparison to reference vessel (celiac artery), longitudinal distance from reference vessel (celiac artery), angiographic view of the orifice of the vessel for optimal chance of cannulation, size of the aortic flow lumen at the origin of the target visceral vessel, degree of angulation at the vessel origin, and predominant trajectory of the vessel (lateral vs. cranial vs. caudal) will all be recorded in preoperative case planning. The lengths of the proximal, distal and extension components of the appropriate Cook stent graft will be chosen to achieve a recommended minimum of two stent overlap, with three to four stents overlap when possible.

The choice between the Zenith Alpha and TX2 devices depends on the patient's specific circumstances. The Zenith Alpha device is preferred in cases of challenging access (small external iliac artery diameters) to minimize access complications. Additionally, if primarily or only fenestrations are required, the Zenith Alpha device will be chosen due to its more favorable geometry. Otherwise, in the case where branches are chosen, the Cook TX2 device, will be modified due to the ability to presheath branches in a more facile manner.

When branches are to be used, 6-8mm fenestrations will be burned 20mm above the target vessel based on centerline measurements described above. A branch will be created by cutting a self-expanding Gore Viabahn stent to 15mm in length and suturing this onto the fenestration in a running fashion using a Gore-Tex suture. The size of the fenestration and the size of the Viabahn stent will be patient on target vessel size and will be created accordingly. When

fenestrations are used, they will be reinforced with the En Snare endovascular snare using 3-0 ethibond sutures in a running locking manner.

At the physician's discretion, commercially available, off-the-shelf covered stents, specifically, the Atrium Medical Corporation iCAST stent graft (Hudson, NH) the Gore VBX Endoprosthesis or Gore Viabahn (Flagstaff, AZ), may be used to stent visceral vessels targeted by a fenestration. Visceral vessel anatomy and relative orientation will be determined from the imaging data. Important characteristics include the relationship of the renal arteries, the distance between them and the SMA, and the relationship between the celiac and SMA. Careful consideration of angulation is needed, with ostial angles primarily established from axial views, and distances calculated using axial information as well as reconstructions. The diameter of the stent should be 1.0-1.1 times the reference vessel diameter as determined by imaging data. The length of the stent should be selected so that the distal end of the stent does not cross the bifurcation of the targeted vessel.

In the setting of branch vessel tortuosity, bare metal self-expandable stents, specifically the Abbott Vascular Absolute Pro® (Santa Clara, CA), may be used to transition the covered stent graft into the curvature of the target vessel. In addition, the Gore VBX Endoprosthesis (Flagstaff, AZ) platform is much more trackable through curves than the iCAST stent graft (Hudson, NH), enabling stent graft delivery through a steerable sheath, from the groin, for down-going branches. In contrast, the relative stiffness of the iCAST platform makes delivery of the stent graft through a steerable sheath, from the groin, for down-going branches, impossible or extremely difficult.

The proximal edge of a fenestration stent graft will be placed such that 4 mm of stent graft extends into the aortic endograft lumen. This proximal edge will be flared with a Boston Scientific Mustang™ Balloon Dilation Catheter (Maple Grove, MN) to create a seal at the fenestration site. In terms of branches, the proximal edge of the bridging stent will extend 2mm proximal to the suture point of the Viabahn branch that was sutured in place.

In patients who require extensive coverage, procedures will be staged in 2-3 stages, with extent 1 thoracoabdominal aneurysms being repaired in 2 stages, and extent 2 thoracoabdominal aneurysms being repaired in 3 stages. Depending on the location of the landing zone, and size and characteristics of the landing the zone, the proximal landing zone will be the Gore thoracic branch endoprosthesis for aortic pathology requiring zone 2 landing zone, and Cook Alpha or Cook TX2 for zone 3 and 4 landing zones. The Cook Alpha/Cook TX2 will be the modified portion for the visceral component, and in order to minimize device modification, a Gore Excluder will be used as the infrarenal device, with the Gore Iliac Branch Endoprosthesis being used for patients who also have common iliac artery aneurysms.

Like with like devices will be preferentially used whenever possible, and proximal and distal extension will only be used if the devices to not have adequate characteristics to achieve proximal or distal seal.

Patients with extent 1 thoracoabdominal aneurysms will be repaired in 2 stages, with the proximal device being Gore thoracic branch endoprosthesis for aortic pathology requiring zone 2 landing zones, and Cook Alpha or Cook TX2 for zone 3 and 4 landing zones.

For patients with extent II thoracoabdominal aneurysms that require zone 2 or 3 repair, our preference is to split these into 2 procedures, with the first being TEVAR, the second being physician modified endograft and EVAR with/without iliac branch endoprosthesis. In cases without use of the iliac branch endoprosthesis, we plan on using the Gore excluder iliac limbs in order to complete the repair. We believe that this is the safest and most effective way to repair complex extent II thoracoabdominal aneurysms with common iliac disease.

In cases where the Gore Thoracic Branched Endoprosthesis is used for zone 2 seal, distal extension device will either be a Gore Conformable Thoracic Aortic Endovascular Graft (CTAG) or Cook Alpha or TX2, depending on patient anatomy.. This is the only situation where the Gore Conformable Thoracic Aortic Endovascular Graft (CTAG) will be used.

The following methods and materials employed for modifying the Zenith platform mirror those described by Starnes and Oderich. The principal investigator of this proposal as well as the other sub investigators, possess substantial training under Dr. Oderich. This method of physician modification has been successfully implemented in our prior experience at the University of California Davis for creating fenestrated and branched endografts to treat complex aneurysms. The materials utilized in this technique, such as sterile marking pens, ophthalmic cautery, En Snare endovascular snares, prolene sutures, silk sutures, Gore Viabahn self-expanding stents, Gore-Tex sutures, silastic vessel loops, and peel-away sheaths, have established clinical history for such modifications.

1. Following the procedure outlined by Oderich in 2010, each patient's device will be selected in adherence to standard instructions for sizing guidelines. The graft will be unsheathed on a separate table in the operating room. 2. Subsequently, investigators will employ a sterile marking pen to delineate fenestrations or branches' locations based on pre-established length, clock face, and arc angle measurements derived from reconstruction software, as described above. 3. Minor adjustments will be executed in the fenestration area to optimize strut-free fenestrations' utilization whenever feasible. Utilizing an ophthalmic cautery device, the Dacron fabric will be meticulously cauterized. En Snare endovascular snare (Merit Medical, Jordan UT) will reinforce fenestrations, securely hand-sewn into place using 4-0 prolene sutures in a 720-degree running fashion. If a fenestration will serve as a branch, a properly sized Gore self-expanding Viabahn stent will be fashioned, approximately 10-15mm long, and sewn onto the fenestration using Gore 5-0 or 6-0 Stitch. An orientation marker will be placed at the proximal graft edge, and two markers at the distal edge, utilizing Gore stitches. 4. Diameter reducing ties are then used to constrain the device along its posterior border (opposite the SMA and or celiac fenestrations at 6 o'clock) by rerouting one of the existing trifold wires through the graft material at the midpoint of each of the Z stents. The constraining ties are then put down into place over the wire, and the goal is the diameter to be reduced by approximately 60%. 5. The modified device is then resheathed by constraining each stent with a silk tie. Once constrained, the device is serially resheathed using silk tie and a large silastic vessel loop to transition back to the diameter of the original delivery sheath in which the device was packaged. Care is taken to ensure that the markers and branch orientation remain true.

The procedure will be performed in the operating room under local, general, or epidural anesthesia depending on patient factors and agreement of anesthetic plan by the patient, the surgery team, and the anesthesia team. The patient will be positioned on a radiolucent operating room table to permit fluoroscopic examination of the

• Evidence of Aortic Disease Progression [Срок оценки: 5 years]
• Device Failure [Срок оценки: 5 years]
• Endoleaks [Срок оценки: 5 years]
• Secondary Interventions [Срок оценки: 5 years]
• Significant Lifestyle-limiting or disabling complications [Срок оценки: 5 years]
• Cardiac dysfunction [Срок оценки: 5 years]
• Renal events [Срок оценки: 5 years]
• Mesenteric Events [Срок оценки: 5 years]
• Respiratory events [Срок оценки: 5 years]