Frailty and Physician Modified Fenestrated Endograft for Thoracoabdominal Aortic Pathologies

Device Description

Two types of commercially approved thoracic aortic stent-grafts will be modified under the aegis of a physician-sponsored IDE protocol (G200159). The Cook (Bloomington, IN) Zenith Alpha proximal tapered mainbody thoracic stent-grafts and the Cook Zenith TX2 proximal tapered mainbody will be modified to form the fenestrated/branched aortic components. The Alpha thoracic stent-grafts are constructed of woven polyester graft sewn to discrete rows of self-expanding Nitinol Z stents. The most proximal sealing stent is located internally with fixation barbs that protrude through the graft material. The second proximal stent is straight, and the third stent is tapered by 4mm in diameter.

The diameter of the TX2 proximal tapered stent-grafts will range from 32mm to 42mm, depending on the size of the aorta at the proximal seal zone. The lengths will range from 154 to 210mm. The TX2 thoracic stent-grafts are constructed with woven polyester graft sewn to discrete rows of self-expanding stainless steel Z stents. The most proximal seal stent is sewn inside the polyester fabric. The third stent is tapered by either 4mm or 8mm in diameter.

The modification design will be planned using a 3-D multiplanar reconstruction analysis of the CT angiography. Proximal seal zone will be chosen at 2cm disease free parallel aortic walls. Target vessel position will be determined by the longitudinal distance between the proximal extent of the seal zone to the middle of the vessel orifice, as well as radial clock position. Based on these measurements, patient specific modification map will be constructed.

The modification will be designed to incorporate visceral and renal branches, utilizing a various combinations of fenestrations and branch cuffs. The choice between fenestrations and branch cuffs will be made based on the aortic size and angulation at the level of the target branches. For example, when the target branches are within the seal zone, fenestrations will be chosen. Conversely, branch cuffs will be incorporated onto the mainbody if the aorta at the level of the target branches is aneurysmal, or angulated where precise three dimensional position of the target branch, hence fenestration, along the implanted stent graft is difficult to predict.

Modification Technique

Modification will be performed on the day of the operation using strict sterile technique. Tapered low profile Cook Zenith Alpha proximal component thoracic stent grafts will be unsheathed. One of the trigger wires is retrieved from the inner cannula of the delivery system, to be used as a diameter constraining wire. This wire is rerouted posteriorly through and through the fabric of the stent graft using a long 22-gauge needle.

Fenestrations at planned locations will be created using an ophthalmic cautery, and reinforced with a double layer of Amplatz Gooseneck Snare (Medtronic, Minneapolis, MN) wires made up of braided Nitinol. The wires will be secured around the fenestration by tightly spaced 5-0 Ethibond (Ethicon, Somerville, NJ) locking sutures. Additional radiopaque markers will be sutured around each fenestration. When necessary, directional branch cuffs will be created by fashioning 8mm or 6mm Viabahn self expanding covered stents (Gore & Associates, Flagstaff, AZ) into 2cm long side branch cuffs. The branch cuffs will be sutured to the oval fenestration created on the aortic stent grafts by running 5-0 Goretex sutures. Radiopaque markers will be sutured around the entrance and exit of each branch cuff.

Prior to resheathing, the posterior aspect of Z-stents are constrained using loops of prolene sutures as diameter reducing ties. Proximal fixation barbs will be removed using a wire cutter. Fenestrations and branches designed to be catheterized from the brachial approach will be pre-wired with 0.014 inch guidewires. The modified stent graft will be resheathed using 2-0 Silk ties and Umbilical tapes.

Inclusion criteria

• Patients may be included in the study if the patient has at least one of the following indications and are anatomically appropriate for treatment with fenestrated/branched stent grafts.

• Pararenal, paravisceral, and type I to IV thoracoabdominal aortic aneurysms or chronic post-dissection aneurysms with a diameter 5cm or 2 times the normal aortic diameter.
• Aneurysm with a history of growth ≥ 0.5cm per year.
• Saccular aneurysms deemed at significant risk for rupture based on physician interpretation.
• Symptomatic aneurysm without hemodynamic instability
• Aneurysms meeting any of the above criteria 1~4, above or below the previous endovascular and/or open aortic repairs. Previously placed aortic stent graft or open aortic grafts may serve as seal zones.

Exclusion criteria

• Patients must be excluded from the study if any of the following conditions is true:

• Less than 18 years of age.
• Unwilling to comply with the follow-up schedule.
• Inability or refusal to give informed consent by the patient or a legally authorized representative.
• Pregnant or breastfeeding.
• Life-expectancy less than 2 years.
• Participation in another investigational clinical or device trial, with the exception of participation in another investigational endovascular stent-graft protocol and performed remotely from the fenestrated procedure (>30 days). Examples include remote (>30days) participation in a thoracic, or abdominal branch device trial.
• Eligible for treatment with FDA-approved marketed device.
• Eligible and willing to travel to a center with IDE protocol wherein the device is made by a manufacturer.