Physician Modified Endograft For Complex Aortic Aneurysm Repair

The physician modified endograft is intended for treating complex, pararenal, juxtarenal and thoracoabdominal aortic aneurysms requiring coverage of renal arteries, the superior mesenteric artery or the celiac trunk in high-risk patients who do not have an option for endovascular repair with an FDA approved endograft and have an appropriate anatomy. There will be one investigational site with a total of 40 subjects to be enrolled. Time to complete enrollment will be 24 months and the subject follow-up time will be five years from last subject enrollment.

The primary safety endpoint is freedom from major adverse events (MAE) at 30 days or during hospitalization if this exceeds 30 days. The primary effectiveness endpoint is the proportion of study subjects with treatment success at one year. The subjects will be followed at one month, six months, one year, and yearly thereafter for a total period of five years. Subjects will be followed up clinically for life. Clinical exam follow up may be phone or video visit with CT scan evaluation and duplex ultrasound as needed. The proportion of treatment group subjects that achieve and maintain treatment success annually to five years will be investigated.

The devices that will be used are Cook Medical © devices designed and approved for thoracic aortic and perivisceral aortic disease. These devices are all constructed of full-thickness woven polyester fabric sewn to self-expanding stainless steel or nitinol Cook-Z stents with braided polyester and monofilament polypropylene suture. The grafts are available in a straight or tapered configuration, both of which are fully stented to provide stability and the expansile force necessary to open the lumen of the graft during deployment. These include Zenith TX2 Dissection Endovascular Grafts, The Zenith Alpha Thoracic Endovascular Graft and the Zenith Fenestrated Abdominal Aortic Aneurysm (AAA) Endovascular Graft. These are all modular components that can be modified in a similar fashion. These can be used in conjunction with extension pieces for the Fenestrated AAA endograft system to extend into the iliac arteries.

The goal of this IDE is to repair complex aortic aneurysms involving the visceral vessels (renal arteries, superior mesenteric artery and/or celiac artery) while maintaining a minimally invasive approach. This requires a patient specific approach to each graft in order to land in normal artery above and below the disease.

The majority of the aneurysms treated will fall into the thoraco-abdominal aneurysm classification but there will be perivisceral aneurysms that involve one or more of the visceral vessels as well. These will involve fenestrations if preservation of flow is required in a landing zone or branches if preservation of flow is in the middle of the repair. All of these types of aneurysms do not have FDA approved devices to treat them. The investigators propose an approach to these aneurysms of at least 2 cm of seal proximal and distal to the aneurysmal disease. As this requires branches or fenestrations to preserve flow to the vital visceral vessels. Achieving at least 2 cm of seal within the normal aorta or iliac arteries.

Using these tenants, the approach to a repair and device choice is as follows. The investigators will evaluate the CT scan of the patient with an aneurysm that is off IFU for any other device who is high risk for a traditional open repair. The investigators will then identify the proximal and distal landing zones. If they involve any of the visceral vessels to do a peri-visceral nature, then these will likely be planned to be fenestrations. If they are not in the seal zone but in the middle of the aneurysm they will be planned as branches. Device size selection is based on the landing zone diameter and based on the device IFU.

A staged approach may be used to minimize risks that may be associated with a single extensive repair or improve technical success. This may include but not limited to performing a TEVAR landing above the diseased aorta at least 2 cm into normal thoracic aorta or open aortic graft down to the level of the celiac artery, treatment of a dissection with either a dissection stent or septotomy, or preoperative stenting or embolization of stenotic vessels or accessory vessels that will be covered and excluded during PMEG implantation to prevent endoleak. The potential benefit of a staged approach is one of ischemic conditioning of the spinal cord or staged microembolization to the lumbar arteries in order to minimize ischemic events and space them out over two procedures allowing alternative flow to the spinal cord to improve. There is also a benefit of staging the amount of contrast and fluoroscopy required to perform all of these procedures minimizing the impact of potential radiation exposure to patient and operator and the risk of contrast induced nephropathy. The staged procedure will be 2-4 weeks prior to PMEG implantation.

Once the plan is made and the devices are selected, the main modified device is created on a back table while the patient is being prepared by anesthesia using a plan that is measured from a CT scan with 1 mm cuts or finer in order to have precise and accurate measurements of the following criteria for each vessel:

1. Diameter
2. Length to first major branch (that cannot be covered)
3. Arc length / clock location in comparison to reference vessel (SMA)
4. Longitudinal distance from reference vessel (SMA)
5. Angiographic view of the orifice of the vessel for optimal chance of cannulation
6. Size of the aortic flow lumen at the origin of the target visceral vessel
7. Degree of angulation at the vessel origin
8. Predominant trajectory of the vessel (lateral vs cranial vs caudal) Once this is done then the investigators deploy the appropriately sized endograft for modification on a back table. This graft is sized per IFU to the patient's aorta at the location of the landing zones. If the patient has challenging access (small external iliac artery diameters) then the device of choice for modification is more likely to be the Cook Alpha device as this has a lower profile for delivery ensuring technical success of this portion of the procedure minimizing access complications such as iliac dissection and rupture. Also if there are primarily or only fenestrations in the plan for repair, then the investigators will also likely consider or commit to an alpha device as this device has more space between stent struts and there is more difficulty resheathing it with branches due to the smaller sheath size. Otherwise the Cook ZDEG device will be modified as this also does not have a precurved nature to it allowing for more precise delivery and has less difficulty with the resheathing process. If the proximal landing zone is in the visceral segment of the aorta, then the investigators will use the Cook Fenestrated Zenith device as it has a built-in constraining wire and is built for a transfemoral approach for a juxtarenal AAA or pararenal AAA.

Modification Process

1. Deploy the graft on the sterile, surgical table
2. Mark out on the graft the locations of the fenestrations on the graft adjusting as necessary to avoid placing fenestrations over stents
3. Using handheld electrocautery, fashion the fenestration in the appropriate location on the moistened graft material in order to prevent inadvertent progression of the fenestration size
4. If the fenestration is going to remain as such, then an EV3 Gooseneck snare is used to fashion the marker on the fenestration with Gore 5-0 stitch
5. If the fenestration is going to be made into a branch, then an appropriately sized Gore, self-expanding stent is beveled and fashioned to be 15 mm long and sewn to the fenestration in addition to a EV3 Gooseneck snare with the Gore 5-0 stitch.
6. Two orientation markers are placed at the proximal edge and distal edge of the graft consisting of portions of the EV3 Gooseneck snare sewn to the anterior portion of the graft in a "J" fashion with a Gore 5-0 stitch.
7. The Graft is then sequentially constrained with care taken to ensure that the markers and branch orientation remain true.

Graft Implantation Process

1. Graft orientation markers and fenestrations are identified under fluoroscopy in an extracorporeal manner with rotation in order to ensure markers are in location both front to back and side to side. This is completed both prior to resheathing and after. This is again confirmed when inserted to the appropriate level in the body.
2. Using fusion imaging, the distal portions of the branches are put to 1-2 cm above the orifices of the arteries or fenestrations nearly at but slightly above the origins of the arteries.
3. Once the graft has been delivered to the appropriate location, the graft is unsheathed one aortic stent at a time until the first branch has been deployed.
4. Then from above, the vessels are sequentially cannulated with a wire and catheter with a catheter angiogram confirming the correct vessel.
5. The bridging balloon expandable Gore VBX stents are then delivered over wire maximizing overlap with the target vessel and the branch while flaring proximally 2-4mm into the main body of the endograft.
6. Once devices have been deployed, flow is ensured to be uninhibited by stenosis or dissection with a selective angiogram and then the endo grafting is extended distally into a previously placed endograft, normal aorta or surgically replaced aorta.
7. Once completed another completion angiogram is performed to ensure flow through all the branch vessels, and no major correctable endoleaks.