Stent grafts devices

Table 21.2 Major commercial stent-graft devices for AAA andTAA repair... 

Anaconda device, 662-3 AneuRx device, 651-3 Aorfix device, 661 commercial stent-graft devices for AAA and TAA repair, 649-50 Cook Zenith Flex stent graft, 658 Endurant II and Valiant devices, 653-6... 

Carroccio A, Faries PL, Morrissey NJ, et al. Predicting iliac limb occlusions after bifurcated aortic stent grafting anatomic and device-related causes, J Vase Surg 2002 36(4) 679-684,... 

As mentioned above, status of the internal iliac arteries is an important anatomic consideration in the treatment of aortoiliac aneurysms. Indications for embolization of IIA in association with EVAR include aneurysm of the IIA or ectatic or aneurysmal common iliac artery (CIA) involving the origin of IIA. Additionally, extension of stent-graft into the external iliac artery (El A) may become necessary if the CIA is judged to be too short for adequate or safe anchoring of the device or if there is a distal type-I endoleak. This will lead to loss of antegrade flow in the IIA. 

For the deployment mechanism, most devices have a method to keep the stent-graft tethered until the physician is satisfied that he or she has positioned the device appropriately, before fully releasing and deploying the device. Some approaches have allowed the device to be reconstrained , so the device can be repositioned safely. 

The Medtronic Talent device is a stent graft constructed from a plain woven polyester fabric and a nitinol stent frame. The bifurcated device for the abdominal aorta has a bare suprarenal stent, but no hooks or barbs. The thoracic stent graft has been replaced by the Valiant device (see below). Early Talent devices had a rigid longitudinal bar that was meant to provide columnar support. However, this component signihcantly decreased the flexibility of the device, and so has been discontinued in more recent models. 

Mertens et al. (2011) looked at the long-term results of patients treated with the Zenith Flex stent graft. They analyzed 143 patients for overall survival, intervention-free survival, aneurysm rupture rates, early and late postoperative complications and endoleaks. At 5 years, 72.1% of patients and at 8 years 50.9% had survived. By 8 years 9% of patients (six total) had experienced a late aneurysm rupture, with three fatalities. Forty-seven patients experienced endoleaks, 18 of which were type 1,25 had one or more type II endoleaks (33 cases in total) and three type III one of these required a conversion to open repair and another required a bypass, indicating a defect in the stent graft material rather than an incomplete seal between the aortic limb stubs and the extensions. There was also one case of endotension and six cases of stent fracture. The authors in this study concluded that the Zenith Flex endograft is an excellent device with good long-term results and low aneurysm-related mortality. 

In 2010 Cook Medical launched a new three-piece modular device with an 18 Fr hydrophilic braided sheath and a lower-profile polyester woven graft fabric. While it has received its CE mark in Europe, it is still going through clinical trials in the United States. The TX2 is Cook s thoracic stent-graft. It also comes in a low-profile (LP) iteration. 

Currently there is only one prefenestrated endovascular stent-graft system approved by the FDA for use in the United States. It is an iteration of the Cook Zenith called the Cook Zenith Fenestrated . It is custom-made for each patient based on their personal aortic anatomy. This requires detailed CT scans of the abdominal aorta to properly locate the renal arteries and the superior mesenteric artery. The device is then manufactured with holes in the top piece for the renal arteries and a scallop at the top for the superior mesenteric artery (Fig. 21.19). These fenestrations are usually supported by a nitinol metal ring sewn around the circumference of the fenestration, as seen in the image taken from the study by Halak et al. (2006) (Fig. 21.20). 

Therefore, methods such as hybrid procedures, sandwiches, chimneys and snorkels, and on-site and in situ fenestrations have been developed. Hybrid procedures involve open surgery to create bypasses to the renal and mesenteric arteries, followed by covering all the branches with a conventional stent graft so as to extend the landing zone. Chimneys or snorkels involve placing a parallel, smaller sized covered stent into the renal arteries so that blood flows to the kidneys. However, there is concern that endoleaks will cause blood to flow between the aortic stent-graft and the renal chimney. There is a similar concern when more than one bifurcated device is inserted or sandwiched in the same aneurysmal sac so as to provide blood flow to several extensions simultaneously. The body of such devices needs to take on a D shaped cross-section so as to avoid endoleaks between the devices and the aneurysmal sac. 

FDA Recently-approved devices > Endurant stent graft system - P100021 Retrieved 7/3/2013, from http //www.fda.gov/MedicalDevices/Productsand Me dicalProcedures/De vice Appro valsandCle arances/Recently-ApprovedDevices/ucm240094.htm. 

Amplatzer Septal Occluder, 543 schematic diagram, 544 structure, 545 Anaconda device, 662-3 stent graft, 455,663 AneuRx device, 651-3 Talent stent graft, 652,653 two-component AneuRx bifurcated AAA stent graft, 652 aneurysm, 437 risk estimation, 644 anterior cruciate ligament anatomy and structure, 591-5 anteromedial and posterolateral bundles, 593... 

Fenestrated Anaconda device, 668-9 stent graft, 669 fibre diameter, 61-3... 

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