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Does the AAA stent-graft industry need proximal fixation? How is the next innovation in an Aortic Aneurysm repair kit going to look like? Does the kit to fix stent-grafts include proximal fastener and endoleak fixation devices?

Of the 2 million patients in the USA estimated to have abdominal aortic aneurysmal disease (AAA), only 25% of all patients are diagnosed and just 5% receive some form of treatment. Ever since the Screening AAAs Very Effectively (SAAAVE) Act became law in January 2007, more Abdominal aortic aneurysms (AAA) can be identified pre-rupture by physical exam or by ultrasound. Most vascular surgeons recommend conventional open surgical repair for good-surgical-risk patients but endovascular stent-graft repair (EVAR) is still being recommended for elderly AAA patients who have suitable anatomy for stent-graft placement with an infrarenal neck long enough and a suitable diameter for the device to be placed.

Stent-grafts rely on a secure attachment to the proximal neck of an aneurysm, but several factors can interfere with this attachment. The neck contracts and expands as blood flows through the vessel. The portion of the neck closest to the spine remains relatively fixed while the remainder of the vessel expands and contracts in response to the changing blood pressure during normal pulsatile flow. This circumferentially dynamic expansion and contraction of the neck presents problems for attachment systems that expand and contract evenly around the entire circumference. Calcification prevents ingrowths of the graft and the aneurysm neck length varies and is often short.

The durability of the stent-graft AAA repair procedure is still under study and stent-graft repair has not convincingly proven to reliably prevent aneurysm rupture over a long-term follow-up with randomized, prospective clinical trials. The EuroStar registry (a multicenter experience of 35 countries) suggests that up to one third (33%) of stent-graft patients may require secondary procedures to maintain device patency or to treat endoleak.

Because of the risks associated with stent-graft endoleaks and stent-graft device durability, regular follow-up procedures for stent-graft patients are mandatory. One of the U.S. market giants in stent-grafting has recently acquired another fastener technologies in an attempt to provide a solution for secure proximal fixation. The latest acquisition is a repositionable surgical clip for vascular surgery that had limited success on the European market place. The endoluminal fastener has a low profile device which delivers a repositionable clip. The new vascular fastener is an implantable clip and delivery system that is intended to assist in the creation of anastomoses in blood vessels, grafts, and the surgical approximation of the stent-graft to the aortic wall. The fasteners are made out of a single monofilament Nitinol wire which is sharpened at both ends. The two branches of the fastener are curved as in a bow and separated via a loop wire in the center.

The first 10 clinical cases using the endoluminal nitinol fastener will have to go well in order for an potential U.S. distribution agreement. However, at the time of actual clinical application of such an endovascular nitinol clip device, the major obstacle is to make sure that the clip actually penetrates through both, the stent-graft and the neck of the aneurysm wall and not get deflected by calcified deposits. The endoluminal application and delivery of the device needs to be more accurate than inflating a balloon in order to navigate the device under fluoroscopic vision to the endoleaks. Endoluminal stapling device have been shown in this blog with all design limitations of which many can be applied to the described attempt to provide proximal fixation devices for endoluminal repair techniques.

Further - the future ain’t what it used to be.
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