Endoleak stent-graft

Fan CM, Rafferty EA, Geller EC et al (2001) Endovascular stent-graft in abdominal aortic aneurysms The relationship between patent vessels that arise from the aneurysmal sac and early endoleak. Radiology 218 176-182... 

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. 

Key words stent graft, endovascular aortic repair (EVAR), abdominal aortic aneurysm (AAA), endoleak, fenestrated graft. 

The contralateral limb component is deployed separately. It is designed to be 10-25% oversized in relation to the iliac artery s inner diameter to ensure affixation and reduce the risk of endoleaks. It is also flared on the proximal end in an open web configuration for the same reason. The friction between the inside of the contralateral stub and the outside of the contralateral limb is all that joins the two together, so the oversizing is key to ensuring a proper fit and no migration. The Valiant is Medtronic s latest thoracic stent-graft. 

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. 

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. 

Sandmann and Pfeiffer (2002) carried out a survey of 2,030 patients after EVAR due to abdominal aortic aneurysm. Within the first 4 years, 38% of patients had to undergo reintervention due to comphcations of the stent graft. The most common comphcations are endoleaks (Fig. 23.9), with a rate of 10% after 18 months. Endoleaks are generally classified into five types ... 

In the endovascular aneurism repair, a stent is placed, via percutaneous pathways, inside the aneurism sac in order to exclude it fiom the systemic pressure that can lead to burst of the sac (Fig. 11.19B). Although this may be the preferred approach (when possible) and proven to be successful, it is not free from postoperative issues, namely stent displacement or endoleaks (Katzen and MacLean, 2006). It is the latter that served as a pranise for the design of a smart stent graft (Sepulveda, 2013). 

---