The procedure step by step: Which are

The procedure step by step: Which are the critical moments and what should be avoided?

In this step-by-step guide, Konstantinos P Donas outlines the chimney endovascular aneurysm repair (ChEVAR) technique from access to further treatment considerations, detailing various crucial moments and offering a range of tips and tricks to ensure a successful procedure.

THE CHEVAR TECHNIQUE increases the risk of occlusions is demanding and requires due to the placement of more advanced endovascular skills. material in a small (6mm or less) It involves a minimum of two target vessel. access points: femoral and The second critical moment is an upper extremity. Femoral to deploy the chimney graft in access can be completed in a the middle of the suprarenal stent percutaneous fashion. One or both of the abdominal device (Figures upper extremities, preferably the 1–3). The chimney graft should left side, are accessed dependent be protected and not be in contact on the number of chimney grafts Konstantinos P with the pins of the suprarenal planned. A preoperative computed Donas stent. In the removal of the tomography angiography (CTA) balloon of the chimney graft after of the thoracic aorta and the subclavian deployment in particular, the sheath should arteries is paramount in order to exclude be below or just at the level of the pins of the the presence of soft plaques and thrombotic suprarenal stent, protecting the balloon of lesions, which can lead to stroke or the chimney graft from the pins in order to embolisation of the visceral arteries. avoid the risk of trapping the balloon with the

An open approach to the axillary artery suprarenal pins of the abdominal device. is utilised in the majority of cases. We gain The next crucial moment is to perform proximal and distal control of the axillary artery, and single or double puncture of the vessel can be performed at a distance of The ChEVAR 1–2cm. After changing the short 5F sheaths technique is for 90cm 7F sheaths, we perform a selective catheterisation of the involved target vessels. demanding and Here is the first critical periprocedural requires advanced moment; the sheath followed by the chimney graft should be advanced in the target vessels endovascular skills.” only over a stiff wire with an atraumatic curved tip. Particularly where there is friction or stenosis of the orifice of the target kissing ballooning between the aortic stent vessels, there is a risk of injury to the kidney graft and the chimney graft at the end of the parenchyma when using stiff wires with stiff procedure. This manoeuvre is very important tips. because it improves the conformability of the

Once the selected branches have wires in abdominal device and the chimney grafts. place, the aortic endograft is deployed and, Here it is crucial to deflate the balloon of subsequently, each chimney graft should the chimney graft only after the complete have the proximal edge in the middle of deflation of the balloon in the aortic stent the suprarenal stent of the aortic endograft, graft. Otherwise, there is a risk of creating a extending at least 10–15mm inside the target stenosis of the chimney graft, which is not vessel. Angulated renal arteries are at risk of per se crush resistent from the balloon of the severe stenosis and kinking of the chimney aortic stent graft if the balloon of the chimney grafts, in the case of deep placement and graft is deflated first. involvement of the angulated segment of The next crucial moment during the the renal arteries. Additional deployment procedure is the reaction of the physician in of flexible nitinol stents or covered stents case of type Ia endoleak at the completion

Figure 1. There is a risk of complication from trapping the sheath with the pins of the suprarenal stent.

Figure 2. There is a risk of capturing the balloon of the chimney graft with the pins.

Figure 3. The ideal position of the sheath, protecting the balloon from the pins, for when we decide to remove the balloon.

angiography. How aggressive should further treatment be; should we deploy a cuff; should we use endoanchors or not? The main rationale for the decision is to admit that type Ia endoleaks caused by the gutters is common during the procedure. The question is, which case will need additional treatment and which case will undergo radiological surveillance?

Preoperative planning is key to the eradication of potential gutter-related endoleaks. As clarified in the previous article from Fazzini, aggressive oversizing of 30% in single chimneys and 35% in double chimneys, and a new seal zone of at least 20mm in length, are important considerations in preoperative planning. Within these parameters, any gutter-related endoleak at the completion angiography will dissapear in the in-hospital CTA.

Konstantinos P Donas is professor of vascular surgery, head of the Department of Vascular Surgery, and director of the Research Centre at Asklepios Clinic Langen, Göthe-University Frankfurt, Langen, Germany.