Model geometry

The simple procedures of RVR with unilateral and bilateral CIA are:

For unilateral CIA, one quar-furcated graft was constructed, and the main body side of a quar-furcated graft was anastomosed end-to-side to a unilateral CIA with a 5–0 Prolene suture to serve as the visceral inflow blood source. The four limbs of the graft were respectively anastomosed, end-to-side, to the right renal artery, superior mesenteric artery (SMA), celiac artery (CA) and left renal artery (LRA) with a 6–0 Prolene suture[3].

For bilateral CIAs, two bifurcated grafts were chosen, and the main body side of one bifurcated graft was anastomosed end-to-side to a right CIA that served as the visceral inflow blood source. The two limbs of the graft were respectively anastomosed end-to-side to right renal artery (RRA) and CA. The other graft was constructed from a left CIA to SMA and LRA (Fig 1).

Left: the preoperative CTA image of TAAA; Middle: the retrograde revascularization from bilateral CIA; Right: The angiography of DSA for the RVR with bilateral CIA following hybrid treatment.

The bifurcated vessel prostheses (Gore-TEX) of 16mm×8mm were actually selected for the bypass graft of RVR based on the experience in the West China Hospital. The vessel prostheses (Gore-TEX) of 16mm×8mm were more suitable to Asian populations than the prostheses of 18mm×9mm because of the smaller diameter of arteries in Asian populations[17]. Further, two 8mm grafts were respectively sewn side-to-end to the main body of the 16×8mm Y-shape bifurcated graft, thus allowing the tetrachotomous graft to be constructed. Finally, the inflow diameter of the bypass graft model was 16mm and the outflow diameter was 8mm.

The model geometry was built using software Pro/E 5.0 (PTC Inc., Massachusetts, USA). Based on the postoperative computer tomography angiography (CTA) or DSA of patient with TAAA[3], the normal abdominal aortas (AA) [18] and AA with visceral grafts connected to the iliac arteries shown were constructed (Fig 2).The aorta tapered uniformly from a circular cross section with a diameter of 22mm at the supraceliac aorta to a circular cross section with a diameter of 16mm at the aortic bifurcation. The take-off angles of both iliac arteries at the bifurcation were 30°. The idealized AAs with visceral branches were constructed referring to the average data of other healthy Chinese cases[17,18] (Fig 2A). To simplify the modeling, the decimal values were omitted for the numerical values of the diameters. When a quar-furcated graft was connected to the left common iliac artery (LCIA), the diameters of the bypass and debranching grafts were 16 mm and 8mm respectively (Fig 2B). When two bi-furcated grafts were connected, the diameters of the bypass and visceral grafts were all 8mm (Fig 2C). To make a fair comparison, the anastomosis angles between the host artery and the graft were all set to be 45°.

A) Structure of normal AA; B) RVR using unilateral quar-furcated graft; C) RVR using bilateral bi-furcated grafts. CA-celiac artery, LRA-left renal artery, RRA-right renal artery, SMA- superior mesenteric artery, LCIA-left common iliac artery, RCIA-right common iliac artery.