The Tolerance for Misalignment When Repairing Standardized Multi-Branched Thoracoabdominal Stent Grafts

ABSTRACT

PURPOSE: We wanted to assess the accuracy of thoracoabdominal stent graft deployment and the effect of the stent graft orientation on the angulation of the visceral branches. METHODS: The accuracy of thoracoabdominal stent graft deployment and the effect of the stent graft orientation on the angulation of the visceral branches were assessed. The actual cuff orientation (ACO), the actual vessel orientation (AVO) and the longitudinal branch length (LBL) were measured by 3-dimensional analysis (TeraRecon) of the postoperative CT scans. The ACO was compared with the planned orientation (PCO) to assess malorientation (ACO-PCO). The ACO was also compared with the AVO to assess the branch angulation in the trans-axial (ACO-AVO) and longitudinal branch angle (LBA) planes. RESULTS: Between Nov 2005 and Dec 2008, 38 patients underwent multi-branched endovascular aortic aneurysm repair with a total of 136 branches to the visceral arteries. Small degrees of malorientation (ACO-PCO) were common, but severe malorientation (>45 degrees) was rare. The cuff-bearing portion of the stent graft usually rotated as a single unit. Only one patient had >30 degrees of twisting between the celiac artery (CA) and SMA cuffs and only 4 had >30 degrees between the CA and the left renal artery (LRA). Ninety one percent of the visceral arteries lay within a vertical 60 degree-wide arc (LBA x2) that was centered on the outer orifice of the corresponding cuff. All 141 branches were inserted as planned. None have migrated, disconnected or kinked. CONCLUSION: The branches of a thoracoabdominal stent graft do bend to accommodate a modest degree of malorientation, but these angles do not compromise the stability of the branch implantation.