Abstract 246: Evaluation of 2-Dimensional Aortic Arch Motion at the Origin of the Left Subclavian Artery: Importance of Respiratory Motion

Abstract

Introduction: Interactions between components of branched thoracic main stent grafts (MSG) and branch stent grafts (BSG) in the arch have not yet been evaluated. As the chest is subject to both cardiac and respiratory motion, the purpose of this study is to evaluate the cardiac and respiratory effects on interactions between components in the aortic arch. Methods: Two swine had a BSG alone placed in the LSA and two had an MSG/BSG system placed in the LSA. Frames representing the extreme positions of the BSG due to cardiac imposed motion during apnea and through the respiratory cycle were identified in 2-D cines. These images were overlaid as layers, using external reference markers common to each image for accurate overlay positioning. The BSG’s were traced and magnitudes of horizontal and vertical bulk displacements were quantified to evaluate cardiac (CM) and respiratory (RM) [deep inspiration (30 mmHg)]. Relative motion was extracted from bulk motion by comparing displacements at the top and bottom of the BSG. Results: RM resulted in significant difference in bulk horizontal motion compared to CM for the BSG [5.65 + / - 0.07 versus 3.15 + / - 0.63mm, (p=0.002)] and was nearly significant for the MSG /BSG system [4.25 + / - 0.07 versus 2.3 + / - 0.42mm, (p=0.061)]. RM resulted in significant difference in bulk vertical movement compared to CM for the BSG [2.2 + / - 0.28 versus 0.85 + / - 0.35mm, (p=0.026)] and the MSG/BSG system [2.05 + / - 0.07 versus 0.6 + / - 0 (p=0.000001)]. The MSG presence significantly dampened bulk horizontal movement for RM [4.25 + / - 0.07 versus 5.65 + / - 0.07mm, (p=0.0013)] but had no effect on vertical movement [2.05 + / - 0.07 versus 2.2 + / - 0.28mm, (p=0.15)]. RM resulted in significant difference in relative horizontal motion compared to CM for the BSG [4.25 + / - 0.49 versus 2.7 + / - 0.28mm, (p=0.014)] and the MSG/BSG system [1.85 + / - 0.07 versus 0.95 + / - 0.35mm, (p=0.0048)]. RM resulted in significant difference in relative vertical movement compared to CM for the BSG [1.25 + / - 0.07 versus 0.3 + / - 0.28mm, (p=0.002)] and MSG/BSG system [0.7 + / - 0.14 versus 0.25 + / - 0.21mm, (p=0.03)]. The MSG presence significantly dampened relative horizontal and vertical movement for RM [1.85 + / - 0.07 versus 4.75 + / - 0.49mm, (p=0.0004)] and [0.7 + / - 0.14 versus1.25 + / - 0.07mm, (p=0.02)], respectively. Conclusions: RM adds considerably to bulk and relative motion, with horizontal motion dominating. Relative motion accounts for high percentage of bulk motion. The presence of the MSG dampens motion considerably. This is the first study to account for the effects of respiratory motion on branched endografts in the aortic arch. This movement should be taken into account when developing a MSG/BSG for the therapy of aortic arch aneurysms.