Back to Annual Meeting ePosters

OBJECTIVE: While mortality for complicated type B dissection has been significantly reduced with the advent of thoracic endovascular aortic repair (TEVAR), acute type A aortic dissection still carries a 25% mortality based on international registries. In this study, we simulated type A dissection by computational fluid dynamics (CFD) to determine the relationship of hemodynamic factors to dissection propagation. We also determined anatomic feasibility of TEVAR in patients with acute type A dissection by characterizing primary intimal tears using 64-multislice computerized tomography (MSCT). METHODS: CFD models of aortic dissection were constructed. Dissection propagation was simulated in single- and double-entry intimal tear conditions. Impact of pressure field distribution on tearing force was determined. On the clinical side, 17 patients with acute type A aortic dissection were investigated using 64-slice CT scans. Physical characteristics of intimal tears and potential obstacles for TEVAR were sought. RESULTS: CFD models revealed that the tearing force for dissections with a single entry tear was approximately proportional to the rate of pressure rise and the second power of dissection length. Introduction of a second tear distally along the dissection away from the primary entry tear significantly reduced tearing force. On MSCT, ascending aorta (29%) and sinotubular junction (29%) were the most frequent regions where intimal tears originated. Location of intimal tears in nearly 75% of patients was inappropriate for TEVAR, and 94% of patients did not have sufficient proximal or distal landing zone required for secure fixation. Regarding the available commercial devices, only one patient met all technical criteria for TEVAR. CONCLUSIONS: TEVAR for aortic dissection should ideally cover both entry and re-entry tears to reduce risk of propagation. Location of intimal tear, aortic valve insufficiency, and aortic diameter were major factors limiting use of TEVAR for acute type A dissection. Available stents used to treat type B dissection do not address anatomic constraints present in type A dissection in the majority of cases, such that new device development would be required.