Figure 2. Main classification of the acute TBAD primary entry tear positions. Inner (concave) (A ) primary entry tears (IT) occur at the inner circumference of the distal aortic arch and are unopposed to retrograde sequelae in the aortic arch and ascending aorta. Outer (convex) (B ) primary entry tears (OT) occur at the outer circumference of the distal aortic arch and are opposed to retrograde sequelae by the left subclavian artery. Adapted and reproduced from Loewe et. al (27) with permission from Elsevier.