Influence of tear configuration on false and true lumen haemodynamics in type B aortic dissection

The management and follow-up of chronic type B aortic dissections continues being a clinical challenge. Patients with chronic type B dissection have high mid/long term mortality mainly due to progressive aortic dilatation and subsequent rupture. To predict further dilatation, guidelines suggest follow-up of the total aortic diameter. However, dilatation is triggered by haemodynamic parameters (intra-luminal pressure and flow conditions/wall shear stresses), and geometric factors such as the communication between false (FL) and true lumen (TL). The aim of this study is to assess whether TL and FL haemodynamics and its determinants (such as the tear size, location and number) will allow us to define risk markers of further aortic enlargement. For this, we performed in-silico studies on idealized dissected aortic geometries. A type B aortic dissection was created in which FL has double the diameter of TL. Three different circular tear configurations are studied: only a 10 mm proximal tear, and a 10 mm proximal tear with either a 4 mm or a 10 mm distal tear. Resulting flow volume, pressure, and wall shear stress (WSS) profiles of TL and FL were analyzed. Preliminary results show that the presence of an adequate outflow in the distal tear is associated with an important increase in diastolic pressure and wall stress and diastolic retrograde flow, putting FL at high risk for dilatation. We have constructed a model of a type B dissection which allows studying dissected anatomic configurations and their resulting haemodynamics. It is expected that in-silico models will show the influence of tear configuration, thus providing ways for a better understanding of the haemodynamic conditions, as observed in clinical practice, and related evolution in patients with a chronic aortic dissection.