Aortic dissection is a local tear in the aortic wall that leads to a parallel blood flow within the wall, a so-called “false lumen”. The disease is asymptomatic and may result in sudden death if the degraded aortic wall ruptures. Recently, we used high resolution synchrotron imaging to demonstrate that small side branches play an important role in the initiation and propagation of aortic dissections in mice. These findings were confirmed in an advanced computational biomechanical model. Our current research proposal aims to expand on these findings via two parallel approaches. On the one hand, we aim to deepen our knowledge of the importance of side branches in the initiation of cardiovascular disease in mice. To this end we will set up more sophisticated synchrotron experiments that will allow us to visualize the micro-structure of the aorta while it is being pressurized. On the other hand, we aim to verify whether side branches play an equally important role in human disease. More specifically, we hypothesize that outflow from minor side branches that sprout from the false lumen is an underestimated factor in the progression and prognosis of aortic dissection. To verify this hypothesis, we will analyze n=96 clinically available CT scans, as well as biomechanical models based on (some of) these scans. We also plan to visualize human aortic tissue (both straight and branching segments) with high resolution synchrotron imaging.