Biomechanical and Microstructural Properties of Ascending Aortic Aneurysms

BIOMECHANICAL AND MICROSTRUCTURAL PROPERTIES OF THE AORTIC WALL: A Pilot Study in Patients Undergoing Surgery for Ascending Aortic Aneurysms

An aortic aneurysm (thoracic or abdominal) is a permanent dilatation of the aorta caused by weakening in the arterial wall. The feared complication is aortic rupture or dissection, leading to potentially lethal aortic bleeding and associated with mortality rates up to 95%. The current diagnosis criteria do not suffice, therefore the goal of this study is the development of an improved biomechanics-based and microstructural-based diagnostic tool.

An aortic aneurysm (thoracic or abdominal) is a permanent dilatation of the aorta caused by weakening in the arterial wall. The feared complication is aortic rupture or dissection, leading to potentially lethal aortic bleeding and associated with mortality rates up to 95%. Diagnosis of the aneurysm and especially its risk of rupture or dissection is highly challenging. If the aneurysm diameter and/or growth rate exceed a specific threshold (respectively 55 mm and 1 cm/year), a highly invasive and dangerous surgery is performed. However, several studies have shown no correlation between the maximum transverse diameter and the risk of rupture or dissection. Since aneurysm rupture is associated with multiple aortic tissue properties, both biomechanics-based and microstructurally-based criteria can be a promising alternative.

The overall goal of this trial is a biomechanical and microstructural analysis of aneurysms to improve the diagnostic criterion for aneurysm rupture risk. Within this goal, two scientific objectives can be distinguished. Firstly, a highly unique dataset with patient data allowing the development of an improved diagnostic tool will be created. This dataset will contain an abundance of relevant parameters such as patient characteristics, geometry, material properties and biomechanical and microstructural characteristics. The biomechanical and microstructural data will be obtained by the analysis of resected aneurysmal tissue and by dynamic imaging (4D CT). 4D CT scans are a series of ECG-gated scans that are taken at specified intervals in the cardiac circle. The second objective is to create a personalized diagnostic tool. An aneurysm rupture risk criteria based on geometry as well as biomechanical and microstructural properties is expected to be significantly more reliable than the current criteria. More specifically, a correlation between patient characteristics that can be measured non-invasively and the aneurysm rupture risk is searched for.

Inclusion Criteria:

• Patients suffering from thoracic aortic aneurysms (ATAA), asymptomatic or symptomatic.
• Patients with ruptured ATAA undergoing an emergency surgery.
• Signed informed consent.

Exclusion Criteria:

• Patients with ruptured ATAA due to trauma.
• The presence of any aneurysm feature that will prevent the collection of tissue samples suitable for the biomechanical and microstructural studies.