Differential propensity of dissection along the aorta

Area of Science:

• Biomedical Engineering
• Computational Mechanics
• Cardiovascular Research

Background:

• Aortic dissections are life-threatening conditions involving aortic wall delamination.
• Previous studies identified two distinct tearing modes (stepwise and sudden) in aortic dissections.
• A detailed microstructural understanding of these tearing modes is lacking.

Purpose of the Study:

• To develop a computational model explaining the microstructural mechanisms behind aortic dissection tearing modes.
• To investigate the relationship between local geometry, material properties, and tearing pressure.
• To elucidate the role of radial struts in aortic wall delamination.

Main Methods:

• Implementation of a phase-field finite-element model of the aortic wall.
• Integration of two-photon imaging data to inform the model.
• Analysis of correlative relations between pressure, geometry, and material properties.

Main Results:

• The model identified a correlation: tearing pressure squared is directly proportional to tissue stiffness and critical tearing energy, and inversely proportional to the square root of the torn area.
• This correlation explains the sudden tearing mode observed in the thoracic aorta.
• Microscopy revealed more abundant radial struts in the abdominal aorta, correlating with progressive tearing and suggesting their role in increasing tearing pressure.

Conclusions:

• Phase-field models provide insights into intramural delaminations driving aortic dissections.
• Radial struts mechanically influence tearing pressure by fluid confinement and increased tissue stiffness.
• The study elucidates the distinct mechanisms underlying progressive and sudden aortic dissection tearing modes.