Fluid-structure interaction in aortic cross-clamping: implications for vessel injury

Area of Science:

• Biomedical Engineering
• Cardiovascular Surgery
• Materials Science

Background:

• Vascular cross-clamping is a common surgical procedure for cardiovascular interventions like bypass and valve repair.
• Previous research indicates that arterial clamping can lead to vessel wall damage.
• The specific impact of different surgical clamp designs on arterial tissue mechanics remains incompletely understood.

Purpose of the Study:

• To investigate the biomechanical effects of commonly used surgical clamps on the arterial wall.
• To analyze how clamp design influences stress distribution and magnitude within the vessel wall.
• To evaluate the mechanical loading on the endothelium during vascular cross-clamping.

Main Methods:

• Development of 3D models of the aorta and surgical clamps using Computer-Aided Design (CAD).
• Finite Element Analysis (FEA) was employed to simulate the mechanical behavior of the vessel wall as a non-linear anisotropic material.
• Fully coupled two-way solid-fluid interaction models were created to simulate pulsatile blood flow and clamp application via a displacement time function.

Main Results:

• Clamp design significantly alters stress distribution in the vessel wall; protrusion clamps increased Von Mises stress by ~60% and compressive stress by >200%.
• The protrusion clamp resulted in significantly higher Von Mises stress on the lumen (endothelium) side (ratio ~2:1) compared to the outer wall, unlike plate-like clamps (ratio ~1.3:1).
• Flow reversal, vibrations, and wall shear stress oscillations were observed prior to complete vessel occlusion, indicating transient mechanical disturbances.

Conclusions:

• The design of surgical clamps critically impacts mechanical stresses on the arterial wall, particularly compressive stress.
• Protrusion clamp designs exacerbate stress on the endothelium, posing a risk of vascular injury.
• These findings offer valuable insights for optimizing surgical clamp design and understanding endothelial injury mechanisms during cardiovascular procedures.