Aortic stiffening after thoracic aortic stent grafting: A multi-patient specific computational study

Area of Science:

• Cardiovascular Engineering
• Biomedical Simulation
• Medical Device Analysis

Background:

• Descending Thoracic Aortic Aneurysm (DTAA) treatments modify aortic anatomy and biomechanics, leading to complex, unexplored interactions.
• Current surgical and endovascular repair methods can cause anomalous wave reflections and cardiac remodeling.
• Predicting long-term outcomes of DTAA repair is challenging due to these intricate dynamics.

Purpose of the Study:

• To investigate the interplay between altered aortic geometry and material stiffness post-DTAA repair.
• To evaluate the impact of surgical interventions on cardiovascular hemodynamics using computational modeling.
• To develop cost-effective 0D-1D fluid-structure interaction (FSI) models for DTAA repair analysis.

Main Methods:

• Integrated 0D left heart models with 1D systemic circulation models in a C++ finite element library.
• Developed patient-specific 1D-FSI models from CT angiography data for 11 DTAA patients (open surgery and TEVAR).
• Simulated preoperative and postoperative hemodynamics, comparing pressure, PV loops, and PWV.

Main Results:

• Implant presence can increase ascending aorta pressure due to reflected waves; TEVAR cases showed higher PWV.
• Postoperative changes in geometry and stiffness significantly altered cardiac PV loops.
• Descending aortic elongation was found to independently compensate for material stiffness, correlating with reduced post-operative pressure elevation.

Conclusions:

• Combined analysis of stiffness and geometric changes is crucial for understanding DTAA repair outcomes.
• Aortic geometry modifications can mitigate the negative effects of increased arterial stiffness post-surgery.
• These findings can inform strategies for improving the long-term efficacy and predictability of DTAA repair.