Understanding the role of the left atrial appendage on the flow in the atrium

Area of Science:

• Cardiovascular Science
• Biomedical Engineering
• Medical Physics

Background:

• Left atrial appendage (LAA) occlusion is a therapeutic option for atrial fibrillation (AF) patients at high risk of stroke and bleeding.
• The precise physiological role of the LAA remains incompletely understood, necessitating further investigation into its impact on cardiac function.

Purpose of the Study:

• To investigate the hemodynamic effects of LAA exclusion in patients with atrial fibrillation.
• To assess the changes in left atrial (LA) flow dynamics following LAA exclusion procedures.

Main Methods:

• Computational fluid dynamics (CFD) simulations were employed to analyze blood flow in the LA of nine AF patients.
• Simulations were conducted before and after LAA exclusion, examining parameters like LA velocities, Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), Relative Residence Time (RRT), and LA pressure.

Main Results:

• LAA exclusion led to a significant decrease in TAWSS (1.82 ± 1.85 Pa to 1.27 ± 0.96 Pa, p < 0.05) and a reduction in low-magnitude velocities.
• Conversely, a slight increase was observed in OSI (0.16 ± 0.10 to 0.17 ± 0.10, p < 0.05), RRT (1.87 ± 1.84 Pa⁻¹ to 2.11 ± 1.78 Pa⁻¹, p < 0.05), and LA pressure (-19.2 ± 6.8 mmHg to -15.3 ± 8.3 mmHg, p < 0.05).

Conclusions:

• LAA exclusion is associated with measurable alterations in left atrial hemodynamics.
• Further research is warranted to fully understand the clinical significance of these observed hemodynamic changes in AF patients.