Related Experiment Video
Updated: Jul 4, 2026
Estimating Bilateral Atrial Function by Cardiovascular Magnetic Resonance Feature Tracking in Patients with Paroxysmal Atrial Fibrillation
Published on: July 20, 2022
Characterizing left atrial appendage functions in sinus rhythm and atrial fibrillation using computational models
1Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. Zhanglucy@rpi.edu
Insights
The left atrial appendage contributes to thrombus formation in atrial fibrillation due to poor blood flow and stagnation. Mathematical models reveal its non-functional role in sinus rhythm, highlighting risks in abnormal heart rhythms.
Area of Science:
- Cardiovascular physiology
- Medical fluid dynamics
- Computational biology
Background:
- The left atrial appendage (LAA) is implicated in thrombus formation in atrial fibrillation (AF).
- Understanding LAA function in different heart rhythms is crucial for preventing thromboembolism.
Purpose of the Study:
- To characterize the functional role of the LAA in sinus rhythm and AF.
- To investigate the impact of blood flow dynamics within the LAA and left atrium.
Main Methods:
- Development and application of mathematical models.
- Simulation of blood flow in the left atrium and LAA.
- Analysis of transmitral and appendage filling/emptying velocities.
Main Results:
- LAA demonstrates minimal functional impact on transmitral velocities during sinus rhythm.
- Absence of atrial contraction in AF leads to missing A-wave velocities.
- In AF, persistent high-strength vortices contribute to blood stagnation and ineffective emptying.
Conclusions:
- The LAA is functionally passive during normal sinus rhythm.
- Blood stagnation and thrombus formation in AF are linked to impaired LAA emptying and vortex dynamics.
- Mathematical modeling provides insights into LAA function and its role in AF pathophysiology.
Abstract:
Clinical studies show that the left atrial appendage, a blind-ended structure that is attached to the left atrium, may be the cause of 90% of atrial thrombi in atrial fibrillation (abnormal heart rhythm), and it is much reduced in sinus (normal) rhythm. In this paper, the effects of blood flows in left atrium and left atrial appendage are studied to help characterize the atrial appendage functions in sinus rhythm and atrial fibrillation using mathematical models. Our results show that the left atrial appendage is not functional in sinus rhythm because the atrial transmitral velocities remained almost identical for atria with and without appendage, which agrees with the current clinical observations. However, in atrial fibrillation, a proper atrial contraction is absent, which causes the second emptying velocity (A-wave) to be missing in both transmitral velocity and appendage filling/emptying velocity. Without the proper emptying of the blood, vortices generated in the chamber remain high strengths and with longer durations. They induce ineffective emptying of the blood in the atrium and appendage, which then lead to blood stagnation and subsequent thrombus formation.
