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Updated: Jun 12, 2026
The WATCHMAN Left Atrial Appendage Closure Device for Atrial Fibrillation
Published on: February 28, 2012
Correct Closure of the Left Atrial Appendage Reduces Stagnant Blood Flow and the Risk of Thrombus Formation: A
Min Jae Cha1, Don-Gwan An2,3, Minsoo Kang2,3
1Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
Insights
Correctly occluding the left atrial appendage (LAA) significantly reduces blood stasis and thrombus formation in patients with atrial fibrillation (AF). This procedural optimization aims to maximize clinical benefits by improving intracardiac blood flow dynamics.
Area of Science:
- Cardiovascular Imaging and Hemodynamics
- Biomedical Engineering and Fluid Dynamics
Background:
- Atrial fibrillation (AF) poses a significant risk for thromboembolic events, often necessitating left atrial appendage (LAA) occlusion.
- Understanding the impact of LAA occlusion on intra-atrial blood flow is crucial for optimizing procedural outcomes and preventing thrombus formation.
Observation:
- Four-dimensional (4D) flow MRI and 3D-printed left atrium (LA) phantoms were utilized to visualize and quantify blood flow dynamics.
- Simulated pulmonary venous flow was introduced into pre-occlusion, correctly occluded, and incorrectly occluded LA models.
Findings:
- Correct LAA occlusion markedly decreased blood stasis volume and the ratio of stasis volume to total LA volume compared to pre-occlusion and incorrect occlusion models.
- Surface-and-time-averaged wall shear stress (WSS) and endothelial cell activation potential (ECAP), indicators of thrombogenicity, were lowest in the correctly occluded LAA model.
Implications:
- These findings highlight the importance of accurate LAA occlusion in mitigating thrombogenicity and improving hemodynamic conditions in AF patients.
- Achieving optimal LAA occlusion represents a key procedural goal for enhancing clinical efficacy and patient outcomes in AF management.
Objective:
The study was conducted to investigate the effect of correct occlusion of the left atrial appendage (LAA) on intracardiac blood flow and thrombus formation in patients with atrial fibrillation (AF) using four-dimensional (4D) flow magnetic resonance imaging (MRI) and three-dimensional (3D)-printed phantoms.
Materials And Methods:
Three life-sized 3D-printed left atrium (LA) phantoms, including a pre-occlusion (i.e., before the occlusion procedure) model and correctly and incorrectly occluded post-procedural models, were constructed based on cardiac computed tomography images from an 86-year-old male with long-standing persistent AF. A custom-made closed-loop flow circuit was set up, and pulsatile simulated pulmonary venous flow was delivered by a pump. 4D flow MRI was performed using a 3T scanner, and the images were analyzed using MATLAB-based software (R2020b; Mathworks). Flow metrics associated with blood stasis and thrombogenicity, such as the volume of stasis defined by the velocity threshold (|V̅| < 3 cm/s), surface-and-time-averaged wall shear stress (WSS), and endothelial cell activation potential (ECAP), were analyzed and compared among the three LA phantom models.
Results:
Different spatial distributions, orientations, and magnitudes of LA flow were directly visualized within the three LA phantoms using 4D flow MRI. The time-averaged volume and its ratio to the corresponding entire volume of LA flow stasis were consistently reduced in the correctly occluded model (70.82 mL and 39.0%, respectively), followed by the incorrectly occluded (73.17 mL and 39.0%, respectively) and pre-occlusion (79.11 mL and 39.7%, respectively) models. The surface-and-time-averaged WSS and ECAP were also lowest in the correctly occluded model (0.048 Pa and 4.004 Pa-1 , respectively), followed by the incorrectly occluded (0.059 Pa and 4.792 Pa-1 , respectively) and pre-occlusion (0.072 Pa and 5.861 Pa-1 , respectively) models.
Conclusion:
These findings suggest that a correctly occluded LAA leads to the greatest reduction in LA flow stasis and thrombogenicity, presenting a tentative procedural goal to maximize clinical benefits in patients with AF.
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