Inverse Correlation Between Left Atrial Appendage Function and CHA2DS2-VASc Score in Patients with Atrial Flutter

Integrating soft robotics and computational models to study left atrial hemodynamics and device testing in sinus rhythm and atrial fibrillation

Atrial fibrillation (AF) poses significant clinical challenges due to the complex and variable geometry of the left atrial appendage (LAA), whose structure complicates the development of personalized interventions like LAA occlusion (LAAO) for stroke prevention Current reliance on animal models and cadavers for the assessment of left atrium (LA) and LAA to study AF-related disease and interventions raises reproducibility concerns, necessitating the development of high fidelity, physiologically relevant tools. To address this, we present a multimodal framework combining a soft robotic benchtop simulator, a lumped parameter model (LPM), and finite element analysis (FEA) to replicate LA function in sinus rhythm, atrial flutter, and AF. The system integrates 3D-printed, patient-specific LA geometries with soft robotic actuators to reproduce realistic wall motion and hemodynamics. A compact, magnetic resonance imaging (MRI)-compatible flow loop, driven by a soft robotic left ventricle (LV), eliminates bulky and non-physiological pulsatile pumps, allowing precise flow measurements and LAAO device testing under clinically relevant conditions. Complementary LPM and FEA models provide mechanistic insights, quantifying systemic hemodynamic changes and LA wall stress during disease and interventions. The models effectively replicate the clinical markers of atrial dysfunction and arrhythmia disorders, and their physiological accuracy is demonstrated through validation against human imaging and porcine models. The soft robotic LV's ability to drive the mock flow loop is validated in a hybrid synthetic-biological configuration within a swine circulatory system, where the soft robotic ventricle replaces native ventricular contraction to sustain systemic circulation. This scalable and versatile framework integrates experimental and computational techniques to advance cardiovascular biomechanics, supporting device development, clinical research/training, and personalized AF treatment to improve patient outcomes.

Assessment of left atrial appendage function by echocardiography

The left atrial appendage (LAA) is considered not only to be the most frequent site of thrombus formation, but also to play a pivotal role in maintaining normal cardiac function. Transesophageal echocardiography (TEE) is widely used to assess LAA function. The LAA flow velocity has been used as a surrogate for LAA function, and it varies with multiple interrelated factors including age, hemodynamics, type of arrhythmia, and antiarrhythmic interventions. Relatively great importance of LAA function is involved with intraatrial thrombus formation and subsequent thromboembolism, and thus, understanding of characteristics and behaviors of the LAA under various clinical conditions may help determine strategies against atrial thrombosis. Also, techniques other than TEE-derived Doppler to assess LAA function, such as tissue Doppler imaging, have been proposed. In this review, we introduce clinical and echocardiographic correlates of LAA function, the LAA flow velocity in particular, its significance, and how to interpret functional patterns of the LAA each relevant to specific clinical settings.

Impact of left atrial appendage location on risk of thrombus formation in patients with atrial fibrillation

Most strokes in patients with atrial fibrillation (AF) are thought to arise from thrombus formation in the left atrial appendage (LAA). Assessing the hemodynamics in LAA and left atrium (LA) may provide some insights in the evaluation of the risk of thrombus formation. This study aims to find out the impact of different LAA locations with respect of LA on the risk of thrombus formation within LAA in patients with AF. Three different LAA locations at LA were modeled and a fully coupled fluid-structure interaction analysis was performed. A discrete phase method was used for particle residence analysis to evaluate risk of the thrombus formation. The results showed that LAA positions on the LA affected the LAA flow velocity distribution, passive contraction ability, and particle residence. In particular, the left pulmonary veins (PVs) had a greater influence on the LAA hemodynamics than the right PVs. The LAA had the lowest contractibility when it was located between left superior and left inferior PVs, and in this case, a larger number of particles were resided, which indicated a higher risk of thrombus formation. The present work provides a quantitative way to evaluate the risk of thrombus formation within LAA in patients with AF.