Subject-specific factors affecting particle residence time distribution of left atrial appendage in atrial fibrillation: A computational model-based study

Soroosh Sanatkhani; Sotirios Nedios; Prahlad G Menon; Samir F Saba; Sandeep K Jain; William J Federspiel; Sanjeev G Shroff

doi:10.3389/fcvm.2023.1070498

Subject-specific factors affecting particle residence time distribution of left atrial appendage in atrial fibrillation: A computational model-based study

Front Cardiovasc Med. 2023 Mar 13:10:1070498. doi: 10.3389/fcvm.2023.1070498. eCollection 2023.

Authors

Soroosh Sanatkhani¹, Sotirios Nedios^{2

3

4}, Prahlad G Menon¹, Samir F Saba⁵, Sandeep K Jain⁵, William J Federspiel¹, Sanjeev G Shroff¹

Affiliations

¹ Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States.
² Department of Electrophysiology, Massachusetts General Hospital, Boston, MA, United States.
³ Heart Center, Department of Electrophysiology, University of Leipzig, Leipzig, Germany.
⁴ Cardiovascular Research Institute Maastricht (CARIM), Department of Cardiology, Maastricht University Medical Center, Maastricht, Netherlands.
⁵ Heart and Vascular Institute, UPMC Presbyterian, Pittsburgh, PA, United States.

Abstract

Background: Atrial fibrillation (AF) is a prevalent arrhythmia, that causes thrombus formation, ordinarily in the left atrial appendage (LAA). The conventional metric of stroke risk stratification, CHA₂DS₂-VASc score, does not account for LAA morphology or hemodynamics. We showed in our previous study that residence time distribution (RTD) of blood-borne particles in the LAA and its associated calculated variables (i.e., mean residence time, t_m , and asymptotic concentration, C _∞) have the potential to improve CHA₂DS₂-VASc score. The purpose of this research was to investigate the effects of the following potential confounding factors on LAA t_m and C _∞: (1) pulmonary vein flow waveform pulsatility, (2) non-Newtonian blood rheology and hematocrit level, and (3) length of the simulation.

Methods: Subject-Specific data including left atrial (LA) and LAA cardiac computed tomography, cardiac output (CO), heart rate, and hematocrit level were gathered from 25 AF subjects. We calculated LAA t_m and C _∞ based on series of computational fluid dynamics (CFD) analyses.

Results: Both LAA t_m and C _∞ are significantly affected by the CO, but not by temporal pattern of the inlet flow. Both LAA t_m and C _∞ increase with increasing hematocrit level and both calculated indices are higher for non-Newtonian blood rheology for a given hematocrit level. Further, at least 20,000 s of CFD simulation is needed to calculate LAA t_m and C _∞ values reliably.

Conclusions: Subject-specific LA and LAA geometries, CO, and hematocrit level are essential to quantify the subject-specific proclivity of blood cell tarrying inside LAA in terms of the RTD function.

Keywords: computational fluid dynamics; confounding variables; hematocrit; mean residence time; pulmonary vein flow; pulsatility; simulation length.

Grants and funding

This study was supported by Gerald E. McGinnis Endowed Chair Funds (SGS), American Heart Association grant [#20PRE35210594] (SS), and Leonard H. Berenfield Graduate Fellowship in Cardiovascular Bioengineering (SS).