Dataset Information

Stroke propensity is increased under atrial fibrillation hemodynamics: a simulation study.

ABSTRACT: Atrial fibrillation (AF) is the most common sustained dysfunction in heart rhythm clinically and has been identified as an independent risk factor for stroke through formation and embolization of thrombi. AF is associated with reduced cardiac output and short and irregular cardiac cycle length. Although the effect of AF on cardiac hemodynamic parameters has been reported, it remains unclear how the hemodynamic perturbations affect the potential embolization of blood clots to the brain that can cause stroke. To understand stroke propensity in AF, we performed computer simulations to describe trajectories of blood clots subject to the aortic flow conditions that represent normal heart rhythm and AF. Quantitative assessment of stroke propensity by blood clot embolism was carried out for a range of clot properties (e.g., 2-6 mm in diameter and 0-0.8 m/s ejection speed) under normal and AF flow conditions. The simulations demonstrate that the trajectory of clot is significantly affected by clot properties as well as hemodynamic waveforms which lead to significant variations in stroke propensity. The predicted maximum difference in stroke propensity in the left common carotid artery was shown to be about 60% between the normal and AF flow conditions examined. The results suggest that the reduced cardiac output and cycle length induced by AF can significantly increase the incidence of carotid embolism. The present simulations motivate further studies on patient-specific risk assessment of stroke in AF.

SUBMITTER: Choi HW

PROVIDER: S-EPMC3764003 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Stroke propensity is increased under atrial fibrillation hemodynamics: a simulation study.

Choi Hyo Won HW Navia Jose A JA Kassab Ghassan S GS

PloS one 20130905 9

Atrial fibrillation (AF) is the most common sustained dysfunction in heart rhythm clinically and has been identified as an independent risk factor for stroke through formation and embolization of thrombi. AF is associated with reduced cardiac output and short and irregular cardiac cycle length. Although the effect of AF on cardiac hemodynamic parameters has been reported, it remains unclear how the hemodynamic perturbations affect the potential embolization of blood clots to the brain that can c ...[more]

PMID: 24039957

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Project description:Atrial fibrillation (AF) patients are at high risk of stroke, with the left atrial appendage (LAA) found to be the most common site of clot formation. Presence of left atrial (LA) fibrosis has also been associated with higher stroke risk. However, the mechanisms for increased stroke risk in patients with atrial fibrotic remodeling are poorly understood. We sought to explore these mechanisms using fluid dynamic analysis and to test the hypothesis that the presence of LA fibrosis leads to aberrant hemodynamics in the LA, contributing to increased stroke risk in AF patients. We retrospectively collected late-gadolinium-enhanced MRI (LGE-MRI) images of eight AF patients (four persistent and four paroxysmal) and reconstructed their 3D LA surfaces. Personalized computational fluid dynamic simulations were performed, and hemodynamics at the LA wall were quantified by wall shear stress (WSS, friction of blood), oscillatory shear index (OSI, temporal directional change of WSS), endothelial cell activation potential (ECAP, ratio of OSI and WSS), and relative residence time (RRT, residence time of blood near the LA wall). For each case, these hemodynamic metrics were compared between fibrotic and non-fibrotic portions of the wall. Our results showed that WSS was lower, and OSI, ECAP, and RRT was higher in the fibrotic region as compared to the non-fibrotic region, with ECAP (p = 0.001) and RRT (p = 0.002) having significant differences. Case-wise analysis showed that these differences in hemodynamics were statistically significant for seven cases. Furthermore, patients with higher fibrotic burden were exposed to larger regions of high ECAP, which represents regions of low WSS and high OSI. Consistently, high ECAP in the vicinity of the fibrotic wall suggest that local blood flow was slow and oscillating that represents aberrant hemodynamic conditions, thus enabling prothrombotic conditions for circulating blood. AF patients with high LA fibrotic burden had more prothrombotic regions, providing more sites for potential clot formation, thus increasing their risk of stroke.

Dataset Information

Stroke propensity is increased under atrial fibrillation hemodynamics: a simulation study.

Publications

Stroke propensity is increased under atrial fibrillation hemodynamics: a simulation study.

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