Atrial fibrillation is a very common cardiac arrhythmia that can degenerate into deadly cardiovascular events. Some of its possible complications are heart failure and stroke, given that as the auricles do not contract properly, facilitating the formation of blood clots on inside. Therefore, patients with atrial fibrillation are at high risk of developing blood clots which are associated with a high rate of both mortality and disability.

The left atrial appendage is a complex and heterogeneous heart structure that protrudes from the left atrium and in patients with atrial fibrillation it is where 90% of thromboembolisms form.  However, the role of this cardiac anatomical structure in the formation of blood clots is not sufficiently well known.

Through computational analysis, the results of a recent study published in advance online in theInternational Journal for Numerical Methods in Biomedical Engineering could contribute to better understanding this structure and help clinical decision-making for the prevention of complications in patients with atrial fibrillation.

This main goal of work, led by Òscar Camara, with Guadalupe García-Isla, a student of the master’s degree in “Computational Biomedical Engineering” at UPF, and first author, with the participation of other members of the Department of Information and Communication Technologies (DTIC) at UPF, along with experts of Hospital Clínic of Barcelona and the University Extremadura and researchers from centres in Belgium, Chile and France, was to perform a sensitivity analysis to identify the most important morphological parameters in atrial blood flow dynamics, in the left atrium and in the left atrial appendage.

The researchers performed blood fluid simulations on atrial models according to different individual variables: size of the mitral valve and pulmonary veins, morphology of the left appendage and left atrial volume. The computational analysis confirmed that there is a relationship between the inlet to the left appendage (ostium) and the formation of thromboembolisms. More specifically, they found that the bigger this orifice, the slower the blood flow and increased clot formation. In addition, the authors of the study have found that the configuration of the pulmonary veins has a critical influence on the patterns of blood flow in the left appendage.

These findings contribute to a better understanding of the structure of the left appendage and could support clinical decisions for the prevention of complications in patients with atrial fibrillation. Future research in this line include the use of simulation tools and visual interfaces (via web, virtual reality) to optimize the implementation of occlusion devices in the left appendage.

This research has been carried out thanks to the financial aid obtained from the Spanish Ministry of Economy, Industry and Competitiveness and from the Marató de TV3 fundraising event. The first author, Guadalupe García-Isla, conducted this research as part of her master’s degree thesis on “Computational Biomedical Engineering” at UPF.

Reference work:

Guadalupe García-Isla, Andy L. Olivares, Etelvino Silva, Marta Nuñez-García, Constantine Butakoff, Damian Sánchez-Quintana, Hernán G. Morales, Xavier Freixa, Jérôme Noailly, Tom De Potter, Oscar Camara (2018), “Sensitivity analysis of geometrical parameters to study haemodynamics and thrombus formation in the left atrial appendage”, International Journal for Numerical Methods in Biomedical Engineering, https://doi.org/10.1002/cnm.3100.