Abstract
Background: Although atrial fibrillation (AF), a common arrhythmia, frequently presents in patients with underlying valvular disease, its hemodynamic contributions are not fully understood. The present work aimed to computationally study how physical conditions imposed by pathologic valvular anatomy act on AF hemodynamics.Methods: We simulated AF with different severity grades of left-sided valvular diseases and compared the cardiovascular effects that they exert during AF, compared to lone AF. The fluid dynamics model used here has been recently validated for lone AF and relies on a lumped parameterization of the four heart chambers, together with the systemic and pulmonary circulation. The AF modelling involves: (i) irregular, uncorrelated and faster heart rate; (ii) atrial contractility dysfunction. Three different grades of severity (mild, moderate, severe) were analyzed for each of the four valvulopathies (AS, aortic stenosis, MS, mitral stenosis, AR, aortic regurgitation, MR, mitral regurgitation), by varying–through the valve opening angle–the valve area.Results: Regurgitation was hemodynamically more relevant than stenosis, as the latter led to inefficient cardiac flow, while the former introduced more drastic fluid dynamics variation. Moreover, mitral valvulopathies were more significant than aortic ones. In case of aortic valve diseases, proper mitral functioning damps out changes at atrial and pulmonary levels. In the case of mitral valvulopathy, the mitral valve lost its regulating capability, thus hemodynamic variations almost equally affected regions upstream and downstream of the valve. In particular, the present study revealed that both mitral and aortic regurgitation strongly affect hemodynamics, followed by mitral stenosis, while aortic stenosis has the least impact among the analyzed valvular diseases.Discussion: The proposed approach can provide new mechanistic insights as to which valvular pathologies merit more aggressive treatment of AF. Present findings, if clinically confirmed, hold the potential to impact AF management (e.g., adoption of a rhythm control strategy) in specific valvular diseases.
Highlights
Atrial fibrillation (AF) is the most prevalent sustained tachyarrhythmia, currently affecting up to 2% of the general population (Andrade et al, 2014), producing symptoms and decreasing cardiac performance (Fuster et al, 2006)
To double check the validity of this procedure, besides the hemodynamic parameters introduced at the beginning of this section, we evaluated as post-processing parameters the regurgitant volumes, RV [ml/beat], and the mean pressure gradients, MPG [mmHg], to evaluate the indexes recommended by current clinical guidelines to grade regurgitation and stenosis severity (Baumgartner et al, 2009; Lancellotti et al, 2010a; Lancellotti et al, 2010b)
The cardiovascular hemodynamic outcomes for stenosis and regurgitation are given in Tables 1 and 2, respectively
Summary
Atrial fibrillation (AF) is the most prevalent sustained tachyarrhythmia, currently affecting up to 2% of the general population (Andrade et al, 2014), producing symptoms (such as chest pain, palpitations, reduced exercise tolerance, shortness of breath) and decreasing cardiac performance (Fuster et al, 2006). Current literature primarily refers to AF patients in general, without focusing on the concomitant effect of underlying valvular disease present in a relevant subgroup of AF patients (Darby & DiMarco, 2012; Vora, 2006). Atrial fibrillation (AF), a common arrhythmia, frequently presents in patients with underlying valvular disease, its hemodynamic contributions are not fully understood. In case of aortic valve diseases, proper mitral functioning damps out changes at atrial and pulmonary levels. In the case of mitral valvulopathy, the mitral valve lost its regulating capability, hemodynamic variations almost affected regions upstream and downstream of the valve. The present study revealed that both mitral and aortic regurgitation strongly affect hemodynamics, followed by mitral stenosis, while aortic stenosis has the least impact among the analyzed valvular diseases. If clinically confirmed, hold the potential to impact AF management (e.g., adoption of a rhythm control strategy) in specific valvular diseases
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