  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. 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.
Three different grades of severity (mild, moderate, severe) were analyzed for
each of the four valvulopathies (aortic stenosis, mitral stenosis, aortic
regurgitation, mitral regurgitation). 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. 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. 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.
