[Remodeling in atrial fibrillation].
BACKGROUND
Atrial fibrillation is associated with alterations in atrial electrophysiology that facilitate the initiation and persistence of the arrhythmia. This process was termed electrical remodeling in atrial fibrillation. The underlying cellular and molecular mechanisms have intensively been investigated over the past few years in patients with atrial fibrillation and in different experimental models. The results, that have substantially improved the understanding of the pathophysiology of atrial fibrillation, are reviewed.
On the cellular level, atrial fibrillation leads to a strong shortening and an impaired rate adaptation of the action potential as well as to changes in action potential morphology. Atrial fibrillation is associated with an altered gene expression of the L-type calcium channel (ICa,L) and of potassium channels (Ito, IK1, IKACh). The molecular mechanisms of intraatrial conduction slowing are less well understood, changes in the expression or distribution of gap junction proteins or a decrease of the fast sodium inward channel (INa) have been reported in some studies. A trigger of initiation for electrical remodeling is an overload of the cytoplasm with Ca2+ and a consecutive decrease of the systolic calcium gradient, furthermore changes in calcium-handling proteins are detectable in atrial fibrillation.


CONCLUSIONS
These changes in the cellular and molecular milieu importantly determine the clinical course and the efficacy of therapeutical interventions in atrial fibrillation. The clinical relevance and potential new therapeutic approaches are discussed in the last part.
Bosch
Ralph F
RF
Abteilung Kardiologie, Medizinische Klinik und Poliklinik, Eberhard-Karls-Universität Tübingen. ralph.bosch@uni-tuebingen.de
Seipel
Ludger
L
Kühlkamp
Volker
V
D000818:Animals; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000235:genetics / Q000503:physiopathology*; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000502:physiology; D017630:Connexins / Q000235:genetics / Q000502:physiology; D004562:Electrocardiography; D015870:Gene Expression / Q000502:physiology; D006325:Heart Atria / Q000503:physiopathology*; D006801:Humans; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology
D020746:Calcium Channels, L-Type; D017630:Connexins; D015221:Potassium Channels