RESUMO
This review is a summary of the pathophysiology of atrial fibrillation (AF) and the progress in the understanding of this arrhythmia. The following factors should be considered in the genesis and maintenance of AF. The genetic factor is involved in cases of familial AF. Predisposing structural factors: atrial dilation, structural feature that allows the development of AF. Predisposing structural factors: the role of the Bachmann's bundle and frequency gradients between the left and right atrium. Electrophysiological factors: heterogeneous refractory periods favor the fibrillatory conduction. Triggers: abnormal electrical activity (ectopic foci). Modulating factors: autonomic nervous system. Increased vagal tone shortens atrial refractory periods, creating a greater dispersion of the refractory periods and the generation of reentries in the context of triggered activity. Finally, there are three types of atrial remodeling secondary to AF: structural, contractile, electrical. They are interrelated and contribute to maintaining the AF ("AF begets AF").
Assuntos
Humanos , Fibrilação AtrialRESUMO
Los tumores primarios del corazón son poco comunes. Los más frecuentes durante la niñez son los rabdomiomas. El diagnóstico puede efectuarse desde la etapa fetal. La evolución es variada, en algunos casos no existe sintomatología y el diagnóstico representa un hallazgo ecocardiográfico, en otros se manifiesta por la presencia de soplo cardíaco, otros más se detectan asociados con esclerosis tuberosa y un pequeño grupo se manifiesta por arritmias o bajo gasto. Por lo raro de su presentación sobre todo en etapa fetal se presenta este caso.
Primary heart tumors are not very common, frequent ones during childhood are the rhabdomyomas. This diagnostic can be made since fetal life. Evolution variates, in some cases there are no symptoms and the diagnostic represents an echocardiographic finding, other cases are detected associated with tuberous sclerosis and a small group express by arrhythmias or low output. Because of the strange of this presentation this case is presented. (Arch Cardiol Mex 2004; 74:49-52).