[Heart rhythm disorders of supraventricular origin in children].

An analysis and updating is made, of the main supraventricular heart rhythm disturbances encountered in children, excepting paroxysmal supraventricular tachycardia, which remains the major clinical entity in this field, but was presented by the same authors in a previous issue of this journal. A review is made of vasovagal syncope, of sinusal tachy- and bradycardia, of atrial extrasystolic arrhythmia, of the sinus node disease, of atrial flutter, and of atrial fibrillation. On the basis of modern studies in the field of electrophysiology, including endocavitary electrophysiology, the major mechanisms are presented, involved in triggering all types of heart tachyarrhythmias, namely: abnormal automatism (automatic ectopic focuses), the "re-entry mechanism" and the "triggered dysrhythmia". Particular attention is given to extrasystolic arrhythmias of atrial origin, and to the sinus node disease, of which the first is important because of its frequency while the second one is remarkable because of the considerable mass of new data that have been published in the literature. A review is made of etiologic aspects, as well as clinical, electrocardiographic, and therapeutical data related to heart rhythm disturbances of supraventricular origin, as well as a series of considerations in relation to evolution and prognosis. The authors stress certain difficulties of diagnosis, especially with electrocardiograms, as is the case, for instance, with blocked bigeminal atrial extrasystoles, with the sinus node disease, etc. In the final part of the paper two more rarely encountered disturbances are presented; atrial fibrillation and atrial flutter. These two entities are also defined on the basis of clinical and electrocardiographic data, and their analysis is also made from the viewpoint of their etiology. A discussion is made concerning the therapeutic aspects, and their evolution and prognosis.