Delise P
Divisione di Cardiologia, Ospedale Umberto I, Mestre-Venezia.
Cardiologia. 1991 Aug;36(8 Suppl):11-5.
Both supraventricular and ventricular arrhythmias are generated by one of the following 2 mechanisms: increased automaticity and reentry. In this paper we will refer about the mechanisms of the commonest atrial tachyarrhythmias. Atrial parasystole: it is determined by an automatic focus protected by entrance block. In some cases the focus is only partially protected owing to a partial block or to the electrotonic influence of the sinus rhythm. Atrial tachycardia: it can be due both to increased automaticity and to reentry. Atrial flutter: it is generated by a counterclockwise macroreentry localized in the right atrium. The left atrium is passively activated. A critical delay of the circuit is present near the ostium of the coronary sinus. The lesion of this area by surgery or catheter ablation can interrupt and prevent the arrhythmia. Atrial fibrillation: it is generated by multiple wavelets which continuously change site and direction. The functional multiple reentry is made possible by dispersion of atrial refractoriness and by the existence of areas having delayed conduction. It is noteworthy that the same arrhythmia and the same atrial electrophysiologic alterations are present in many clinical conditions having very different anatomic backgrounds: subjects with no evident heart disease and normal atria, subjects with large atria, subjects with an anomalous pathway. These data suggest that some important informations are probably lacking about the genesis of this arrhythmia.
自律性增加和折返。在本文中,我们将探讨最常见的房性快速性心律失常的机制。房性并行心律:它由受传入阻滞保护的自律性病灶决定。在某些情况下,由于部分阻滞或窦性心律的电紧张影响,该病灶仅得到部分保护。房性心动过速:它可由自律性增加和折返引起。心房扑动:它由位于右心房的逆时针大折返产生。左心房被被动激活。在冠状窦口附近存在关键的折返延迟。通过手术或导管消融破坏该区域可中断并预防心律失常。心房颤动:它由多个小波连续改变位置和方向产生。心房不应期的离散和存在传导延迟的区域使得功能性多折返成为可能。值得注意的是,在许多具有非常不同解剖背景的临床情况下,存在相同的心律失常和相同的心房电生理改变:无明显心脏病且心房正常的受试者、心房增大的受试者、存在异常通路的受试者。这些数据表明,关于这种心律失常的发生机制可能缺乏一些重要信息。