Tachyatrhythmias In Infants And Children Under Age Of 10 Years:

Saad Ibrahim Abd El Wahab

Normal rhythmic cardiac contraction is initiated by spontaneous depolarization of the sinoatrial node• This depolarization generates an impulse that spreads sequentially through the artrial wall and specialized internodal tracts to the atrioventricular node, andthen to the his bundle and its branches to reach the purkinje network and to excite the ventricular muscle.Tachyarrhythmias are defined as the rates which are more rapid than normal, regular or irregular, arising from the sinus Dode, the atria, the atrioventricular junction or the ventricles (Moss and Adames, 1968).When an ectopic focus generates an impulse faster than the sinns discharge rate, it assumes control of the heart and ectopic tachycardia results. Prom an electrophysiologic standpoint there is evidence for both reentry and automatic ectopic focus mechanisms to account for the pathologic tachycardias (Courtney, 1980). It is traditional to divide the tachyarrhythmias according to whether the pacemaker (reentrant or automatic ectopic) is above or below the His bundle bifuraction supraventricular and ventricular. Such categorization is useful because of etiologic and therapeutic differences.