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KMID : 1011920100110030023
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International Journal of Arrhythmia
2010 Volume.11 No. 3 p.23 ~ p.28
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Catheter ablation for tachycardia-bradycardia syndrome
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On Young-Keun
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Abstract
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Sinus node (SAN) dysfunction is frequently associated with atrial fibrillation (AF), and can lead to syncopal attacks after AF termination, a condition forming the basis of the “tachycardia-bradycardia syndrome.”Although abnormalities of SAN structure have been noted in patients with AF, there is increasing evidence of a reversible component related to SAN remodeling caused by rapid atrial tachyarrhythmias. It has been demonstrated that when AF patients show prolonged sinus pauses on AF termination, successful AF ablation is followed by a marked recovery in SAN function indices. In animal models, atrial tachyarrhythmia downregulates SAN HCN2/4 and minK subunit expression, along with the corresponding currents If and IKs. Tachycardia-induced remodeling of SAN ion channel expression, particularly for the “pacemaker” subunit If, may contribute to the clinically significant association between SAN dysfunction and supraventricular tachyarrhythmias. SAN dysfunction in AF is also associated with calcium clock malfunctioning, characterized by unresponsiveness to isoproterenol caffeine and the down-regulation of type 2 ryanodine recepter (RYR2) in SAN. Therefore sinus node dysfunction caused by atrial tachyarrhythmias could be reversed by curative ablation of AF, thus avoiding the need for pacemaker implantation. Radiofrequency cathether ablation should be an opinion of the treatment for the tachycardia-bradycardia syndrome.
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KEYWORD
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tachycardia-bradycardia syndrome, atrial fibrillation, ablation
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