INCESSANT TACHYCARDIAS

Incessant tachycardias are some of the rarer forms of normal QRS tachy cardias. They are usually diagnosed in infancy or childhood and often present with heart failure secondary to left ventricular dysfunction. Permanent junctional reciprocating tachycardia is a rare type of ortho dromic atrioventricular re-entry. Control with drugs is possible but b est long-term results are achieved with radiofrequency ablation. Conge nital His bundle tachycardia is an automatic arrhythmia characterized by ventriculo-atrial dissociation on the electrocardiogram. The risk o f atrioventricular block with radiofrequency ablation is high and long -term drug treatment is often effective. Atrial ectopic tachycardia is also automatic and may originate in the left or right atrium. Drug su ppression is possible but radiofrequency ablation offers the prospect of cure. All three arrhythmias are likely to persist long term. Drug t reatment with class IC or class III drugs is most likely to be effecti ve. Rate control or arrhythmia suppression are likely to lead to impro vement or normalization of left ventricular function.