Incidence of rhythm disorders in hyperthyrosis with special respect of old age form.

Sinus tachycardia and atrial fibrillation are frequent features in hyperthyrosis while sinus node dysfunction is regarded as a rare complication. Bradycardia may cause diagnostic problems mainly in atypical hyperthyrosis of the old age. The authors analysed distribution and age related association of the rhythm disorders in hyperthyrosis. In case of the appearance of Sick Sinus Syndrome (SSS), parameters representing the function of sinus node were studied by electrophysiological investigations. Above the age of 50 years incidences of atrial fibrillation and SSS were significantly increased. The abnormal sinus node function proved to be reversible in a portion of the cases. In old age, in case of occurrence of the symptoms of SSS, possibility of hyperthyrosis also should be considered, especially when indication of permanent pacemaker is established.