[Sinus-node recovery time in the sick-sinus syndrome (author's transl)]

Sinus-node recovery times were measured, before and after atropine administration, in 21 patients with the clinical diagnosis of sick-sinus syndrome. The results were compared with those reported by other workers. It is concluded that sinus-node recovery times of more than 1 400 ms are most likely due to sinus-node damage (sick-sinus syndrome); normal recovery times are rare in such patients. The diagnosis of the syndrome is strengthened if the recovery time remains abnormally long even after atropine. Further useful diagnostic information can be obtained from the total stimulation phase (duration until restoration of the basic rhythm), this being overall longer in patients with the syndrome than in normal subjects. The increased incidence of A-V nodal rhythms before restoration of the basic rhythm is another indication of organic damage to the sinus node, especially if it also occurs after atropine. The significance of a recovery time which is prolonged before but normal after atropine is less clear: a raised sensitivity to vagotonic influences may be the determining factor here.