Abnormalities of cardiac conduction in sinus node disease. Correlation with clinical findings.

His bundle recordings, sinus recovery time and the response to atropine were studied in 28 patients with symptomatic sinus node disease. The electrophysiological data were correlated with the clinical picture and the course of the disease. The marked prolongation of sinus recovery time and a decidedly diminished responsiveness to atropine may increase the accuracy of clinical assessment of the disease but negative results of these tests do not exclude even serious dysfunction of the node. The His bundle electrogram provides a more thorough evaluation of AV conduction and should be taken into account when permanent electrotherapy is being considered.