Pathology of sinoatrial node. Correlations with electrocardiographic findings in 111 patients

Histological study of the sinoatrial node (SAN) was performed in 111 patients in order to estabilsh correlations between the ECG findings and the anatomical lesions. This series includes both patients with sinus rhythm and patients with atrial arrhythmias. The results are as fololows: (a) the amount of nodal cells in the SAN was found to be inversely proportional to the age of the patients (p less than 0.001); (b) normal sinus rhythm was present in some cases with severe fibrosis of the SAN; (c) the present study does not support lesions of the SAN as responsible for atrial fibrillation; (d) chronic sinoatrial block was associated with extensive lesions of the approaches of the AV node or the AV node itself; (e) the auricular tachycardia-bradycardia syndrome was associated in most cases with both lesions of the main feature of the SAN lesion. The pathogenesis of these fibrotic lesions are discussed.