[Comparative study of endocavitary recording and the 24-hour electrocardiogram in the study of sinus function. Apropos of 174 cases].

We compared the results of electrophysiological investigations of sino-atrial node function in a series of 174 patients (including the sino-atrial conduction time (SACT) according to the method of Narula and Strauss, the corrected sino-atrial recovery time (CSART) and, in, 22 patients, the atropine test) with the results of 24 hour Holter monitoring. 73 patients presented a pathological Strauss curve, 47 had a prolonged SACT (Strauss' method) and 19 had a pathological CSART. Of the 22 bradycardic patients, the injection of atropine relieved the bradycardia in 45.5 per cent of cases. 19 patients showed signs of sino-atrial node dysfunction on the 24 hour Holter recording. Of the 35 patients with a surface electrocardiogram (ECG) suspicious of sino-atrial node dysfunction, 21 (60%) had a prolonged SACT and 13 (37.1%) had a pathological CSART: 15 of them (42.8%) showed major electrophysiological abnormalities and 19 (54.3%) had a positive Holter. In two-thirds of the cases of pure sino-atrial bradycardia, the results of electrophysiological and Holter investigations were normal; in 50 per cent of cases of sino-atrial block and/or pause on the surface ECG, major abnormalities were found on both electrophysiology and the Holter monitor. The SACT, estimated according to the method of Strauss, is discorsdant with the SACT estimated according to Narula's method in 46 p. cent of cases. It seems that Strauss' SACT was more sensitive in our study. In 102 cases (59.3%), the SACT and the CSART were concordant. In 10 cases, the SACT was normal while the CSART was pathological and in 42 cases, the SACT was pathological while the CSART was normal.(ABSTRACT TRUNCATED AT 250 WORDS)