[Sinus dysfunction and nodo-hisian conductive disorders. Indication for definitive cardiac stimulation].

A consecutive series of 80 patients has been the object of intracavitary electrophysiological studies, including a study of sinus function and of node/His conduction, before implantation of a definitive cardiac pacemaker. Investigation of the sinus yielded normal or insignificant results in 32 cases. It revealed certain criteria of "major" sinus dysfunction (TRSC 1000 ms; more than compensatory return cycles where there was SAP) in 39 cases, made up of 18/20 in group I (documented evidence of sinus malfunction), 10/14 in group II (sinus bradycardia less than or equal to 55/mn), 9/44 in group III (A-V conduction defects), and 2/2 in group IV (paroxysmal supraventricular tachycardia); criteria of "minor" sinus dysfunction (TRSC between 550 and 1000 ms, TECASA greater than 210 ms) were found in only 9 cases (group I--1; group II--2, group III--6). The association of sinus malfunction with node/His conduction defects was found in 29 cases, the site of the AV block being nodal in 7 cases, intra-His in 2 cases, infra-His in 10 cases, and a combination of nodal and infra-nodal in 10 cases. In 59 cases, the severity of the AV block (40 cases), of the sinus malfunction (17 cases) or of the sinus bradycardia (2 cases) was already obvious, and investigation of the sinus was not critical in determining the indications for a cardiac pacemaker. In 21 cases, however, this investigation was a determining factor, and most especially in 12 cases from group II. Sinus investigation seems to represent, in addition, a valuable indicator for the decision to install a pacemaker in a certain number of litigious cases.