[Preliminary study of a double chamber pacemaker with diagnostic function].

Pacemakers with diagnostic functions have been implanted for several years. The main clinical indication for these devices is unexplained syncope. Some reports of the use of diagnostic pacemakers have shown that in patients with unexplained syncope, paroxysmal bradycardia was a common finding after implantation. Until recently, diagnostic functions were only available in VVI pacemakers, which explains the limitations of this type of function in determining the mechanism of the bradycardia. The aim of this study was to assess a new dual-chamber diagnostic pacemaker functioning in the VDI mode. Twenty-three patients were implanted with this type of unit and followed up for an average of 153 days. The number of episodes of bradycardia detected was 6 +/- 10 (median: 3). The interval between the installation of the algorithm and the date of the first episode of bradycardia was 67 +/- 86 days (range: 12-306 days). The mechanisms of the bradycardia were atrioventricular block (6 patients), sinus node dysfunction (6 patients) and blocked atrial bigeminy in 1 patient. These conclusions were drawn from analysis of chains of markers. Bradycardia was recorded during the day or during the day and night in 21 patients; bradycardia was exclusively nocturnal in only 2 patients. The tolerance of the algorithm was good on the whole but 3 patients reported minor symptoms related to the relative bradycardia inherent with this type of algorithm. Four other patients had a VDI pacemaker syndrome which was completely corrected by reprogramming the pacemaker to the standard DDD mode. These new devices represent a technical advance in the field of diagnostic pacemakers.(ABSTRACT TRUNCATED AT 250 WORDS)