Two hundredpatients with implantedpacemakers werefollowed in a pacemaker clinic over a period of 3years. The follow-up times ranged from I to 36 months, with a mean of 22 months. The material represents 366 patient-years ofpacing and 361 pacemakers. One hundred and twenty replacements were done. Most of these were elective (93%) and based on gradual deterioration of the pacing detected by photoanalysis of the generator impulse. Of the single variables the duration of the impulse and the discharge rate were most revealing; recording changes in these two variables led to 96 per cent failure detection. There were 28 deaths within the follow-up time: 3 of them were related to pacing failure and 5 were possibly so. When these sudden fatal events were added to the sudden nonfatal failures not detected by the routine control system a I6 per cent failure rate of detection emerged. The total annual mortality was 7.7 per cent. The mortality caused by pacing failures was 2 2 per cent per annum.After the primary descriptions of the significance of impulse analysis in detecting pacemaker failures (Davies and Sowton, i964;-Nickel, I964; Knuckey, McDonald, and Sloman, I965) organized special pacemaker clinics have gained wide acceptance. The primary goal is to prevent sudden pacing failures, with the associated mortality and morbidity, and to get the maximal life span out of each implanted unit (Siddons and Sowton, I967; Thalen et al., I969). While it is evident that the number of emergency replacements is greatly reduced, they still occur (e.g., Parsonnet et al., I970; Furman, Escher, and Parker, I97Ia), and a number of patients succumb outside hospital from pacing failure without detailed data on the mode of death.A pacemaker clinic has been in operation in Helsinki University Central Hospital since I968. This report is based on the analysis of its efficiency in preventing pacing failures during a period of three years.
Patients and pacemakersDuring the time of analysis 207 patients were followed in the clinic. Seven of them were lost to follow-up (3 transferred to other hospitals, 2 moved abroad, 2 not traced), leaving 200 patients, 103 women and 97 men, for analysis. The age ranged from 28 to 88, with a mean of 6i years. The follow-up ranged from I to 36 months, Received 2 JUIy I973. with a mean of 22 months. All together this represents 366 patient-years. The pacemaker material consisted of 36I units, 207 of which were Elema-Sch6nander (Types 139, I52, 153), io6 Vitatron (Types 150, 400 R), and 48Medtronic (Types 5841, 5842 d, 5843 d, 5860, 5862, 5868, 5870). Only two units functioning normally were replaced solely because they approached the maximal life span reported by the manufacturer. These have been excluded from the analysis. All the other units have been followed to the point when clear-cut indications for replacement became evident or sudden failure occurred.Endocardial pacing was accomplished in 20I instances while i6o units were connected to epicardial electrodes inserted either earlier or simultaneously throug...
