Superiority of multiprogrammable to nonprogrammable VVI pacing: a comparative study with special reference to management of pacing system malfunctions.

Analysis of pacing system malfunctions was performed in 374 patients at initial implantation or at pulse generator and lead replacement during a period of 55 months. A total of 150 nonprogrammable pacemakers were implanted in 148 patients, while 236 multiprogrammable pacemakers were implanted in 226 patients. The purpose of the analysis was to investigate the occurrence and management of malfunction unrelated to pacemaker/lead failure or lead dislodgement. The nonprogrammable group was followed for 3-53 months (median, 36). Malfunction occurred in 18 patients (12.0%): muscle stimulation in 14; exit block in three; sensing problem in one. Surgical correction was necessary in 14 of 18 cases. The multiprogrammable group was followed for 3-52 months (median, 12). Malfunction occurred in 30 cases (12.7%): muscle stimulation in 22; threshold increase in seven; sensing problem in one. Only seven of these patients required surgical correction as 23 cases were successfully managed by reprogramming alone. Malfunctions occurred during a period of several days to 36 months (median, 2.3 months). The difference in rate of secondary surgical intervention was significant (p less than 0.01). Measurements during reoperation in the nonprogrammable group showed that at least 40% of late malfunctions would have been correctable by reprogramming alone. Thus, multiprogrammability is of significant value for noninvasive correction of malfunctions unrelated to pacemaker and lead failures, predominantly muscle stimulation and threshold elevation.