INITIAL CLINICAL-EXPERIENCE WITH A NEW DUAL SENSOR SSIR PACEMAKER CONTROLLED BY BODY ACTIVITY AND MINUTE VENTILATION

Fourteen patients were implanted with a single chamber dual sensor pac emaker (Legend Plus(R)) that measures minute ventilation (VE) via vari ations in impedance between a bipolar lead and the pacemaker case, and activity via a piezoelectric crystal bonded to the pacemaker case, Ch ronotropic incompetent patients were exercised on a treadmill and a bi cycle in dual sensor mode. Activity only indicated pacing rate was mea sured using a strap-on pacemaker. Both implanted and strap-on pacemake rs were adjusted to yield a steady-state pacing rate of 100 beats/min during hall walk. Pacing rate, VE, and oxygen uptake (VO2) were measur ed continuously. Linear curve fit analysis slopes for plots of VE vers us pacing rate during exercise (1.33-1.49) compared favorably to value s reported in normals. Peak pacing rates achieved for treadmill and bi cycle testing for dual sensor mode were higher than activity mode alon e. Slopes of heart rate to VE or VO2 were not significantly different (P < 0.05) for dual sensor mode in contrast to activity alone. In conc lusion, the Legend Plus dual sensor rate adaptive pacing therapy deliv ered pacing rates more proportional to VE and VO2 under different type s of exercise than rates indicated by a strap-on pacemaker in activity mode.