Twenty-eight patients with a grade 2 and 3 atrioventricular block and an implanted DDD pacemaker were repeatedly subjected to a bicycle ergometric test with a maximum load of the AV block (VV30), ventricular stimulation (VVI70) and DDD stimulation. The maximum work capacity and maximum heart rate achieved on VVI30 were 92 + xi 38 W and 61 +/- 27/min. The maximum work capacity increased on DDD by 49% while on VVI70 only by 22% (p < 0.00001) and the maximum heart rate increased on DDD by 185%, while on VVI70 only by 41% (p < 0.00001). The authors found a significant correlation between the increment of the maximum work capacity on DDD, as compared with that on VVI70 (d maximum work capacity) and maximum work capacity at VVI70 (r = -0.53, p < 0.01), maximum work capacity on VVI30 (r = -0.437, p > 0.03), maximum heart rate at VVI70 (r = -0.415, p < 0.004) and age (r = 0.56, p < 0.005). The d maximum work capacity was significantly higher in patients without their own ventricular activity during the load on VVI70 (28 +/- 24% vs. 13 +/- 8%, p < 0.05 (in patients who did not attain the upper frequency limit of DDD stimulation (30 +/- 25% vs. 14 +/- 9%, p < 0.004) and in patients above 60 years of age (37 +/- 26% vs. 14 +/- 10%, p < 0.002).

Keywords: Adolescent; Adult; Aged; Exercise Test; Female; Heart Block /physiopathology/; Humans; Male; Middle Aged; Pacemaker, Artificial; Work Capacity Evaluation