The authors examined 27 patients with chronic complete atrioventricular block (AVIII) and an implanted pacemaker with rate responsive pacing (RRP), controlled by atrial frequency (DDD stimulation--19 patients) or the length of the QT interval (VVIR pacing--8 patients). The loading test in AVIII ventricular stimulation 70/min (VVI 70) and RRP proved a more than double asset of MKP in RRP, as compared with VVI 70 (55.5 +/- 43.3% vs. 24.3 +/- 34.1%, p less than 0.001). The difference was greater in acquired than in congenital AVIII (27.7 +/- 18.5% vs. 8.4 +/- 4.1%, p less than 0.002) and in patients where the maximum heart rate on VVI did not exceed 70/min, as compared with the remainder (29.3 +/- 19.1% vs. 12.7 +/- 8.1%, p less than 0.002). The difference of MPK in RRP and VVI 70 was inversely correlated with MPK on VVI 70 (r = -0.412, p less than 0.03). MPK on AVIII and MTF on VVI 70 (r = -0.386, p less than 0.05). RRP in patients with AVIII thus causes a double increase of MPK, as compared with VVI pacing. A greater asset can be expected in patients with acquired AVIII, with a lower working capacity and heart rate recorded during the loading test before implantation.

Keywords: Adolescent; Adult; Aged; Cardiac Pacing, Artificial /methods/; Female; Heart Block /physiopathology/; Heart Rate; Humans; Male; Middle Aged