CPX (CARDIOPULMONARY EXERCISE TESTING) FI NDINGS IN RESPIRATION-GUIDED AND QT-DRIVEN PACEMAKERS

This study used ergospirometry with quantification of gas exchange par ameters to analyze the beneficial effects of two sensors for rate resp onsive pacing: QT-interval and minute ventilation (MV). Bicycle exerci se testing was performed with modulating VVIR pacing modes in random s equence. Rate responsiveness effected a mean increase of exercise tole rance of 31.1 % in the QT group and 22.6 % in the MV group. With both systems maximal oxygen uptake increased by 29.4 % (QT) and 28.3 % (MV) . Oxygen consumption at the anaerobic threshold was improved by 28.3 % (QT) and 32.1 % (MV). The increase of cardiopulmonary parameters achi eved by rate responsiveness was significant (p < 0.05) without signifi cant difference in comparison between both groups. Despite the initial ly delayed rate increase at the onset of exercise mediated by the QT-i nterval, the programmed upper rate limit was satisfactorily attained b y both principles. Thus, both sensors - minute ventilation and QT-inte rval - provide an adequate rate modulation in response to exercise and a marked improvement of cardiopulmonary work capacity.