[Anaerobic threshold in the evaluation of heart function in patients with rate-responsive pacemaker]

It is very difficult to evaluate the ability of carrying out physical exercise in patients with rate responsive (RR) pacemaker (PM). However, the anaerobic threshold (AT) proved to be a useful parameter in the evaluation of cardiac function. The AT can be easily reproduced and not influenced from emotional aspects of both the patient and the physician, moreover being under maximum and then easy to achieve. Aims of our study were: to evaluate if the cardiopulmonary stress test can represent a method to be used for a more correct rate responsive pacemaker programming; to compare the data obtained of 3 rate responsive pacemakers steered by different sensors. We have studied 24 patients, of whom 10 with Activitrax (A), 8 with Meta (M), and 6 with Phymos MPT (P) pacemakers. Patients were submitted to symptoms limited cycloergometer stress test at 2 different settings: fixed rate at 70 b/min; increasing rate at until 85% of maximum heart rate for each patient, with range 0 + 10 W/min. Gas exchange data were continuously collected using an automated system (Medical Graphic System 2001) based on Whipp and Wasserman's method.(ABSTRACT TRUNCATED AT 250 WORDS)