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Influence of the Pacing Rate on the Atrioventricular Conduction Time During Aerobic and Anaerobic Exercise: Basic Concepts for a Dromotropically Controlled Rate Responsive Pacemaker
Author(s) -
MEINE MATHIAS,
HEXAMER MARTIN,
WERNER JÜRGEN,
ISRAEL CARSTEN W.,
MÜGGE ANDREAS,
LEMKE BERND,
BARMEYER JÜRGEN
Publication year - 1999
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1999.tb00411.x
Subject(s) - medicine , anaerobic exercise , cardiology , cardiac pacing , heart rate , aerobic exercise , electrical conduction system of the heart , electrocardiography , physical therapy , blood pressure
The dromotropic pacemaker concept needs a rate responsive algorithm in which the pacing rate is controlled by the atrioventricular conduction time (AVCT). To develop basic concepts for such a rate responsive algorithm, the influence of the pacing rate on the AVCT was investigated. Seven patients (62 ± 7.8 years) with sick sinus syndrome and intact atrioventricular conduction underwent two cardiopulmonary exercise tests (CPX) on a treadmill. According to the determination of the anaerobic threshold (AT) and the patients maximum capacity in the first incremental CPX the work rate for two exercise levels below and above the AT were chosen for the second constant workload CPX. The calculation of the optimal pacing rate (HR opt ) was based on the oxygen uptake (VO 2 ) during exercise after reaching steady‐state conditions. According to the increase of the V 2 from 14.8 ± 2.3 mL/min per kilogram during aerobic work (38.3 ± 16.0 W) to 19.4 ± 4.7 mL/min per kilogram during anaerobic work (80.6 ± 32.3 W), the HR opt was calculated to be 98.6 ± 6.9 beats/min and 116.4 ± 4.7 beats/min. Starting from HR opt , the pacing rate was increased (overpacing) and decreased (underpacing) by about 5 beats/min every minute. At optimal pacing rate the AVCT decreased significantly from 233.0 ± 30.5 ms during aerobic work and to 226.4 ± 27.3 ms during anaerobic work (P < 0.05). Whereas overpacing induced a significant prolongation of the AVCT during aerobic work (4.17 ± 1.78 ms per 10 beats/min) and anaerobic work (3.84 ± 1.60 ms per 10 beats/min), underpacing yielded a significant shortening of the AVCT by about 4.49 ± 2.64 ms per 10 beats/min during aerobic work and 4.75 ± 1.87 ms per 10 beats/min during anaerobic work (P < 0.01). The slopes of the regression lines of the relationship between AVCT and pacing rate were not significantly different. Based on the reciprocal relationship of heart rate (HR) and AVCT, basic concepts may be established for a dromotropic rate responsive algorithm.