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Importance of AV Synchronous Pacing During Low Intensity Exercise Evaluated by Oxygen Kinetics
Author(s) -
RICKLI HANS,
PETER HANS,
ROCCA BRUNNERLA,
MACCARTER DEAN J.,
DURU FIRAT,
CANDINAS RETO
Publication year - 2000
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.1540-8159.2000.tb00798.x
Subject(s) - medicine , cardiology , intensity (physics) , heart rate , kinetics , sick sinus syndrome , treadmill , sinus rhythm , respiratory exchange ratio , anesthesia , blood pressure , atrial fibrillation , physics , quantum mechanics
It has been shown that dual chamber pacing with preservation of AV synchrony (ODD) is superior to fixed rate ventricular (VVI) or rate responsive ventricular (VVIR) pacing modes, as evaluated by ventilatory response to exercise. Previous studies have focused on the benefits of maintained AV synchrony at maximal exercise. However, there are limited data comparing O 2 kinetics in different pacing modes during low intensity exercise, representing the majority of daily activities. This study aimed to provide an evaluation of different pacing modes using O 2 kinetics during low intensity exercise. Nineteen patients (age 61 ± 18 years) with complete AV block underwent low intensity treadmill exercise (35 W) with simultaneous evaluation of symptoms and O 2 kinetics in three pacing modes. The first test was performed in DDD mode followed by a second test in VVIR mode with a programmed heart rate corresponding to the sinus rate during the first test. After 6 minutes of each test, the mode was switched from DDD to VVIR and vice versa. The third test was performed in VVI mode at 70 beats/min. O 2 kinetics were defined as O 2 deficit (time [rest to steady state] ×Δ VO 2 —ΔVO 2 [rest to steady state]) and mean response time (MRT) of oxygen consumption (O 2 deficit/ΔVO 2 ). The O 2 deficit was 551 ± 134 ml in DDD pacing, 634 ± 139 mL in VVIR pacing, and 648 ± 179 mL in VVI pacing (P = 0.001). MRT was 49 ± 7.8 seconds in DDD pacing, 54.7 ± 9.5 seconds in VVIR pacing, and 57.4 ± 11.0 seconds in VVI pacing (P = 0.002). Ten (53%) patients developed symptoms during switch from DDD to VVIR mode whereas the switch from VVIR to DDD mode was not perceived by any patient (P < 0.001). In conclusion, our study shows an impact of AV synchronous pacing and heart rate adaptation on O 2 kinetics during low intensity exercise that correspond to casual daily life activities. Our observations may have clinical implications for the management of patients with complete AV block.