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COMPARATIVE STUDY
JOURNAL ARTICLE
Optimal maximum tracking rate of dual-chamber pacemakers required by children and young adults for a maximal cardiorespiratory performance.
INTRODUCTION: Children and young adults require a higher maximum tracking rate (MTR) for physical activity. The objective of the present study was to observe whether higher MTR of 170 or 190 beats per minute (bpm) have a positive impact on the maximal cardiorespiratory capacity of children and young adults in comparison with a lower MTR of 140 bpm.
METHODS: Fifteen patients with atrioventricular block and normal sinus-node chronotropic function (age 7-24 years) with DDD- (14) or VDD-pacemakers (PM) (1) were enrolled. First, the MTR was adjusted to 140 bpm for 6 weeks and elevated in a second step to 170 or 190 bpm. At the end of each period two cardiopulmonary exercise tests, a 24-hour ECG and a PM test were performed.
RESULTS: All patients increased their maximal heart rate (139.0 +/- 1.0 vs 177.0 +/- 10.0 bpm, P < 0.001), peak cardiorespiratory capacity (2.4 +/- 0.6 vs 2.8 +/- 0.7 W/kg, P < 0.001), peak oxygen uptake (28.3 +/- 7.0 vs 35.7 +/- 9.5 mL/kg/min, P < 0.005), and oxygen uptake (23.7 +/- 7.4 vs 29.3 +/- 8.4 mL/kg/min, P < 0.02) at the anaerobic threshold. There were no evident heart rhythm disturbances with elevated MTR. Patients with a Wenckebach behavior of the PM had an attenuated increase of maximal cardiorespiratory performance.
CONCLUSION: Children and young adults with DDD-/VDD-PM benefit from an elevated MTR by an increased cardiorespiratory capacity, without having more heart rhythm disturbances. A Wenckebach behavior of the PM should be avoided.
METHODS: Fifteen patients with atrioventricular block and normal sinus-node chronotropic function (age 7-24 years) with DDD- (14) or VDD-pacemakers (PM) (1) were enrolled. First, the MTR was adjusted to 140 bpm for 6 weeks and elevated in a second step to 170 or 190 bpm. At the end of each period two cardiopulmonary exercise tests, a 24-hour ECG and a PM test were performed.
RESULTS: All patients increased their maximal heart rate (139.0 +/- 1.0 vs 177.0 +/- 10.0 bpm, P < 0.001), peak cardiorespiratory capacity (2.4 +/- 0.6 vs 2.8 +/- 0.7 W/kg, P < 0.001), peak oxygen uptake (28.3 +/- 7.0 vs 35.7 +/- 9.5 mL/kg/min, P < 0.005), and oxygen uptake (23.7 +/- 7.4 vs 29.3 +/- 8.4 mL/kg/min, P < 0.02) at the anaerobic threshold. There were no evident heart rhythm disturbances with elevated MTR. Patients with a Wenckebach behavior of the PM had an attenuated increase of maximal cardiorespiratory performance.
CONCLUSION: Children and young adults with DDD-/VDD-PM benefit from an elevated MTR by an increased cardiorespiratory capacity, without having more heart rhythm disturbances. A Wenckebach behavior of the PM should be avoided.
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