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* From the Department of Medicine (Drs. Wonisch, Lercher, Scherr, and Maier), Division of Cardiology, Medical University, Graz, Austria; Institute of Sports Physiology (Dr. Pokan), University of Vienna, Austria; Institute of Sport Sciences (Dr. Hofmann), Karl-Franzens University, Graz, Austria; and Human Performance Laboratory (Dr. von Duvillard), Department of Health, Kinesiology & Sports Studies, Texas A&M University, Commerce, TX.
Correspondence to: Manfred Wonisch, MD, PhD, Department of Medicine, University Hospital, Division of Cardiology, A-8036 Graz, Auenbruggerplatz 15; e-mail: manfred.wonisch{at}meduni-graz.at
Study objectives: Patients with chronic heart failure and implanted cardioverter-defibrillators (ICDs) may have a higher incidence of new-onset or worsening heart failure requiring hospitalization with dual-chamber ICDs compared with single-chamber ICDs.
Design and setting: The purpose of this study was to show the impact of permanent right ventricular (RV) pacing on exercise capacity and related cardiorespiratory parameters in patients with chronic heart failure and ICDs.
Patients and interventions: Seventeen patients with chronic heart failure and a dual-chamber ICD performed cardiopulmonary exercise testing (CPX) on 3 different days. After CPX 1, patients were randomized either to back-up pacing or permanent RV pacing. After 3 months, CPX 2 was performed and patients changed groups (crossover design); CPX 3 was performed after 3 additional months.
Measurements and results: Maximal values for workload (108 ± 46 W vs 117 ± 48 W, p < 0.01), oxygen uptake (
O2) [21.0 ± 5.3 mL/min/kg vs 22.5 ± 6.4 mL/min/kg, p < 0.05], oxygen pulse (13 ± 3.7 mL vs 14 ± 4.0 mL, p < 0.05), and metabolic equivalent (6.0 ± 1.5 vs 6.4 ± 1.8, p < 0.05) were significantly lower with permanent RV pacing compared to back-up pacing. Workload,
O2, and oxygen pulse were significantly reduced at the ventilatory anaerobic threshold, while workload and
O2 were significantly lower at the respiratory compensation point. No differences were found for maximal heart rate, minute ventilation
E, and respiratory exchange ratio. The
E/carbon dioxide production slope was significantly steeper with permanent RV pacing compared to back-up pacing.
Conclusions: Permanent RV pacing significantly reduced maximal and submaximal measures of exercise. For patients with chronic heart failure and sufficient atrioventricular conduction, every effort should be made to minimize permanent right ventricular pacing.
Key Words: cardiopulmonary exercise testing dual-chamber implantable cardioverter defibrillator maximal oxygen consumption minute ventilation/carbon dioxide production slope respiratory compensation point ventilatory anaerobic threshold ventilatory efficiency
This article has been cited by other articles:
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Z. Goldberger and R. Lampert Implantable Cardioverter-Defibrillators: Expanding Indications and Technologies JAMA, February 15, 2006; 295(7): 809 - 818. [Abstract] [Full Text] [PDF] |
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