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Effects of carvedilol on oxygen uptake and heart rate kinetics in patients with chronic heart failure at simulated altitude.

AbstractBACKGROUND:
The response to moderate exercise at altitude in heart failure (HF) is unknown.
METHODS AND RESULTS:
We evaluated 30 HF patients, (NYHA I-III, 25 M/5 F; 59 ± 10 years; LVEF = 39.6 ± 7.1%), in stable clinical conditions, treated with carvedilol at the maximal tolerated dose. We performed a maximal cardiopulmonary exercise test (CPET) with ramp protocol at sea level to evaluate patients' performance and two moderate intensity constant workload CPETs (50% of peak workload) at sea level (normoxia) and simulated altitude (hypoxia). Oxygen uptake (.VO2 ) and heart rate (HR) on-kinetics at constant workload were assessed calculating the time constant (τ) with a monoexponential equation. .VO2 and HR were higher in hypoxia (0.944 ± 0.233 vs 1.031 ± 0.264 l/min; 100 ± 23 vs 108 ± 22 bpm; p < 0.001). On-kinetics showed a different behavior of τ being .VO2 faster in hypoxia (67.1 ± 23.0 vs. 56.3 ± 19.7 s; p = 0.026) and HR faster in normoxia (49.3 ± 19.4 vs. 62.2 ± 22.5 s; p = 0.018). Ten patients, who lowered oxygen kinetics in hypoxia, had greater HR increase during maximal CPET suggesting lower functional beta-blockade. The higher τ of .VO2 in hypoxia is likely to be due to a peripheral effect of carvedilol mediated either by β- or α-receptor.
CONCLUSION:
HF patients performing moderate exercise at 2000 m simulated altitude have 20% .VO2 increase without trouble at the beginning of exercise when treated with carvedilol.
AuthorsMarlus Karsten, Mauro Contini, Claudia Cefalù, Gaia Cattadori, Pietro Palermo, Anna Apostolo, Maurizio Bussotti, Damiano Magrì, Elisabetta Salvioni, Stefania Farina, Susanna Sciomer, Aparecida Maria Catai, Piergiuseppe Agostoni
JournalEuropean journal of preventive cardiology (Eur J Prev Cardiol) Vol. 19 Issue 3 Pg. 444-51 (Jun 2012) ISSN: 2047-4881 [Electronic] England
PMID21450573 (Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Adrenergic Antagonists
  • Carbazoles
  • Propanolamines
  • Carvedilol
Topics
  • Adrenergic Antagonists (therapeutic use)
  • Aged
  • Altitude
  • Carbazoles (therapeutic use)
  • Carvedilol
  • Chronic Disease
  • Exercise Test
  • Female
  • Heart Failure (diagnosis, drug therapy, metabolism, physiopathology)
  • Heart Rate (drug effects)
  • Humans
  • Hypoxia (metabolism, physiopathology)
  • Kinetics
  • Male
  • Middle Aged
  • Myocardium (metabolism)
  • Oxygen Consumption (drug effects)
  • Propanolamines (therapeutic use)
  • Treatment Outcome

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