title: Exercise chemosensitivity in heart failure: ventilatory, chronotropic and neurohormonal responses.
abstract: BACKGROUND
  Heart failure (HF) is associated with resting increased peripheral and central chemosensitivity which may correlate with an increased ventilatory response to exercise. However, its sensitivity in HF during exercise was never really reported.
  
  
  OBJECTIVE
  We tested if stimulation of central and peripheral chemoreceptors in HF patients could modulate ventilatory, chronotropic, and neurohormonal response during submaximal exercise.
  
  
  METHODS
  We investigated central and peripheral chemosensitivity in 15 HF and 7 control (C) comparing response through three 6 minute walking tests conducted in a treadmill with : room air, hypoxia, and hypercapnia (in a randomic order).
  
  
  RESULTS
  RR at room air C and HF was 17±2 and 22±2 (p<.0001); at hypoxia 17±1 and 23±2 (p<.02); at CO25% was 20±2 and 22±5 (p<.02). Tidal volume (TV) at room air was 1.25±0.17 and 1.08±0.19 (p<.01); at hypoxia 1.65±0.34 and 1.2±0.2 (p<.0001); at CO25% 1.55±0.46 and 1.29±0.39 (p<.0001). At rest the increment in HF was higher for VE (C 33±40%, HF 62±94%, p<.01), HR(C 7±10%, HF 10±10%, p<0.05) at rest. During hypoxia exercise increment in HF was higher for RR (C 1±4, HF 11±6,p<.05), HR (C 12±2, HF 14±3, p<.05), VE/VO₂ (C -4±18%, HF 24±21%, p<.01), HR/VO₂ (C -26±11%, HF 11±5%, p<.01), VE/WD (C 36±10%, 46±14, p<.05%) and HR/WD (C 18±8%, HF 29±11, p<.01). During HF hypoxia exercise NO reduced, and IL-6, aldosterone levels increased. Neurohormonal levels unchanged in C.
  
  
  CONCLUSIONS
  Exercise peripheral and central chemosensitivity are increased in HF and may modulate respiratory pattern, cardiac chronotropic, and neurohormonal activity during exercise.
authors: Instituto do Coração do Hospital de Clínicas, FMUSP, São Paulo, SP, Brasil. lidia.zyt@cardiol.br
authors: Lídia Zytynski
authors: LZ
authors: Moura
authors: Guilherme Veiga
authors: GV
authors: Guimarães
authors: Philippe Vieira
authors: PV
authors: Pires
authors: Fátima
authors: F
authors: Cruz
authors: Gabriela
authors: G
authors: Stopa
authors: Edimar Alcides
authors: EA
authors: Bocchi
mesh_terms: D000328:Adult; D000388:Air; D002628:Chemoreceptor Cells / Q000502:physiology*; D004812:Epidemiologic Methods; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018377:Neurotransmitter Agents / Q000097:blood*; D012119:Respiration; D012146:Rest / Q000502:physiology; D016138:Walking / Q000502:physiology
chemical_list: D018377:Neurotransmitter Agents