Exercise chemosensitivity in heart failure: ventilatory, chronotropic and neurohormonal responses.
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.
Moura
Lídia Zytynski
LZ
Instituto do Coração do Hospital de Clínicas, FMUSP, São Paulo, SP, Brasil. lidia.zyt@cardiol.br
Guimarães
Guilherme Veiga
GV
Pires
Philippe Vieira
PV
Cruz
Fátima
F
Stopa
Gabriela
G
Bocchi
Edimar Alcides
EA
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
D018377:Neurotransmitter Agents