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Heart failure patients have impaired thermoregulatory response during exercise (884.2)
Author(s) -
Morris Norman,
Royston Danielle,
Jayasinghe Rohan,
Sabapathy Surendran
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.884.2
Subject(s) - thermoregulation , medicine , cardiology , cardiac output , heart failure , skin temperature , hemodynamics , biomedical engineering
Objective: During a thermoregulatory challenge such as exercise in the heat, skin blood flow (SkBF) must rise so as to maximise radiant, convective and evaporative heat loss. There is some evidence to suggest that in Heart Failure (HF) the rise in SkBF is blunted during passive heat exposure. Indeed, HF patients may be unable to adequately increase cardiac output to service multiple vascular beds during a thermoregulatory challenge. The aim of this study was to compare the thermoregulatory responses to exercise in the heat in a group of HF patients (n=7, 62 + 7 yr, NYHA Class I‐II) and age‐matched healthy controls (CON; n=6, 63 + 8 yr). Methods: HF and CON exercised for 60 min heat (30 o C, 60% relative humidity) at ~70% peak oxygen uptake (VO 2 ). Core temperature (T c ) and skin temperature (T sk ) were measured continuously. Skin blood flow was measured every 10 minutes using Laser Doppler Flowmetry. Skin conductance was determined from the ratio of SkBF and mean arterial pressure. Results: HF patients exercised with a significantly (p<0.05) lower metabolic heat load when compared to CON (VO 2 : HF 1.26 + 0.32; CON 1.83 + 0.52 l/min). Despite this, both HF and CON had a similar and significant increase (P<0.05) in T c (HF: pre: 37.2 + 0.4, end ex: 38.2 + 0.4 o C; CON: pre 37.3 + 0.2, end ex: 38.2 + 0.4 o C) and T sk (HF: pre: 33.0 + 0.6, end ex: 35.0 + 0.5 o C; CON: pre 32.6 + 0.6, end ex: 35.7 + 0.6 o C). HF patients had a significantly lower (p<0.01) increase in SkBF (HF: 101 + 30; CON: 302 + 64 AU) and skin conductance (HF: 1.0 + 0.6; CON: 2.9 + 1.1 AU). Conclusion: Despite exercising at a lower metabolic heat load, HF patients had a similar increase in T c but lower SkBF when compared CON. Our results suggest HF patients may have impaired thermoregulation secondary to blunted circulatory heat dissipation in HF.