Video Thermography Uncovers Relationship Between Volume Status and Temperature in Heart Failure

Aims Thermoregulation is a fundamental aspect of mammalian homeostasis. Skin blood flow has a key role to play in thermoregulation. Heart failure (HF) can disrupt thermoregulation. Infrared thermography (IRT) offers a non-invasive method to map skin temperature (Ts). The aim of this study was to investigate the relationships between IRT-assessed thermoregulation, circulatory volume, and exercise in patients with HF, studied in a euvolaemic state and again after diuretic and saline challenges. Methods and results Based on ejection fraction (EF), patients were stratified into HF with reduced, mildly reduced, and preserved phenotypes (HFrEF, HFmrEF, and HFpEF). Ten healthy volunteers served as controls. Participants underwent an IRT videotaped treadmill exercise test on separate days, either in a euvolaemic state or 30 min after saline or diuretic challenge. Ninety stable HF patients, including 40 with HFrEF, 20 with HFmrEF, and 30 with HFpEF were enrolled. IRT-measured Ts differed between HF patients and controls, both at rest and during exercise. Regardless of volaemic state, the decline in Ts during exercise was significantly delayed and smaller for patients with HFrEF compared to HFmrEF or HFpEF. Conclusions Patients with HF have reduced skin blood flow and impaired thermoregulation compared to healthy controls. Patterns of Ts response appear similar for HFmrEF and HFpEF but different for HFrEF. Further research is warranted to determine the effect of impaired thermoregulation on exercise duration in patients with HF and whether it could be useful a therapeutic biomarker indicating restoration of a normal physiological response to exercise.