Association of PATENT FORAMEN OVALE with the METABOLIC HEAT PRODUCTION and CORE TEMPERATURE relationship in men

A patent foramen ovale (PFO) is an intracardiac shunt between the right and left atria that allows deoxygenated blood to flow from the right atrium through the shunt to the left atrium. Previous studies from our laboratory have shown that men with a PFO (PFO+) had a higher body core temperature (Tcore) of ~0.3-0.4 °C during active heating (exercise), passive heating (hot tub immersion) and passive cooling (cold tub immersion). This project was a retrospective analysis that examined unpublished metabolic and core temperature data from several previous studies from our laboratory. Specifically, we analyzed individual subject’s metabolic heat production (Hprod) as a possible mechanism for the increase in Tcore observed in PFO+ men. During active heating, there was a strong correlation between Hprod and Tcore during stages 25% Max to 90% Max, indicating that an increase in the Hprod due to increased exercise intensity is contributing to an increase in the Tcore in both groups. Both passive heating and passive cooling demonstrated a curvilinear relationship between Hprod and Tcore. There were similar relationships between Hprod and Tcore during active heating, passive heating, and passive cooling for PFO+ and PFO- subjects, indicating that both groups had similar changes in Tcore in response to the various stressors. Despite having a significantly higher Tcore, PFO+ subjects had the same Hprod as PFO- subjects at each exercise/time stage during all three conditions. This result implies that Hprod is not a mechanism that causes PFO+ subjects to have a higher Tcore than PFO- subjects