I love this because its clever, however, there is no disconnect between the heart and the brain. The physiological state of your heart and its rhythms are closely tied to your state of mind. Though it remains true that when acting out of reason, we often seem cold. Whereas, when we act based on emotion, we often seem quite irrational or careless towards anything but how we feel. In either case, the coherency of our thoughts is likely mirrored in the variability of our heart rate. The more it fluctuates, the more flexible you probably are and the more you can bend and maneuver yourself around your troubles to the point of effortless resiliency.