The heart is a metaphysical gyroscope that defies the tug of external imbalances and always is pointed at the right path. It also indicates the slightest of deviation detected in any given reality of a situation. It makes no difference how much things are distorted and disguised, nothing can turn the heart. When the deviation in a reality is especially steep it can present an inordinate amount of tension for the person stuck between the heart and the distorted reality. If someone isn’t well-versed in reading their own heart and have the wrong reference values for their emotions then they’ll just shut down their heart to minimize interference and dissonance.
In fact, iblees relies on flooding the mind with a lot of fragmentary signals that all oppose the heart in a bid to “flush out” a person from being grounded in their heart. This is how he misguides; by unsettling and disorienting one’s conscious connection to the heart.