Heavy Heart and it's meaning

Words have meaning and the meaning of words have origins. In Exodus 7:14, Pharaoh has a heavy heart. What does this mean? I feel the Jews were heavily influenced by the culture they were enslaved to. I have seen other ethnic cultures make adaptions to their by the influence of the world around. I find this very interesting.
The following I found searching the internet.

The Book of the Dead is full of spells and rules to help a person travel safely on his journey through the Afterlife. Above, you see the king facing his last and most important test – the weighing of the heart. On the left, he and his wife enter the area where he is to be judged.The Egyptians thought that a person’s heart showed all their good and bad deeds.Any’s heart is placed on some scales and weighed by the god Anubis (with the black jackal head) against the feather of truth. If it is lighter than the feather he will survive and continue into the next world. If it is heavier then he will be eaten by the Devourer, the monster on the right who is part-lion, part-hippopotamus and part-crocodile. Next to the Devourer stands Thoth, the god of truth (with an ibis head). He is checking that the weighing is fair.

Now we know what we are talking about when we speak of a "heavy heart".