Humans need a healthy heart - both physically and spiritually.
When the Bible mentions the heart, it is not referring to the organ that pumps blood throughout the human body.
Jeremiah 17:9-10 says, "The heart is deceitful above all things, and desperately wicked: who can know it? I the LORD search the heart, I try the reins, even to give every man according to his ways, and according to the fruit of his doings."
So what does this word "heart" refer to?
According to WikiAnswers, "The heart is the organ more at the core of the body. That culture used the heart as a symbol of the inner man, the deepest thoughts, the deepest feelings, the deepest intentions. So deep at times they were incomprehensible, and in some ways, unknowable and difficult to observe - known only by God."
Meanwhile, a functioning physical heart is a necessity for human life.
Sunrise Hospital produced this infographic about having a healthy physical heart which reports that "heart disease is the #1 killer of American men and women."