Are there any other reasons for advance Parole?

How can I find this out?

My Brother has been diagnosed with a chronic heart condition and is severely depressed. I was wondering if they will allow him to go back and see our family for a while. Does it have to be a sick family member only?

I would apply. Of course it only lists "educational, employment, or humanitarian" reasons but those categories appear to be broad and open to interpretation, which in your particular case your brother's diagnosis seems to fall under humanitarian.

Valid reason for humanitarian

Absolutely. I think just proving his condition and stating he would like to see his family would be good enough. If you REALLY wanted to be sure, maybe say he is going to consult with a specialist down there?

Get a Doctor's note stating your brother's chronic heart condition. I think they will allow you to visit him.

Humanitarian reasons for oneself also count. Example seeking treatment abroad because its cheaper there. Depression might be a good enough reason, especially if he has a psychiatrist/therapist willing to write a statement that he/she believes your brother's depression would improve if he would be able to visit his family abroad.