sounds more like gasteritis,or something,,,if you can associate it with greasy goods exct,,its not your heart!!,,,if it were you might not be writing in now!
my dad had a hiatal hernia
till thr day he died,and it never presented him with issues from food and stuff,,,
things to watch with hernia...
..posture!!!!...dont slouch exct,,sit straight,,you say you noticed this when sitting
2....dont eat too much,or too late in the evening,,,this causes issues with hernia.