What is a hietal hernia?

Following a recent fluoroscopy at my surgeon's office, it was learned that I have developed a hietal hernia above my Lap Band. At this point, it is unknown how long I have had the hernia, as I have not had any noticeable symptoms. This issue will be repaired during my VSG surgery. 

A hietal hernia is problematic in those who have a Lap Band as it limits the effectiveness of the device. It is possible (and likely) that part of the reason I have not had success with the band is due to the presence of the hernia. My current understanding of the issue is that when I eat, the food has been extending into the esophageal area (which the hernia is allowing), thus allowing a greater intake of food and reduced feeling of fullness. Thats the best way I can explain it. 

Like I mentioned, a great many individuals that have hietal hernia experience negative symptoms including acid reflux, GERD, etc. I have been fortunate not to have experienced this thus far.