There are several types of hiatal hernias (aka paraesophageal hernias):
The first type of hiatal hernia is called a sliding hiatal hernia. This is the most common type of hiatal hernia and is a result of the lower esophagus and top of the stomach sliding up together into the chest through the hiatus.
Other, less common types of hiatal hernias are called paraesophageal hernias. These occur when a section of the stomach goes up into the chest next to the esophagus, or when other organs such as colon, intestine, or spleen go up through the hernia defect into the chest. These types of hernia can be more dangerous because they are not always associated with symptoms and can result in the stomach tissue becoming twisted off from its blood supply resulting in “strangulation” of the stomach. In most cases, however, people have mild symptoms such as heartburn or gastroesophageal reflux disease (GERD) due to the structural changes associated with the hiatal or paraesophageal hernia.