Final answer:
A hiatal hernia occurs when a small portion of the stomach pushes through the hole in the diaphragm where only the esophagus is supposed to go through, causing symptoms such as heartburn and acid reflux.
Step-by-step explanation:
The condition that the patient is experiencing, where a small portion of the stomach is pushing through the hole in the diaphragm where only the esophagus is supposed to go through, is called a hiatal hernia. A hiatal hernia occurs when the upper part of the stomach bulges through the diaphragm into the chest cavity. This can lead to symptoms such as heartburn and acid reflux.