What is a Hiatal Hernia?
Your chest is separated from your abdomen by a domed sheet of muscle called the diaphragm.  To reach your stomach, your esophagus has to pass through an opening, or hiatus, in the diaphragm.  When the tissue around the hiatus weakens, part of the stomach may protrude through the opening into the chest cavity.  This abnormality at the diaphragm hiatus is termed hiatal hernia.  A hiatal hernia is caused by a weakening of the anchoring tissues of the gastroesophageal junction to the diaphragm, perhaps due to increased pressure within the abdomen such as sometimes results from obesity or trauma.  While some people are born with a hernia, factors such as heavy lifting, aging, and even some medications can cause the sphincter to weaken, allowing the stomach to push into the chest.
Symptoms 
Substernal fullness or ache, heartburn, difficulty swallowing, shortness of breath, bloating or hiccups after meals are all symptoms of  hiatal hernia.   
Diagnosis
Your evaluation will include having a physical exam and a complete medical history. The doctor will want to know how severe the problem is and how it is limiting or affecting your lifestyle.  You will be asked to have diagnostic testing, which will include: Esophageal Motility,  24 hour pH study and ocassionally a upper endoscopy.
What if I need surgery?
Surgery for  a hiatal hernia is indicated once the symptoms of the hernia become severe enough to alter your quality of life and is refractory to medical management.  The surgey is done through a laparoscopic approach.  4 - 5 small holes are made and the operation is completed in about 60 - 90 minutes.  A 24 hr stay is usually all that is required and most people return to work in 1 week.