What causes an irregular z-line other than barrett's esophagus or a hiatal hernia?

Normal variation: The z-line, where the esophagus lining connects to the stomach lining varies quite a bit from person to person. Not everyone has a straight circle -- that's why it's called the "z"-line, because an irregular border is normal. Some things that can make it more abnormal could be reflux of bile or acid into the esophagus, poor esophageal squeezing, or just a normal variation. Good health!

Esophagitis: Normally, the z line is a regular which is why it's called the z line. In other words, the line is sharply demarcated but wavy as it goes around the esophagus. Inflammation of this can blur the border as well as barrett's esophagus. A hiatal hernia has no effect on the z line per se. Hope this helps!