Hiatus Hernia and breast reconstruction?

The hiatal hernia is located inside your chest and the breast  reconstruction will be superficial to the chest cavity.
You should mention it to the anesthesiologist because they can  give you anti-reflux medication.

Thanks for your question and the answer is all good news.
Your sub-muscular breast implants are no where near your hiatus hernia. Your reconstructive surgery will not affect your hernia in any way - although you should remind your anaesthetist about it, as reflux during surgery can be a problem.
I hope this helps.