Is a heart block a one time thing or a chronic disorder in the heart?

"Depends": Heart blocks are very variable from fairly benign (first degree) to pretty serious (complete heart block). They can be transient and benign like mobitz type 1 or they can be permanent. Some heart blocks may be more serious but can be reversed if their is an underlying problem such as lyme disease or medication reaction. Often times however a pacemaker may need to be implanted.