Explain A Blockage Behind The Heart In Laymans Terms Please.

Explain a blockage behind the heart in laymans terms please. My brother who is 75 Yrs old was recently was admitted to the hospital and found to have a blockage in the back of his heart. I'm sure there are numerous ways to resolve this problem; however, what is the most widenly used remedy?
I appreciate any short response you could provide, if possible. Much thanks.