Which part needs to be explained? I think I understood the comment and I’m not in the industry. AED is an initialism for the electrical shock device you can use to (maybe) reboot the heart’s OS when it locks up. Catheters are some kind of tube that gets implanted to bypass a non-functional part of the heart. Catheter procedures improving caused the change, not AEDs (apparently), so it’s somewhat misleading to show an AED instead of something about catheters.