@danab I know there are basic instructions needed to ensure the operative site stays intact, doesn't become infected as healing takes place, and to ensure that the newly implanted leads don't detach, but the details of these instructions depends a lot on the individual doctor who does the surgery and his/her practice.

I had soluble stitches, some steristrips closing my pacemaker wound and the whole thing was covered with a Tegederm patch, with strict instructions NOT to remove or touch this dressing before the 4-5 day wound check visit with the nurse in the office. The instructions said I could shower after day 2 but not get the wound wet. I managed that by taping plastic wrap over the Tegederm and securing that with waterproof electrical tape while I showered, and facing away from the shower head as I showered so no water fell directly on the area.

The instructions also say not to lift the arm on the side of the pacemaker above the head, or behind the back for some time ( approximately a month, not longer) or to lift anything heavier than 10 lbs for some time. The reason for this is that theoretically such movement could dislodge the newly implanted leads, although from what I have read today's leads have attachments ( many of them actually have threads at the tips that can be screwed into the cardiac tissue) that aren't likely to become dislodged, unless the lead has been poorly or improperly attached. So dislodgement isn't likely to happen these days even if a person inadvertently lifts the arm prior to that month- we've all done that and worried about having yanked out leads, at least once during our recovery period!
That said, my sister, who also had sick sinus syndrome, did manage to dislodge one of her pacemaker leads about a week or so after implantation- they got that report from her remote monitor and she had to go back and have that lead replaced. I've always attributed that dislodgment to her roughhousing with her then 2 year old twin boys, but I can't say for sure how it happened. I figure that it may well be that engaging in sports, or activity requiring strenuous use of that arm during the recovery period might tend to dislodge new pacemaker leads, and that's where following the instructions of the doc who implanted the pacemaker as to what can be done and when such activity can be resumed is so important.

In any case, once those leads are in place for a time the endothelial lining of the vessels in which they're placed grow around the leads so the leads become embedded and won't go anywhere!

I think the ICDs are still somewhat larger than pacemakers, so I'd think you'd naturally see a larger lump with an ICD but that also depends on the area and depth of placement, the person's own build and the fat or tissue around where the pacemaker is placed. If the person is very thin, has little fat around the tissue where it's placed, the pacemaker will be more visible. I'm padded enough and my pacemaker is small enough that you can't really see much of a lump- I'd have to point it out for someone to notice it- especially as you can barely see the scar either. But if you touch the area you can feel the pacemaker. But that's me.