Try this:
http://www.arrl.org/tis/info/pacemaker.html
More stuff there than I cared to sort through, most very technical. But in short, yes, strong RF feilds can interfere with your pacemaker, but precautions can be taken. The writers seem a lot more concerned about cell phones, but offer precautions for those as well.
I think I'd be more concerned about VHF/UHF than HF, and probably think about doing more QRP? Also, with your background, you might make sure your operation areas are not too hot, having a low field strength, good grounds and not to many harmonics running around.