I did a bit of research on this, as we have a friend who we invited to our place and she has a pacemaker.
The machines can pick them up, but they do not harm the pacemaker, but the advice is to get a Doctor's letter to show at the Customs, perhaps a Turkish translation of the letter too.
Unfortunately our friend cannot now come as she has another medical problem which just occurred and the insurance is expensive and she is now too concerned about travelling.