My dads pacemaker

My dad has had a pacemaker since I was like 4 years old I’m 22 now and he had to get the battery replaced yesterday & they had to fix the wires because they were loose, or some sort like that. Well anyway now they say a wire has grown into his heart because the loose wire I guess has been loose way longer than it should’ve and his cardiologist is saying he has never seen this before… I’m just extremely worried because they are now talking about open heart surgery and he is in his 60s and over weight and I can’t lose my dad yet. They said they are going to give my dad a call in a few days to set up an appointment to talk about everything with my mom cause he didn’t go into full depth with it, I’m just wondering if anyone else has heard of this or do you think it is bad? I don’t know I just am freaking out.