Fortunately, I have a high pain tolerance, but I did let out some pretty good groans. Didn't figure it was a good idea to say what I thought while strapped down and under the control of people causing the pain.
The worse part was when they started sewing up the inside and the technologist said "Wait a minute, we lost lead one". Followed by the surgeon saying, "Damn, this is frustrating". That was already the second time he placed that lead and he had to remove two layers of stiches and try with a third. Mind you, it was already about 2.5 hours from when I was given the local in my skin. Once he replace that lead and tested, he again connected the pacemaker and re-tested. Then he re-did the internal stiches, each of which I felt. Then came the real pain. He had to push the device under my skin pushing VERY hard, re-testing, and then sewing me up, again feeling each stich. At that point, I thought the pain was over - nope! They had covered my while chest and part of my neck with a self-sticking plastic cover (like tape). The nurse started pulling it off with me yelling slow down and wet it. He didn't. I've got a LOT of minor skin damage.
A freaky part was the flatline warning that sounded several times. After the two leads are placed they cut the nerves and your heart stops. Then it starts up with the operating room equipment and later with the pacemaker but at each transition, you hear the flatline warning for a few seconds.
The surgery is supposed to take 1-3 hours. Took 4.