EKG Lead placement question

[ACNP 2B S1S2RRR]

Hi, all. I am doing my practicum and am about to graduate. I was looking at my patient's EKG strips after a sleep study (leads were placed on his back during sleep study), and I noticed inverted U waves on the EKG strips. I know that this is caused by myocardial ischemia amongst other things, but I was wondering if the appearance of the strips had anything to do with the fact that the leads were placed on the back. I also noted ST segment elevation.

can someone describe how the EKG strip will normally look when the leads are placed on the back? it seemed as though the depth of the spike ending the QRS complex was really exaggerated, dipping almost as low as one would expect in a pacing spike.

I asked my preceptor, but she told me that she's not very good at reading EKG strips. She's only 25 years old, so I don't think she's been a nurse for a really long time.

thanks to all who take the time to try and help me =)