I've been on Methadone 90 mg for 3-4 months now for chronic pain, and I've heard that a particular interval can be lengthened? in the heart due to this medication. My doctor hasn't said anything about it, but my primary care dr did say I needed to have an EKG the next time I came in because she hears a heart murmur and it is louder than before. I've been sooo very sleepy the past two weeks - could this be related to the problem that occurs with Methadone or the heart murmur? I am 50 years old, 300 pounds, in a wheelchair so I get little to no exercise, and have been on lots of meds the past 25 years. I know, I'm a heart attack waiting to happen.