| RR&R | regular rate and rhythm |
|---|---|
| RSR | regular sinus rhythm; relative survival rate; right superior rectus [muscle] |
| SMR | senior medical resident; sensorimotor rhythm; severe mental retardation; sexual maturity rating; ske... |
| SR | sarcoplasmic reticulum; saturation recovery; scanning radiometer; screen; secretion rate; sedimentat... |
| UHR | underlying heart rhythm |