Rate: Slow (< 60 bpm) Rhythm: Regular P Wave: Normal PR Interval: Normal (0.12-0.20 sec) QRS: Normal (0.06-0.10 sec)
The locus of stimulation is the same as normal sinus rhythm, just now the rate will be less than 60 bpm.
Sinus bradycardia is a sinus rhythm of under 60 beats per minute. It is normal in children, in well-conditioned athletes and other healthy people. It also occurs naturally during sleep. Severe sinus bradycardia is a type of sick sinus syndrome. External Source: http://www.patient.co.uk/doctor/bradycardia