Cardiology In Critical Care
Arrhythmia Recognition
Normal Sinus Rhythem
Normal Sinus Rhythm
Impulses originate in the SA node regularly at a rate 60-100 per minute in adults and at faster rates in older children (90-110), small children (100-120) and infants (120-160). P waves upright in L2 and negative in AVR and of uniform size and contour from beat to beat. PR interval 0.12-0.20 sec and constant when A-V conduction normal; PR prolonged and/or variable when A-V block present. Each P followed by QRS with resulting P:QRS ratio 1:1 QRS ratio 1:1. QRS less than 0.11 sec or QRS wide and bizarre when bundle branch block present. RR intervals may be slightly irregular especially in the young and elderly.
| Heart Rate |
Rhythm | P Wave | PR Interval (in seconds) |
QRS (in seconds) |
|---|---|---|---|---|
| 60 - 100 bpm | Regular | Before each QRS, identical | .12 to .20 | < .12 |
There have been Visitors
to this website.