ATRIAL FIBRILLATION w/

Slow Ventricular Response

Rate:              Atrial rate usually 400 - 600 bpm;

                       ventricular rate variable

Rhythm:          Ventricular rhythm usualyy irregularly

                        regular

P Waves:         No identifiable P waves, very fine F

                        waves

PR Interval:    Not measurable

QRS Complex: 0.10 sec or less

ATRIAL FLUTTER

Rate:              Atrial rate usually 250 - 450 bpm;

                       typically 300 bpm

Rhythm:          Atrial regular, Ventricular regular  

                        irregular                     

P Waves:         No identifiable P waves "saw tooth" F

                        waves are present

PR Interval:    Not measurable

QRS Complex: 0.10 sec or less, but may be widened if

                         waves are buried in the QRS

PREMATURE ATRIAL COMPLEX

Rate: Atrial rate usually within normal range but depends on the underlying rhythm

Rhythm: Regular with premature beats

P Waves: Premature (occurring earlier than the next expected sinus P wave), positive (upright) in lead II, one before each QRS complex, often differ in shape from sinus P waves - may be flattened, notched, pointed or biphasic or lost in the preceeding T wave

PR Interval: May be normal or prolonged depending on the prematurity of the beat.

QRS Complex: Usually 0.10 sec or less, but may be wide (abberant) or absent depending on the prematurity of the beat; the QRS of the PAC is similar in shapes to  those of the underlying rhythm unless the PAC is abnormally conducted.  

waves are buried in the QRS

NOTE: A PAC is not a rhythm. It is a complex that appears in an underlying rhythm.