Atrial Rhythms

Atrial flutter: HR > 100 (with RVR), regular rhythm, P waves replaced by “Flutter” waves (Saw-tooth pattern), PR interval not measurable, normal QRS complexes

Atrial fibrillation (AFib): HR > 100 (with RVR), irregular rhythm, undulating/ wavy baseline with no discernible P waves, PR interval not measurable, normal QRS complexes

Supraventricular tachycardia (SVT): HR 150 to 250, regular rhythm, P waves not visible (buried within QRS complex), PR interval not measurable, normal QRS complexes

Premature atrial complexes (PACs): Ectopic beat that originates in atrial tissue and comes early in cycle. P wave is usually abnormal in shape but could look normal if ectopic site is near SA node; otherwise normal EKG with normal rate, rhythm, P wave, PR interval and QRS complexes

Multifocal atrial tachycardia (MAT): HR > 100, irregular rhythm, three or more types of distinct P wave shapes, variable PR interval, normal QRS complexes. If HR is normal (60 to 100), it is referred to as “Wandering atrial pacemaker” rather than MAT.