This is an example of frequent atrial premature beats occurring in a "bigeminy" pattern (atrial bigeminy). The second beat of every couplet is narrow, and subtle P waves are seen preceding each in lead II. This rhythm would be clinically appreciable as a regularly irregular rhythm. Consider causes like excess caffeine and theophylline, but this may well be due to intrinsic atrial disease too.
NOTE: EKG's are for internal educational purposes of the University of Massachusetts Department of Family Medicine. Please do not forward without permission from Dr. Golding!
