A Scooped ST Tachycardia
By Ken Grauer, MD, Professor, Department of Community Health and Family Medicine, University of Florida Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
Figure: 12-lead ECG and lead II rhythm strip obtained from a 83-year-old woman with "rapid heart rate."
The 12-lead ECG and lead II rhythm strip in the Figure were obtained from a 83-year old woman who presented with rapid heart rate. She was on no antiarrhythmic medications. How would you interpret her ECG?
There is minor irregularity in this supraventricular tachycardia that occurs at a rate of between 120-130/minute. At first glance in lead II, the rhythm looks like sinus tachycardia with a scooped ST segment. This is not what is occurring.
The key to interpreting this rhythm lies in lead III, which is best viewed by stepping back a little bit from the tracing. Doing so reveals the suggestion of a saw-tooth pattern that is really not evident in any other lead. Application of a vagal maneuver confirmed atrial flutter as the diagnosis. Although the atrial rate of untreated flutter is usually between 250-350/minute (most often very close to 300/minute) this tracing illustrates how atrial flutter can occasionally occur at a slightly slower rate despite no treatment with antiarrhythmic drugs.