ECG Review

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."

Clinical Scenario:

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?

Interpretation/Answer:

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.