ECG Review

A Fast Heart with Chest Pain

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.

Clinical Scenario

The patient whose 12-lead ECG and rhythm strip is shown above had chest discomfort at the time this tracing was recorded. In light of this history, how do you interpret the tracing?

Interpretation

The rhythm is rapid and regular at a rate of about 145/min. The QRS complex is narrow, and there is no sign of atrial activity. Thus, the rhythm is a regular SVT (supraventricular tachycardia). Since there is not even the slightest indication of a sinus P wave, and no deflections in any of the 12 leads even remotely suggest flutter activity, the rhythm most likely is PSVT (paroxysmal supraventricular tachycardia). Deep and diffuse ST segment depression and T wave inversion is associated with the tachycardia. Tachycardia itself can be the cause of ST-T wave abnormalities, even as marked as the changes that are seen here. Thus, there is no way to tell from this tracing alone if acute ischemic injury is occurring. Follow-up ECGs after the tachycardia has stopped will be needed. Even then, marked ST-T wave abnormalities may sometimes persist for a day or two as a "post-tachycardia syndrome." As a result, serial troponins and a brief period of hospital observation may be needed to ensure that infarction has not occurred, even if symptoms promptly resolved after conversion of the rhythm.