Should the Treatment Response Cause Alarm?
June 15, 2017 2 minutes read
By Ken Grauer, MD
Professor Emeritus, Family Medicine, College of Medicine, University of Florida
Dr. Grauer reports that he is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
The rhythm in the figure below was observed as a previously healthy young adult was receiving treatment for his “palpitations.” He was hemodynamically stable at the time.
Should what we see be cause for alarm? The patient is hemodynamically stable. The first nine beats show a regular supraventricular tachycardia (SVT) rhythm at a rate of 185-190 beats/minute. No atrial activity is seen during this run. The rhythm changes beginning with beat #10.
After the run of SVT, it is easiest to look next at beats #11 and #12. Both beats clearly are ventricular, since the QRS complex is wider and completely different in appearance from QRS complexes during the SVT run at the beginning of the tracing.
Beat #10 manifests an intermediate morphology, both of the QRS complex and of the ST-T wave, between the narrow beats before it and the ventricular couplet that follows. Beat #10 is a fusion beat, which means it is due to simultaneous occurrence of a supraventricular and ventricular beat. Therefore, beats #10-12 constitute a three-beat salvo of ventricular tachycardia.
Sinus rhythm then is seen to occur beginning with beat #13. Another ventricular couplet follows (beats #14 and #15), with the tracing ending in a regular sinus rhythm at a normal rate.
The rhythm in the figure begins with a nine-beat run of atrioventricular nodal reentry tachycardia (AVNRT). The rate of this SVT rhythm is too fast for atrial flutter, with a 2:1 conduction. Sinus tachycardia rarely goes this fast. Abrupt conversion to sinus rhythm (beat #13) supports the diagnosis of AVNRT, which is a common cause of “palpitations” in the young adult age group.
We do not know if conversion to sinus rhythm was achieved by a vagal maneuver, by medication, or by a combination of the two. Regardless, the point to emphasize is that it is a common and normal phenomenon to see PVCs (including ventricular couplets or salvos) at the time of conversion from a reentry tachycardia to sinus rhythm. This is not cause for concern and should not prompt additional workup.
For more information and further discussion about this case, please visit: http://bit.ly/2pONdWR.
The rhythm in the figure was observed as a previously healthy young adult was receiving treatment for the patient described as 'palpitations.'
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