ECG Challenge: A 70-year-old man with a history of chronic obstructive pulmonary disease treated with inhalers presents to his pulmonologist with increasing shortness of breath that he thinks may be related to chronic obstructive pulmonary disease. He has noted intermittent palpitations. His physician checks his blood pressure, which is 100/70 mm Hg, and also notes a rapid heart rate prompting an ECG.
There is a regular rhythm at a rate of 150 bpm; however, there are 2 long RR intervals (↔). The QRS complex is narrow (0.08 s), and it has a normal morphology and normal axis between 0° and 90° (positive QRS complex in leads I and aVF). The QT/QTc intervals are slightly prolonged (300/470 ms). There is nonspecific T-wave flattening. There is evidence of atrial activity (+) best seen in leads V1 and V3, although atrial waveforms can be seen in other leads (v). The RP interval (0.28 s) is longer than the PR interval (0.18 s). Hence, this is a long RP tachycardia. There are several causes for a long RP tachycardia, including the following:
Atypical atrioventricular nodal reentrant tachycardia, ie, fast-slow
Ectopic junctional tachycardia
Atrioventricular reentrant tachycardia
Atrial flutter with 2:1 block
Importantly, during the 2 long RR intervals, there is evidence of atrial activity (*) and the PP interval is constant (└┘) with a rate of 300 bpm. The only regular atrial rhythm at a rate >260 bpm is atrial flutter. Therefore, the underlying rhythm is atrial flutter with primarily 2:1 atrioventricular conduction. The long RR intervals are the result of a higher degree of atrioventricular block (ie, 3:1 and 4:1).
Please go to the journal’s blog, OpenHeart, for more ECG Challenges: http://goo.gl/tQPNFp. Challenges are posted on Tuesdays and Responses on Wednesdays.
- © 2016 American Heart Association, Inc.