The correct diagnosis is atrial flutter with variable block (Figure 2).
The rhythm is regular at a rate of 150 beats/min; however, there are two long RR intervals (↔). The QRS complex is narrow (0.08 sec) 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 msec). There is nonspecific T-wave flattening. Evidence of atrial activity (+) is best seen in leads V1 and V3 although atrial waveforms are also apparent in leads I, II, avR, and aVF (v). The RP interval (0.28 sec) is longer than the PR interval (0.18 sec). This is considered a long RP tachycardia. Etiologies for a long RP tachycardia include:
Atypical atrioventricular nodal reentrant tachycardia; ie, fast-slow
Ectopic junctional tachycardia
Atrioventricular reentrant tachycardia
Atrial flutter with 2:1 block
Of note, evidence of atrial activity (*) appears during the two long RR intervals, and the PP interval is constant (⊔) with a rate of 300 beats/min. The only regular supraventricular rhythm with an atrial rate > 260 beats/min is atrial flutter. Therefore, the underlying rhythm is atrial flutter with primarily 2:1 atrioventricular (AV) conduction. The long RR intervals are the result of a higher degree of AV block (ie, 3:1 and 4:1).
Philip Podrid, MD, is an electrophysiologist, a professor of medicine and pharmacology at Boston University School of Medicine, and a lecturer in medicine at Harvard Medical School. Although retired from clinical practice, he continues to teach clinical cardiology and especially ECGs to medical students, house staff, and cardiology fellows at many major teaching hospitals in Massachusetts. In his limited free time he enjoys photography, music, and reading.
You can follow Dr Podrid on Twitter @PPodrid
Medscape Cardiology © 2022 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: ECG Challenge: Uncontrolled COPD or Something Else? - Medscape - Jun 27, 2022.