ECG Challenge: Tennis Player With an Irregular Pulse

Philip J. Podrid, MD


May 18, 2020

The correct diagnosis is normal sinus rhythm, right bundle branch block (RBBB), left anterior fascicular block, bifascicular disease, blocked (nonconducted) premature atrial complexes in a trigeminal pattern, left atrial hypertrophy or abnormality (Figure 2).

Figure 2. Courtesy of Dr Podrid.


A repeating pattern of two QRS complexes followed by a pause—ie, group beating—causes a regularly irregular rhythm. The underlying rate, based on the two regularly occurring QRS complexes (*), is 66 beats/min.

The QRS complexes are wide (0.14 sec) and have an RBBB morphology with an RR' in V1 (→) and broad terminal S waves in leads I, V5-V6 (←). The axis is extremely left between -30° and -90° (positive QRS complex in lead I and negative QRS complex in leads II and aVF). Because the QRS complex morphology in leads II and aVF is rS, this diagnosis includes a left anterior fascicular block.

Another etiology for an extreme left axis is an old inferior wall myocardial infarction in which there is an initial deep Q wave in leads II and aVF. A left anterior fascicular block in combination with RBBB is termed bifascicular disease.

A P wave precedes each QRS complex (+) and the PR interval is stable (0.22 sec). The QT/QTc intervals are slightly prolonged (440/460 msec) but normal when the prolonged QRS complex duration is considered (400/420 sec). The P waves are positive in leads I, II, aVF, and V4-V6. Therefore, this is a normal sinus rhythm. The P waves are prominently notched in leads II, aVF (P mitrale) and V3-V6 and are negative in leads V1-V2, however, indicating a left atrial abnormality or left atrial hypertrophy. Although the PR interval is slightly prolonged, this is probably caused by a broad P wave rather than prolonged atrioventricular nodal conduction.

There are several long RR intervals or pauses. There is no P wave observed during the pause, so this does not represent a second-degree atrioventricular block. There are notches seen on the upstroke of the T wave of each second sinus QRS complex (↑). As T waves should be smooth in upstroke and downstroke, these notches are superimposed P waves that are early or premature—ie, nonconducted or blocked premature atrial complexes. Because they occur after every two sinus complexes, the diagnosis is atrial trigeminy.

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.

Follow Philip J. Podrid, MD on Twitter @PPodrid

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