A misleading ECG

A 10-year-old girl was brought to her primary care provider by her mother because she complained of chest pain earlier that morning. She also reported abdominal pain and nausea. The patient’s medical history was remarkable for asthma. She had no surgical history and no history of tobacco or alcohol exposure. Her current medications included montelukast (Singulair) and loratadine (eg, Claritin, Alavert) on a daily basis and pseudoephedrine (Sudafed PRN) every other day. The patient weighed 109.5 lb. Her physical examination and a review of systems were normal. The patient’s vital signs included a blood pressure of 108/72 mm Hg, heart rate of 86 beats/min, and a temperature of 97.2°F. A urinalysis was negative and her blood glucose measured 84 mg/dL after a light breakfast. An electrocardiogram (ECG) revealed a ventricular rate of 74 beats/min, PR interval of 144 ms, QRS duration of 70 ms, and QT/QTc interval of 352/374 ms. The P axis was +126°, R axis was +171°, and T axis was +143°. The ECG was faxed to our office for consultation.

Diagnosis: Left atrial myxoma.

This is a good example of leads misplacement. The ECG shows sinus rhythm, with a ventricular rate of 74 beats/min. P wave and T wave inversions are visible in leads I and aVL. Notice in lead aVR that the P waves and T waves are upright. This is a tip-off that something is awry. The waves should always be inverted because the electrical reading in lead aVR is going from right to left, opposite the electrical conductivity of the heart, which goes left to right. A tried and true reminder when reading ECGs is to look over the entire ECG. If something looks peculiar, check the placement of the leads. Going back to the basics can save you and your patient much unnecessary grief. At first glance, this ECG appeared to demonstrate possible high lateral ischemia. A repeat ECG was completely normal. This young lady and her mom were very relieved, as was the provider.

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