ECG Challenge: Teen With His First Seizure

Philip J. Podrid, MD


November 06, 2019

The correct diagnosis is long QT, torsade de pointes (Figure 2).

Figure 2. Courtesy of Dr Podrid.


The first QRS complex is narrow and supraventricular (*). It is followed by a rapid and irregular rhythm with a rate of up to 300 beats/min. The QRS complexes are unusual and show marked variability in amplitude, interval, morphology, and axis (^). This arrhythmia is polymorphic ventricular tachycardia that is nonsustained.

The arrhythmia terminates abruptly, and a narrow QRS complex is preceded by a P wave (+). It can be seen that the QT interval of this supraventricular complex is very long (0.56 sec) as a result of a broad T wave (↔). This is indicative of prolonged repolarization, and the associated polymorphic ventricular tachycardia is known as torsade de pointes.

This is a long QT syndrome. If the supraventricular complex had a normal QT interval, this would be called polymorphic ventricular tachycardia, which is most often the result of ischemia.


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