Monomorphic Ventricular Tachycardia

Report:

Ventricular tachycardia 150/min

Comment:

In lead V1 the QRS is a monophasic R wave with left rabbit ear taller than the right, with duration just over 0.14”. These features, along with bizarre frontal plane axis, are sufficient to diagnose ventricular tachycardia, especially in the setting of known past myocardial infarction. The presence or absence of symptoms does not have any diagnostic significance.

This is a monomorphic (uniform, unifocal) VT. The complexes are identical; the only differences are seen in lead V4, where the size variation is obviously due to a respiratory swing.

By convention, the tachycardia is called sustained if it lasts 30 seconds or longer; therefore a standard 10-second ECG cannot determine whether the paroxysm is sustained or not. It would still be able to show a non-sustained variety, provided it lasts less than 10 seconds.

Below (Fig 1a) is a sample of the patient’s underlying rhythm, atrial flutter, slowed down by amiodarone to 198/min, in 2:1 and 4:1 block, and old inferior infarction. History of myocardial infarction makes a broad-complex tachycardia more likely to be ventricular in origin.