Monomorphic Ventricular Tachycardia: Minuscule V1 Rabbit Ears

Report:

Monomorphic ventricular tachycardia 188/min

Comment:

The monophasic R complex in V1 has two small “rabbit ears”; the left one is mostly taller than the right (looking at the rabbit from behind). This is a classic marker of ventricular ectopic origin10. In this example it is barely perceptible and even less so in the VT recurrence a year later (Fig 9b). If the right one is taller, the probability of ectopy is only 50% - one may as well toss a coin. Of course, a monophasic R or a qR in lead V1 indicates ventricular ectopy in its own right. The LAD in the frontal plane remains non-contributory.

There was no response to Xylocaine in Casualty and the VT was cardioverted by a 200 Joule countershock. Xylocaine is relatively non-toxic and one cannot argue too much against its use as a first-line therapy of VT. On the other hand, it is not the most potent of antiarrhythmics. Procainamide or amiodarone appear better; perhaps our manuals should be re-written11.

Post-cardioversion ECG (Fig 9a), like in a previous case (Case 8) showed marked ST segment depression, indicating an underlying coronary artery disease. Perhaps immediate post-tachycardia traces are not the best ones to base one’s diagnosis upon: this patient had normal coronary arteries at angiography.

A good example of rabbit ears is seen in the following case (Fig 10). 9a. The “plane” ST segment depression is a classical response to ischæmia. But not in this case. 9b. Same VT a year later. The rabbit ears in V1 are useless and the complex should be regarded as a monophasic R wave. The precordial sequence is diagnostic of VT. 10. 79 year old lady with ischæmic cardiomyopathy, experiencing left arm pain and dizziness.