The Epsilon wave
Let’s talk about epsilon (ε) wave.
The epsilon wave can be defined as an electric signal of depolarization observed between the end of the QRS complex and the beginning of the T wave.
Criteria
✅ Small positive deflection (notch or upright) between the end of the QRS and the beginning of the T wave.
✅ Usually is best seen in the right precordial leads. However, (ε) waves could be found in the leads of the frontal plane, especially in the inferior leads, when the LV is involved.
Causes include: arrhythmogenic right ventricular dysplasia, right ventricular infarction, infiltrative disease, post ablation procedure, others
Guy Hugues Fontaine (1936-2018) was a French cardiologist and electrophysiologist.
The first recordings of the ε wave were reported by Fontaine et al. in the 1970's, and four years later Fontaine called it an ε wave. The reason that led Dr. Fontaine to choose ε is not clear. It could be that its shape reminded him of the Greek letter epsilon (ε) as suggested by Surawicz and Knilans in their classical book on electrocardiography. If so, it should be stated that the ε-like wave is in a horizontal position. Dr. Fontaine considered the letter sequence D, E, G and H in the Greek alphabet. If the additional wave located at the beginning of QRS complex in ventricular pre-excitation is called a delta (δ) wave, the following additional wave in the Greek enumeration could be named according to the alphabetical sequence as an ε wave. Faced with this uncertainty, we decided to ask the author/creator of this nomenclature, Dr. Fontaine, who replied: “The naming of the EKG waves and the reason of their choice is a long story. Dr. Willis Hurst in Circulation published a summary of the naming of the Epsilon waves some years ago. I contributed to do this paper as indicated by Dr. Hurst."
Dr. Hurst wrote: “Fontaine discovered and named the ε waves. He chose the ε because it follows delta (δ) in the Greek alphabet and is the mathematical symbol for smallness.” The term "ε" was nice, because it occurs in the Greek alphabet after δ; thus, this letter represents the pre-excitation and ε the post-excitation phenomenon. In addition, ε is also used in mathematics to express a very small phenomenon. Late potentials (LPs) located on the free wall of the RV of patients with AC could be recorded on the body surface by signal-averaged ECG (SAECG) and in some circumstances by increasing the magnification of the standard EKG recording.
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