Late potentials

Late potentials are thought to be caused by early afterdepolarizations of cells in the right ventricle (in ARVD). Their amplitude is often too small to show up on a normal ECG. However, when multiple QRS recordings (typically 250 consecutive QRS complexes) are averaged, random noise is filtered out and late potentials can show up. Such a recording is called a Signal Averaged ECG (SAECG). The ARVD taskforce has published a document with recommended settings to record an SAECG in ARVD.

Criteria for late potentials on a signal averaged ECG [1][2]
filtered QRS duration > 114ms terminal (last 40ms) QRS root means square (RMS) voltage < 20 µV low amplitude (<40 µV) signal (LAS) duration > 38ms Noise should be minimal with a standard deviation of the TP segment of < 1 µV

References

1. Simson MB. Use of signals in the terminal QRS complex to identify patients with ventricular tachycardia after myocardial infarction. Circulation. 1981 Aug;64(2):235-42. DOI:10.1161/01.cir.64.2.235 |
2. Breithardt G, Cain ME, el-Sherif N, Flowers NC, Hombach V, Janse M, Simson MB, and Steinbeck G. Standards for analysis of ventricular late potentials using high-resolution or signal-averaged electrocardiography: a statement by a task force committee of the European Society of Cardiology, the American Heart Association, and the American College of Cardiology. J Am Coll Cardiol. 1991 Apr;17(5):999-1006. DOI:10.1016/0735-1097(91)90822-q |