Differentiating SVE from VE

There are two pearls to observe:
1. See if there are any non-aberrant ectopics and count the number of big squares between the R waves - this tells you the coupling interval length that will NOT impinge upon the refractory period of the bundle (usually the right bundle).
2. See if the T wave before the ectopic is different to all other T waves (it will usually be HIGHER).