This page shows a collection of interesting ECGs. These are often examples of rare diagnoses, which is therefore given.
Junctional Ectopic Tachycardia (JEt). Lead II shows how the nodal rhythm and sinus tachycardia compete. Around the third beat the sinus rhythm is conducted during the next couple of beats. Thereafter the nodal rhyhtm takes over and around the 8th beat a negative p-wave develops, the ultimate proof of the junctional origin of this rhythm.