Here is a rhythm strip from a 3-lead Holter ECG. It comes from a 56-year-old man with arterial hypertension and no other previous cardiac diseases. Recently, the patient has noticed that pulse irregularities occur during blood pressure measurement (which he performs himself at home).
On the ECG, first a sinus beat, then a PVC, then an AIVR occurs, which is interrupted by another PVC, then sinus rhythm again.

AV blocks are among the ECGs that are particularly difficult to diagnose and where the most mistakes are made.
Here is the ECG of a 75-year-old lady who has not been feeling well for the last few weeks and is complaining of shortness of breath on exertion.
The ECG is irregular with alternating smaller and larger RR intervals.
QRS 2, 4 and 6 each show the same PR interval; it can be assumed that these are sinus node beats that are conducted.
QRS 1, 3, 5, 7 are junctional escape beats without reference to the P waves.

What can we learn from this 3-channel ECG?
A sinus rhythm can be seen in the left half of the image, which merges into a ventricular tachycardia on the right. The QRS complexes of the VT change their shape and polarity, this is called polymorphic.
The question is: can this be called TdP (Torsade de Pointes) tachycardia or not? The clear answer is: no! A polymorphic VT may only be called TdP if there is a prolonged QT/QTc duration in the native rhythm. This is obviously not the case here. Therefore, the term polymorphic VT is retained here

This ECG (3 rhythm strips) initially shows a sinus rhythm with 1st degree AVB grade I and wide QRS complexes (presumably RBBB pattern). A PAC (P-wave premature, different form than in sinus rhythm) appears approximately in the middle of the ECG, this is not conducted . Due to the strong prematurity, this is not surprising. But why is the 2nd PAC also blocked? The answer can be found in the second picture.