Final answer:
The 2nd degree Mobitz II AV block is characterized by intermittent conduction failures between the atria and ventricles, resulting in P waves without a subsequent QRS complex on an ECG.
Step-by-step explanation:
The 2nd degree Mobitz II AV block is characterized by intermittent conduction failures between the atria and ventricles. On an ECG, it is recognized by the presence of P waves without a subsequent QRS complex.
An example of this can be seen in Figure 19.25 of the reference material provided. In this type of block, some of the electrical signals from the SA node reach the AV node but fail to be conducted to the ventricles, resulting in dropped QRS complexes.