If there is a blockage between the av node and the av bundle, how will this affect the appearance of the electrocardiogram?

Out of the following given choices;

A. PR interval would be smaller

B. QRS interval would be shorter

C. There would be more P waves than QRS complexes

D. There would be more QRS complexes than P waves

E. The T wave would be absent

The answer is C. Waves on the ECG represent the depolarization an repolarization of the atrial and ventricular walls. The sequence of waves on the ECG is P waves, QRS complex, then T waves. Therefore, If there is a blockage between the av node and the av bundle, P waves of atrial contraction are of longer intervals (more than 200 ms) compared to those of QRS complex of ventricular contraction. This is referred to as the First Degree Heart Block. In second-degree heart block, no QRS complex follows the P waves