A Unifying explanation

This is referred to you because of bradycardia. What is the cause of the bradycardia in this ecg?

Figure 1

The seemingly bradycardic episodes are due to non-conducted premature atrial complexes or PAC's (best seen in V2 marked with red arrows) but difficult to see in the rest of the leads. Beats #3 and #5 looked like junctional beats because the P waves looked inverted in lead II. However, in most arrhythmias, there is a unifying explanation for the whole behavior. In this case beats #3 and #5 are PAC's that are conducted (# 3 is conducted normally and #5 is conducted with aberrancy). Thus, the periods of bradycardia are due to nonconducted PAC's.

Figure 2



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  2. An interesting ECG with very reasonable interpretation, Dr. Arnel Carmona. But I saw that the morphology of beat #5 is not typical for RBBB or LBBB aberrancy. So, Is there any possibility that beat # 5 is a VPC?