From the ECG vault

What is your interpretation?

Image 1

This is an irregular rhythm with no P to QRS relationship. The QRS duration is about 0.10 sec as measured using aVR. 

Lead I is predominantly positive and aVF is predominantly negative  or there is left axis deviation. There is qR pattern  in aVL and there is rS pattern in II, III and aVF. This QRS morphology suggest left anterior fascicular block (LAFB).

Image 2

As to the P waves, there is a bigeminal pattern. Bigeminal pattern P waves can be seen in PAC in bigeminy or sinoatrial block. 

Without R3 and R7, the pattern is of complete heart block (CHB) with a junctional escape with LAFB. R3 and R7 could  be premature junctional beats conducted with LAFB. R3 and R7 cannot be PAC's because supraventiruclar impulse cannot be conducted in CHB.

So, this is sinus rhythm with bigeminal pattern probably sinoatrial block, complete heart block with junctional escape conducted  with LAFB and premature junctional complexes.

* If you have another probable explanation, feel free to post. As seasoned ECG reader would say, an ECG can have multiple possible explanations.