Isorhythmic AV dissociation

Figure 1 - Long lead II and V1

What is the rhythm?

This is regular narrow QRS complex rhythm (~88  bpm). Most would call this accelerated junctional rhythm.

Figure 2 - Full disclosure with P waves marked

P waves are marked in red arrows. They are upright in II and negative in aVR. This means that there still sinus rhythm. However, the ventricles is controlled by the junction. There is AV dissociation. When the atria and ventricles are dissociated and the rates are the same, this is called isorhythmic AV dissociation. 

Figure 3 - Follow-up strip 

Follow-up strip shows the separation and merging of the P and the QRS.

These are strips (static mode)  are difficult to interpret or often misled an interpreter. Longer strips like reviewing them on telemetry will make the interpretation easier. 

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