Atrial Dissociation in Transplantation

What is your ECG  interpretation?

 

Figure 1 - ECG case in full disclosure

 

 

Figure 2 - P waves marked

 

This is a regular wide QRS complex tachycardia at a rate of about 130's bpm with a right bundle branch block morphology.

 

There are 2 sets of P waves that can be appreciated. The first p wave morphology (red arrows) has a cycle of about of 440 ms or at 136 bpm. The second P wave morphology (blue arrows) has a cycle of about 560 ms or at 107 bpm. The second P wave morphology is sometimes hidden from view or are buried in the QRS (black arrows). Occasionally, fusion of the P waves can be seen (green arrows and F). Both P waves are inverted in aVR.  The two P waves are dissociated. So, we have atrial dissociation with the other P wave conducted with 1:1 ratio with a RBBB morphology.

This ECG is a from a post-cardiac transplant patient. Two sets of P waves frequently results from a procedure that sutures the donor heart to the corresponding structures of the recipient residual atria. The 2 sets of P waves are usually dissociated from each other but in some cases becomes synchronized. Unusual atrial rhythms also develop particularly when one of the sets of the 2 atrial components develops ectopic activity, atrial fibrillation or atrial flutter. A complete or incomplete RBB is present in more than 80% of ECGs after transplantation.

 

Reference:

 

Surawicz B and Knilans TK. 2008. Chou’s Electrocardiography in Clinical Practice. 6th ed. PA. Saunders-Elseiver

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