We have tachycardia…
The patient has been determined to have AVNRT and a slow pathway ablation is being performed.
This 3D image is in an RAO projection with a cutaway to see the internal aspect of the right atrium.
Which of the following would you suggest as a slow pathway target?
- Site 1
- Site 2
- Site 3
- Site 4
- Site 5
Answer:
Site 5 is the location of the slow pathway. This is the area that we target for AVNRT.
Notice the ablation lesions marked with red.
How to we determine success?
RF ablation was performed at the site displayed above.
The location showed a small fractioned atrial signal and a ventricular signal. The size of the V:A was approximately 3:1.
This electrogram was recorded during ablation.
What do you observe?
Are we successful?
Answer:
Ablation should be immediately terminated due to the observed heart block. This demonstates ablation of the fast (normal) pathway. If ablation were to continue the patient may be in need of a permanent pacemaker.
Every atrial signal should be followed with a ventricular signal.
This example is a little trickier since the first two beats are junctional rhythm you are unable to observe the normal PR interval. Some physicians perfer to pace the atrium if junctional rhythm is observed in order to better monitor for heart block.
What to do?
After reposistioning the catheter, the following was recorded during another ablation attempt.
What are your thoughts?
Answer:
This is a slow junctional rhythm which will be observed with a successful slow pathway ablation. However, just because junctional rhythm is seen, success is not guaranteed, further ablation may be needed.
Whatever testing measure that were performed prior to ablation which demonstrated dual nodal physiology (2 inputs to the AV node / AVNRT) should be repeated. If Isuprel was used to induce AVNRT prior to ablation, then it is recommended to use it during post testing as well.
