How to quickly and safely isolate PVs?

• how to isolate PVs
• whats pace-and-ablate technique
• what signals need to be ablated

Pulmonary vein isolation (PVI) is an anatomic procedure and it will be mostly guided by the imaging. Nevertheless, paying attention to signals is always advisable. In contrast to most of the ablations procedure the target is not a described source of arrhythmia but the muscle bundles surrounding the pulmonary veins. The goal of the procedure is to ensure complete line of block around those structures. It is essential to understand that the smallest gap in isolation line will undermine the success of the procedure.  Here are some tips and tricks how to be sure you don’t miss anything:
 

• Lesions visualization: modern mapping systems provide you with the guidance not only when it comes to anatomy of the heart chamber and catheter movement but also regarding the lesion formation and its quality. For successful lesion formation some given amount of energy must be delivered to the tissue and this can be calculated from the energy setting of the catheter, contact and catheter stability. Mapping system will color-code it and provide you with visualization of durable and less durable lesion. In order to have a good line you need to have closely spaced single lesions of good quality. You can easily detect the bad spots by inspecting the lesion markers you have achieved. Note that different platforms have different specifications for good and bad lesions and you need to get this information from your technical support or make your own judgment.
• Signal characteristics: as in case of any ablation you should pay attention to what the signals are telling you. If you carefully inspect the line of isolation that you have previously conducted and you find sharp, high amplitude signals, you have probably found a spot still requiring ablation. You can confirm that this region is still conducting by using pacing from ablation catheter. If you have capture, you should probably ablate some more but be sure you are still on the lesion line or just a bit within it. This approached can be called pace-and-ablate.
  Pace-and-ablate technique: using capture of a paced impulse as an indicator of lesion quality is commonly known as pace-and-ablate technique. It is quite straight forward. You pace with a CL shorter than SR (e.g. 500-600ms) via ablations catheter and look for a capturing of atrium. If you find such a spot you perform additional ablation. You can keep pacing till loss of capture is reached or switch of the pacing off and on for verification. Don’t be fooled by absence of capture caused by lack of contact with the tissue. In order to exclude this frequent source of error pay attention to contact forced indicated by catheter sensor. Other option is to zigzag the ablation line by pulling the catheter a little bit outside the ablation line where a capture should be present. If you missing capture in non-ablated region you probably miss contact.In general, this technique is especially useful at the end of drawing the ablation line or for detecting a gap in it. If you try it just from the start you will continuously capture veins and atrium at quite high rate which will result in induction of AF.