Nonfluoroscopic three-dimensional mapping of the myocardium has been very helpful for isolating focal and nonfocal tachycardias. The technique is very similar to localization using the global positioning system. Using reference electrodes in the XYZ planes, one can identify the location of catheters and tachycardias within the heart. The catheters themselves or the surface electrodes can be used in setting the reference coordinates for mapping a tachycardia.
There are a variety of mapping systems commercially available. The most common are the Carto® 3 System (Biosense Webster, Inc., a Johnson & Johnson company) and the EnSite® Velocity™ System (St. Jude Medical). Other systems include the RhythmView™ Workstation (Topera, Inc./Abbott Laboratories) and Rhythmia™ Mapping System (Boston Scientific). These systems not only assist in the mapping of tachycardias, but may be useful in reducing radiation exposure during complex procedures. In fact, Sebastian Stec and colleagues used a “simplified, no X-ray” supraventricular tachycardia ablation procedure in 179 patients, and achieved a 98 percent acute success rate with a 93 percent long-term success rate and no major complications.