Visualizing complex cardiac arrhythmias.

A nonfluoroscopic, catheter-based, three-dimensional electroanatomical mapping system (CARTO system, Biosense-Webster, Diamond Bar, CA, USA) has been developed that may aid in ablating complex cardiac tachyarrhythmias. The system uses magnetic technology to accurately determine the three-dimensional location of the mapping and ablation catheter. Recorded data of the catheter location and an intracardiac electrogram (ECG) at that location are used to reconstruct a real-time representation of the three-dimensional geometry of the chamber, color-coded with relevant electrophysiological information. The sequence of activation is visualized on the reconstructed geometry of the cardiac chambers by the colors of the spectrum (red, orange, yellow, green, light blue, dark blue, and purple). With this system, the activation pattern and the target site for ablating complex tachyarrhythmia can be visually demonstrated. Since the deployment of this system, we have cured a total of 168 cases of various complex tachyarrhythmias. Two representative cases are shown in the figures. In a 17-year-old teenaged boy with exercise-induced atrial tachycardia (Fig. 1), the activation map exhibited a radially spreading pattern from a focus in the posterior wall of the left atrium. The radiofrequency ablation at the earliest activation site