Cor Vasa 2002, 43(2):62-71

Electroanatomical 3D mapping of the arrhythmogenic substrate and catheter- -based radiofrequency ablation of ventricular tachycardia using cooled catheters in patients after myocardial infarction-a pilot study

Petr Neužil^1,*, Miloš Táborský¹, Vivek Reddy³, Lucie Šedivá¹, Roman Vopálka², Jan Petrů¹, Petr Niederle¹

¹ Kardiologické oddělení

² Oddělení zdravotnické techniky, Nemocnice Na Homolce, Praha, Česká republika

³ Cardiac Arrhythmia Service, Massachusetts General Hospital, Boston, Massachusetts, USA

Introduction:
Ventricular tachycardia (VT) developing secondary to an ischemic arrhythmogenic substrate poses a substantial hemodynamic threat to most patients. Their morphology is multiple making "clinical tachycardia" difficult to define. As a result, the established and otherwise very effective mapping criteria applicable to an ongoing VT induced during an electrophysiological testing procedure often cannot be used.

Method:
The present study reports on the clinical use of electroanatomical three-dimensional (3D) mapping using a CARTOTM system involving the reconstruction of individual left ventricular maps (bipolar and unipolar potential maps, and a map of intraventricular electrocardiogram duration) and their use in navigating the creation of linear radiofrequency (RF) lesions in unstable forms of VT using "cooled" catheters. High-density electroanatomical 3D mapping with the CARTOTM system was performed in spontaneous sinus rhythm or with stimulation from the right ventricular apex in a total of 18 patients after myocardial infarction (MI) and hemodynamically unstable VT (an average 3.3 ± 1.7 VTs per patient were induced).

Results:
A post-MI scar with its marginal zone was demonstrated in 17 (94%) of these patients. In all patients, we were able to construct all three above maps (bipolar voltage, unipolar voltage, and electrocardiogram duration maps). In the last 11 consecutive patients, catheter-based radiofrequency ablation (RFA) using linear lesions was also performed. The lesions were created using "cooled" ablation catheters with open saline rinse. To improve the accuracy of navigation in creating RF linear lesions, stimulation mapping was used to provide guidance regarding the potential sites of output from the ventricular reentry isthmus in the visualized marginal zones of the infarction scar. An average 33 RF lesions (range, 11 to 83) were produced. We sought to create at least two perpendicular lines of RF lesions crossing the critical sites of marginal zones of the purported sites of origin of the documented VT, with the resulting average number of 3.4 lines of RF lesions per patient. After the procedure, the effect of the procedure was tested using programmed ventricular stimulation (right ventricular
/RV/ apex and outflow tract, left ventricle /LV/). Complete and partial VT elimination was obtained in 7 and 2 patients, respectively (i. e., in a total of 82% of patients).

Conclusion:
Using substrate mapping and identification of potential arrhythmogenic tissue, the CARTOTM system is effective in creating, by means of cooled catheters, navigated linear RF ablation lesions in sinus rhythm. This minimally invasive method is convenient to the patient and is expected to find use in complete linear ablation of the arrhythmogenic substrate.

Keywords: Monomorphous ventricular tachycardia; Electroanatomical mapping of the arrhythmogenic substrate; Linear radiofrequency catheter-based ablation

Published: February 1, 2002  Show citation