RADIOFREQUENCY CATHETER ABLATION OF VENTR ICULAR TACHYCARDIAS LATE AFTER MYOCARDIAL-INFARCTION

Radiofrequency catheter ablation has recently emerged as a therapeutic option for ventricular tachycardia in postinfarction patients. Howeve r, the indications for its use and the mapping procedure remain contro versial. The most common arrhythmogenic circuit found fits an ''8'' sh ape model. This model incorporates a slow conducting central area, sep arated from the surrounding myocardium by conduction blocking areas an d with entrance and exit sites. This circuit has classically been conf ined in the left ventricle. However, recently successful radiofrequenc y catheter ablation of ventricular tachycardia has been reported from the right ventricle. Several markers for adequate positioning of the a blation catheter have been reported: local presystolic activity, isola ted middiastolic potential, transient entrainment with concealed fusio n, match between electrogram-QRS and stimulus-QRS intervals, match bet ween first postpacing interval and tachycardia cycle length and tachyc ardia electrocardiographic reproduction by pace-mapping. Procedure rel ated complications are rare and the success rate is around 70%. Nevert heless, currently this technique should be Limited to postinfarction p atients with ventricular tachycardia meeting certain requisites.