TRANSCATHETER SUBENDOCARDIAL INFUSION - A NOVEL TECHNIQUE FOR MAPPINGAND ABLATION OF VENTRICULAR MYOCARDIUM

Background Catheter ablation with radiofrequency energy is feasible in a limited subset of patients with ventricular tachycardia. The purpos e of this study was to evaluate a technique for mapping and ablation o f ventricular myocardium with the use of transcatheter subendocardial infusion. Methods and Results A needle-tipped deflectable electrode ca theter was used to deliver reagents to endocardial target sites. This was equipped with two central lumens to allow sequential administratio n of mapping and ablation injectants with minimal admixture. The mappi ng injectant consisted of a mixture of lidocaine, iohexal, and glyceri n; the ablation injectant contained ethanol, iohexal, and glycerin. In fusion of the mapping injectant (1 cm(3) over 3 or 5 seconds, n = 14) produced a stain on fluoroscopy and increased local capture threshold by 61%. No lesions resulted from mapping infusions. Infusion of the et hanol-containing injectant (n = 48) produced discrete lesions, with a mean volume ranging from 0.6 to 1.5 cm(3). There was a direct relation ship between infusion volume, infusion duration, and resultant lesion volume. Fibrosis in a region of healed myocardial infarction did not i mpair diffusion of the injectant or affect lesion dimensions. Microsco pic analysis of chronic lesions showed a sharply demarcated border zon e between fibrotic and normal myocardium. Conclusions Transcatheter su bendocardial infusion can be used to reversibly impair local excitabil ity and mark an injection site fluoroscopically. Subendocardial inject ion of ethanol can predictably ablate a large volume of ventricular my ocardium. Additional study of this system in an arrhythmia model will help to define its potential for mapping and ablation of hypotensive v entricular tachycardia.