Characteristics of myocardial tissue staining and lesion creation with an infusion-needle ablation catheter for the treatment of ventricular tachycardia in humans

Intramural substrate causing ventricular tachycardia can be targeted by radiofrequency (RF) infusion-needle catheter ablation. The purpose of the study was to assess fluid distribution within the myocardium after needle-ablation catheter infusion and its evidence to RF lesion creation. In 25 patients (21 (84%) male; 67 ± 9 years; 8 (32%) with ischemic cardiomyopathy) intramural ablation of ventricular tachycardia was performed with a needle catheter. Fluoroscopic images of myocardial staining patterns produced by pre-RF saline/contrast infusion were analyzed. Lesion creation was defined as tissue inexcitability to high-output needle pacing. Data from 155 sites were eligible for analysis. Tissue staining was evident in 111 (72%) and absent in 44 (28%). The stain shapes were variable, with average dimensions of 20 ± 10 × 8 ± 4 mm with an area of 68 ± 58 mm2. Round/oval-shaped stains were most common (62 [56%]), while multisegmented (36 [32%]) and long flat (13 [12%]) configurations were less frequent. Evidence of staining was associated with evidence of lesion creation (92/111 (83%) vs 17/44 (39%); P ≤ .0001). Contrast staining around the needle was present in 50%, usually had blurred margins, and was associated with lesion creation. When staining extended well beyond the needle, the margins were often sharp, suggesting dissection through tissue planes, and lesion creation tended to be less effective. With infusion-needle ablation, preablation injection of contrast can help confirm an intramural position and predict lesion creation. Tissue diffusion patterns vary markedly, and studies to assess its relation to tissue architecture and ablation lesion geometry warrants further investigation. The findings also have implications for the injection of therapeutic agents into the regions of scar.