Left ventricular catheter ablation using direct, intramural ethanol injection in swine.

INTRODUCTION: Limitations in lesion volume and particularly lesion depth may negatively effect the efficacy of catheter ablation procedures using radiofrequency energy. This study evaluated the safety and efficacy of myocardial ablation using direct intramural injection of ethanol with a novel injection catheter system. METHODS: Left ventricular lesions were performed in 9 male swine (80-85 pounds); two animals were studied 6 weeks following anterior infarction produced by agarose gel embolization. An 8 Fr deflectable catheter equipped with a 27 gauge adjustable depth, retractable needle was directed to the LV using a retrograde aortic approach. Lesion deployment was guided by fluoroscopy and intracardiac echocardiography (ICE). Lesion characteristics were assessed with ICE imaging and pathologic analysis. RESULTS: Ethanol lesions were confined to the tissue directly adjacent to the injection port. Lesions were intramural with no evidence of overlying thrombus. Lesions delivered with a single port injection needle in normal myocardium (n = 24) averaged 1910 +/- 1066 mm(3) with a depth of 8.9 +/- 3.3 mm. Lesions directed to infarct border zones (n = 4) averaged 929 +/- 882 mm(3) with a depth of 4.3 +/- 2.8 mm. Lesions were immediately evident on ICE imaging, and were visualized by increased echo density and tissue swelling. Pathological analysis revealed homogenous lesions with intramural hemorrhage and contraction band necrosis. CONCLUSIONS: Myocardial catheter ablation using direct ethanol injection is feasible, and relatively large and deep intramural lesions can be delivered, even in the infarct border zone. This technique may prove useful in ablation of arrhythmia substrates that are deep to the endocardial surface.