Intracoronary ethanol ablation in swine: characterization of myocardial injury in target and remote vascular beds.

INTRODUCTION

Physical or chemical ablation of arrhythmogenic tissue has been shown to be an effective modality of arrhythmia therapy. Chemical ablation by intracoronary infusion of ethanol into a specific coronary artery bed has been demonstrated, but the characteristics and distribution of necrosis relative to the coronary blood supply have not been delineated.

METHODS AND RESULTS

A total of 40 myocardial lesions were created in 21 pigs by infusion of 1.6 +/- 0.6 mL of 50% ethanol and 50% iohexol contrast solution through a 2.7 French infusion catheter advanced into a branch of the left anterior descending or circumflex coronary artery. Prior to ethanol infusion, 5.3 +/- 1.2 mCi technetium-99m (Tc-99m) methoxyisobutyl isonitrile (sestamibi) was infused into the coronary branch in order to delineate the perfusion bed. After completion of the lesions, each heart was removed, sliced transversely in 5-mm slices, and stained with nitro blue tetrazolium in order to define the ablation bed. The slices were then imaged with a gamma camera and the area of Tc-99m sestamibi uptake was defined as the perfusion bed. These respective areas were planimetered for each slice and compared. No difference was observed in hemodynamic parameters between preablation and postablation measures except mean arterial pressure, which fell from 122 +/- 22 mmHg to 116 +/- 24 mmHg (P = 0.02). Significant ventricular arrhythmias were observed after 60% of the ablations. The mean left ventricular ejection fraction fell from 55% +/- 9% to 45% +/- 15% after completion of all ablations. The areas of the ablation beds were related to the areas of the perfusion beds but the correlation was poor (r = 0.41, P = 0.0001). Generally, the ablation bed was smaller than the perfusion bed, but evidence of ethanol reflux was observed in 29% of the lesions resulting in injury beyond the targeted perfusion bed.

CONCLUSIONS

Intracoronary ethanol ablation is a promising technique for the treatment of arrhythmias. Significant arrhythmias and a decrease in left ventricular ejection fraction are associated with this technique. Lesions are generally produced within the distribution of the targeted coronary bed, but are also frequently associated with reflux to a second vascular distribution.