Ethanol Injection Ablation Of Ventricular Myocardium In A Swine Model: Lesion Morphology And Correlation Between Dose And Lesion Volume

Background Ethanol injection ablation is a potential option for treatment of ventricular arrhythmias with deep origin.However,the characteristics of ethanol ablation lesions have not yet been described.The purpose of this study was to investigate characteristics of ethanol ablation lesions induced by epicardial injection and correlation between lesion volume and ethanol injection doses.Methods In 6 hearts,freshly harvested from healthy swines(35-39 kg,9-12 months old),ethanol ablation was performed by injecting 10 sites on the free wall and apex of left ventricle of each heart,with different doses of ethanol.In the control group,2 doses of saline were injected.After injection,4 harvested hearts were visually inspected and measured by triphenyl tetrazolium chloride(TTC)staining,while the another 2 hearts were dealt with HE staining and TUNEL staining.The heart sections were stained with TTC to distinguish the range and shape of myocardial lesions.The volume of myocardium injury was calculated,and the correlation between different ethanol injection dose and myocardial necrosis volume was analyzed.The histomorphology changes of myocardium were observed by HE staining.TUNEL staining was applied to evaluate the apoptosis rate of myocardial cells.Results Lesion formation was visually observed at all sites of ethanol ablation and was absent at the sites that received saline injection.The morphology of ethanol ablation lesions appeared ellipsoid-like,either sectionally or spatially,along with myocardial fiber orientation.Compared with the control group,myocardial tissue displayed significant morphological changes under microscopy,such as karyopyknosis,karyorrhexis and nucleus disappearance in the ethanol ablation group.There was statistically difference in the apoptosis rate of myocardial cells between the 2 groups(84.99±2.87% in the ethanol group versus 4.56±3.36% in the control group,P<0.001).A significant positive correlation was observed between injury volume(mm3)and ethanol injection doses(ml)(y=864.14x-165.17(R2=0.93124,P<0.001).While injecting x(ml)of ethanol in the ventricular myocardium,the lesion depth(mm),lesion major diameter(mm),and lesion minor diameter(mm)would be estimated as 8x+3.4,6.2x+2.1,8.3x+5.6,respectively.Conclusion:Myocardial necrosis can be achieved with ethanol injection ablation.Our study found that the shape of myocardial lesions is ellipsoid-like,and lesion volume significantly correlated with administered dose of ethanol.