Pathologic observation on ventricu lar myocardium of epicardium and focus underneath atrioventricularring produced by microwave catheter ablation / 中国地方病学杂志

ABSTRACT

Objective To observe the variation of enzymatic activity and areas and bulk of focus of heart injuries by using controllable catheter to ablate epicardial tmsue of rabbits and focus underneath atrioventrieular ring narcosis with 20% urethane(4 ml/kg)and divided into three groups.Each group included 7 rabbits.Anterior wallepieardium of left ventricle was ablated thirty seconds in each group(10,20 and 30 W)with self-made ablationspheroid microwave antenna,refilling with high pressure normal saline at same time.Then all of the rabbits were sacrificed respectively and their ventricular myocardium were taken out to undergo immunohistochemistry in order to display suceinate dehydrogenase(SDH).Also amplitude Wag measured in order to calculate areas of heart injuries.(8F)wag delivered to the pre-selected sites around atrioventricular ring of thirty-two healthy dogs,which had beenin intravenous narcosis with pentobarbital sodium(30 mg/kg).The dogs were divided into four groups(40,50,60 and 80 w) and two time points(60 and 120 s),by the combined method of X-ray and endocardial electrocardiograph,the microwave antenna could be confirmed to be located at the accurate position between anterior and posterior wall close to septum of left/right ventricle.After ventricular myocardium had been taken out,amplitude were measuredin order to calculate bulk of heart injuries by 1/6×3.14 x long×wide×deep.In addition.the histological changesand transmural injury were examined by optic microscope.Results In each group,the centre of injuries wagenzyme deficiency locus.The diameter and areag of heart injuries enlarged significantly(3.99.±0.41),(5.20±0.25),(6.31±0.37)mm and(12.53±2.56),(21.19±3.14),(30.96±3.76)mm2 with the increased microwave power level(10、20、30 W).Group comparison had statisficM significance(F＝76.8,58.5;P＜0.01 or ＜0.05).A total of 116points were ablated.The myocardial lesion showed ellipse in shape,and continuous symmetrical coagulationnecrosis under microscopic examination.There was a clear demarcated line around tlle myocardial tissue and fewparietal thmmbus.There were 16 transmura]injuries and five-with lung damage.The bulk of lesion aroundatrioventrieular ring hag been significantly enlarged(46.7±2.5),(51.1±2.7),(133.2±3.4),(141.8±3.9),(248.5±6.2),(260.3±6.5),(313.7±9.5),(327.4±10.5)with the increased microwave power level(40,50,60and 80 W)and/or distance of microwave ablation(60 and 120 s).Groups comparison had statistical significance(F＝31.16,27.85;all P＜0.01).In each time point,the lesion bulks had conspicuous distinction of statistics.In the same microwave power,the time wag longer,the bulk was larger(P＜0.01).Conclusions The more the microwave power level and time,the severe the heart injuries is.It is possible to use the microwave energy to ablate the deep focus under endocardium around atrioventricular ring.