| Background:Hypertrophic cardiomyopathy(HCM)is an autosomal dominant myocardial sarcomere,and the incidence of the disease in the global population can be as high as 1/500.Clinically,HCM is divided into two common types according to the changes in hemodynamics of the disease,namely hypertrophic non-obst ructive cardiomyopathy and hypertrophic obstructive cardiomyopathy(HOCM),among them with left ventricular outflow tract obstruction?(LVOTO)of hypertrophic cardiomyopathy is called hypertrophic obstructive cardiomyopathy,which mainly has fixed stenosis due to hypertrophy at the base of the interventricular septum,causing obstruction of the left ventricular outflow tract(accounting for up to 70%of patients),leading to heart failure with breathing difficulties,chest pain,atrial fibrillation and sudden death.Therefore,most treatment strategies aim to enlarge LVOT and reduce LVOT obstruction.For patients with drug resistance and surgical-intolerance,considering the risks of ventricular alcohol ablation and various serious complications caused by transcatheter radiofrequency ablation,it is necessary to develop and try new minimally invasive methods.Liwen liu created a new way of treatment that "Liwen operation" percutaneous intramyocardial septal radiofrequency ablation and percutaneous intramyocardial septal laser ablation.The former has been applied in clinical preliminary trials and has a significant effect;the latter is still in the exploratory stage of animal experiments.Therefore,This study will refer to the two minimally invasive ablation methods of liu's team and adjust to the conditions suitable for experimental dogs,to explore the differences of transthoracic echocardiography-guided percutaneous ventricular septal ablation(laser ablation,radiofrequency ablation),so as to provide a reference for further clinical minimally invasive ablation.Object:The purpose of this study was to compare the differences between percutaneous intraventricular septal laser ablation and radiofrequency ablation in order to better adapt to the clinical needs.Methods:The experimental animals were 10 adult beagles(all healthy,male or female).According to the body weight random number 1-10,they were randomly divided into group laser ablation and group radiofrequency ablation,with five in each group.The basal and middle segments of the ventricular septum were ablated in each dog.Group laser ablation adopted laser ablation method:the power of the base segment is 1W for 180s and the power of the middle segment is 1W for 300s;Group radiofrequency ablation adopted radiofrequency ablati on:the base segment power is 15 W for 45 S,and the middle segment power is 25W for 45S.Routine ultrasound,myocardial contrast-enhanced ultrasound and serological examination were performed before,immediately after,1 week and 1 month after surgery,cardiac enhanced CT was performed 1 week and 1 month after surgery.One month after the surgery,all the experimental dogs were sacrificed and their hearts were dissected to evaluate the ablation range.Results:There were no significant changes in living habits and other serious complications(ventricular septum perforation,pneumothorax,pericardial tamponade,a trioventricular block,ventricular fibrillation,etc.),and no significant changes in ecg.The change trend of ultrasonic parameters of experimental dogs in the two groups was the same after ablation.The inner diameter of LVOT of experimental dogs in the two groups increased immediately after ablation compared with that before surgery,decreased 1 week after surgery compared with that before surgery,and increased 1 month after surgery compared with that before surgery(P<0.05).Immediately after the operation,the diastolic interventricular thickness of the two groups of experimental dogs was thicker than that before the operation,and the difference was not statistically significant one week af ter the operation compared with that before the operation,while the thickness was thinner in one month compared with that before the operation(P<0.05).The EF value of the two groups decreased immediately after the operation compared with that before the operation(P<0.01),and there was no significant difference in the one week and one month after the operation compared with the preoperative value;The peak LVOT gradient of the two groups of experimental dogs decreased immediately after surgery(P<0.01),and increased 1 week after surgery(P<0.01).The value of forward mitral valve velocity E/A in the two groups decreased immediately after surgery and 1 week after surgery(P<0.01),and there was no significant difference at 1 month after surgery.The E'/A' value of the movement velocity of mitral annulus in the doppler spectrum of the two groups of experimental dogs decreased immediately after the operation and one week and one month after the ablation(P<0.05).The motion amplitude of ventricular septum(base,middle)in both groups decreased immediately after surgery,one week after surgery and one month after surgery(P<0.01),while the motion amplitude of left ventricular posterior wall in both groups increased immediately after surgery,one week after surgery and one month after surgery(base,middle)(P<0.05).The values of myocardial enzymes(CK,CK-MB,LDH)in both groups in creased significantly immediately after surgery compared with before surgery(P<0.05).Range of cardiac enhanced CT ablation lesions in laser and radiofrequency ablation one week and one month after the experiment:the ablation site volume of 1W300s in the laser group was greater than 1W180s(P<0.05).The ablation site volume of 25W45s in the radiofrequency group was greater than 15 W45s(P<0.05).The ablation site volume of radiofrequency group was larger than that of laser group(P<0.01).The range of ablation lesions in the heart of experimental dogs:the ablation site 1W300s in the laser group had a transverse diameter,a longer diameter,and a volume greater than 1W180s(P<0.05);compared with 25W45s and 15W45s in the radiofrequency group,only the volume increased(P<0.05);The lateral diameter,long diameter,and volume of the ablation focus in the laser group were shorter than those in the radio frequency group(P<0.01),and the ablation time was longer than that in the radiofrequency group(P<0.01).Conclusion:1.Both laser and radiofrequency ablation can damage ventricular septum myocardium to different degrees,and they are of high safety and feasibility.2.By comparison of the two methods,the puncture time and ablation time of the laser group were longer than that of the radiofrequency group,and the ablation range was larger than that of the laser group,while the coagulation necrosis range of the laser group was more accurate.3.Two-dimensional ultrasound is of great value in the selection of injection path,real-time monitoring of ablation range,dynamic observation of ventricular septum and changes in overall cardiac function during ablation.4.Myocardial contrast-enhanced ultrasound and enhanced CT play an important role in real-time,convenient and objective evaluation of ablation range and ablation effect in the immediate postoperative and postoperative follow-up. |
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