The Experimental Study On Treating Obstructive Hypertrophic Cardiomyopathy Using Laser Ablation And The Echocardiographic Evaluation Of The Surgical Effect

Part1 Laser Ablation of Normal Sheep Interventricular septum of isolated heartObjective: To study the range and characteristics of laser ablation(LA)of isolated sheep ventricular septum with different power and time,and to understand the ablation characteristics of laser in myocardial tissue,so as to provide reference for in vivo animal experimental ablation and future clinical application.Methods : The 27 fresh isolated IVS of sheep were respectively divided into 3 groups according to 2W,3W and 4W.Each group was respectively divided into 3 groups according to 500 J,1000J and 1500 J.After the laser ablation,the myocardial tissue was cut open along the needle tract.Results: The ablation area of myocardial tissue was gray-white at 2W.The carbonization area and gasification cavity were not observed.The ablation of myocardial tissue were focus from the inside out,coagulation necrotic area and hyperemia reaction area.Carbonization and gasification cavities can be seen in the center of other groups.With the increase of energy,the area of carbonization and gasification cavity were increased.The ablation focus was from the inside out.Ablation area of LA group was composed of gasification cavity area,carbonization area,coagulation necrosis area and hyperemia reaction area.There was statistically significant of the volume between 2W and 3W with 1000 J.There was statistically significant between 500 J,1000J,and 1500 J groups with 3W.Conclusion: There are different ablation range with different ablation energy of LA and carbonization in ablation center.It can provide reference for choosing appropriate LA energy for myocardium in animal experiment.Part 2 Echocardiography Guided transthoracic Percutaneous Laser Ablation of the Interventricular SeptumObjective: To investigate the long-term efficacy of ultrasound-guided transthoracic laser ablation of ventricular septum(TPLA)in the treatment of HOCM,and to evaluate the efficacy and safety of TPLA in ablation of ventricular septum in healthy sheep models.Methods:Twelve healthy adult sheep were randomly categorized into two groups: with and without the laser application of TPLA of the interventricular septum(IVS)at the energy level of 5W1000 J.Echocardiography,electrocardiography(ECG),cardiac magnetic resonance(CMR)and serological and pathological examinations were performed over a 12-month follow-up.Results:After the laser ablation all animals survived with normal cardiac function;No severe complications or bundle branch block were noted.The thickness(8.40±0.45 vs3.11±1.14 mm,p < 0.05)and regional movement of ablated IVS decreased between the experimental and control groups.The Troponin I level was significantly elevated after the operation,which validated immediate cardiac coagulation necrosis.On cardiac magnetic resonance(CMR)imaging,the ablated myocardium showed significant fibrosis evidenced by late gadolinium enhancement.Pathological results revealed damaged ultrastructure of the ablated myocardium and development of fibrosis in the long term.Conclusions:TPLA is a safe and effective,minimally,invasive method to reduce IVS thickness in the long term,making it a potential alternative for HOCM treatment.Part 3 Assessment of left ventricular global systolic strain in hypertrophic ardiomyopathy after surgery by two-dimensional speckle tracking imagingObjective: To evaluate left ventricle systolic function in patients with obstructive hypertrophic cardiomyopathy(HOCM)after modified Morrow surgery was evaluated using two-dimensional speckle tracking imaging(2 D-STI).Methods : Twenty three HOCM patients were recruited in this study.Echocardiographic data were analyzed using Q lab software to compare the variation in systolic function pre-and 1-month and 3-month post-operation including global and 16 segmental longitudinal strain,circumferential strain and conventional echocardiographic parameters of left ventricle.Results: Compared with preoperative data of HOCM patients,postoperative LVOT diameter and pressure gradient,left atrial diameter and volume index were significantly decreased.There was no statistically significant difference in left ventricular ejection fraction.Compared with the preoperative case,global and segmental longitudinal strain shows no significant variation.However,the circumferential strain reduced significantly.Conclusions: Two-dimensional speckle tracking technology can effectively evaluate global and regional systolic function of left ventricle for HOCM patients after modified Morrow surgery.