Nonsurgical Transthoracic Epicardial Electroanatomic Mapping And Radiofrequency Ablation Of Ventricular Tachycardia After Healed Myocardial Infarction

PartⅠEstablishment Of Chronic Myocardial InfarctionModel With Percutaneous Angioplasty Balloon OcclusionObjective: To investigate the feasibility and safety of establishmentof chronic myocardial infarction model with percutaneous angioplastyballoon occlusion.Methods: Twelve ZhongHua small pigs underwent the procedure toestablish chronic myocardial infarction model. The distal left anteriordescending of left coronary artery was occluded by percutaneousangioplasty balloon for 150 minutes, 12 lead electrocardiogram andmyocardial enzyme changes were observed during the procedure.Electrocardiogram and cardiac magnetic resonance imaging were performedin four weeks after the procedure in nine pigs that survived theprocedure. Finally the nine pigs were sacrificed and the pathologicalchanges were observed under light microscope.Results: Chronic myocardial infarction model was establishedsuccessfully in nine pigs that survived the procedure. Electrocardiogramshowed ST segment elevation, R waves reduction, T waves inversion,formation of pathological Q waves and so on. Myocardial enzyme such asCK, CK-MB, LDH, increased at 4 hours after occlusion of distal left anteriordescending. The location and range of mycocardial infarction were examinedby cadiac MRI, which was coincidence with the results of pathologicalobservation. Cardiac MRI also showed left ventricular enlargement, heartfunction reduction in the myocardial infarction model pigs. Transmuralmyocardial infarction was confirmed by light microscopy examination in all nine survival pigs.Conclusions: The percutaneous angioplasty balloon occlusion of distalleft anterior descending of left coronary artery is an effective methodto establish chronic myocardial infarction model.PartⅡNonsurgical Transthoracic EpicardialElectroanatomic Mapping Pigs after Healed MyocardialInfarctionObjective: To observe the feasibility of the nonsurgicaltransthoracic epicardial electroanatomic mapping pigs after healedmyocardial infarction and the effect of the magnetic resonance image(MRI)in the procedure.Methods: Three ZhongHua small pigs underwent the procedure toestablish chronic myocardial infarction model by percutaneousangioplasty balloon. After 4 weeks these three pigs and three normal pigsrecerved MRI examination. Six pigs underwent transthoracicpericardicentesis and five pigs accomplished the endocardial andepicardial bipolar voltage mapping of left ventricle.Results: The endocardial and epicardial bipolar voltage mapping ofleft ventricle were accomplished successfully in five pigs. One normal pigdied of ventricular fibrillation during pericardicentesis. 97.3% thebipolar electrogram amplitude of the normal pigs was＞0.5mV. The bipolarelectrogram amplitude of the myocardial infarction was＜0.5mV. Thereconstructed three-dimensional left ventricle of MRI matched the left ventricle of endocardial electroanatomic mapping very well.Conclusions: Nonsurgical transthoracic epicardial electroanatomicmapping is an feasible and safe methods. Infarcted tissue could be definedas bipolar electrogram amplitude＜0.5mV, normal tissue could be defined as＞1.5mV, bipolar electrogram amplitude between 0.5-1.5mV could be named asabnormal tissue. The reconstructed left ventricle of MRI can guide theendocardial and epicardial eleetroanatomic mapping of left ventricle.PartⅢNonsurgical Transthoracic EpicardialElectroanatomic Mapping and Radiofrequency Ablation ofVentricular Tachycardia after Healed MyocardialInfarctionObjective: To observe the feasibility and safety of the nonsurgicaltransthoracic epicardial electroanatomic mapping and radiofrequencyablation of ventricular tachycardia after healed myocardial infarction.Methods: Seven ZhongHua small pigs underwent the procedure toestablish chronic myocardial infarction model. The distal left anteriordescending of left coronary artery was occluded by percutaneousangioplasty balloon for 150 minutes. Ventricular tachycardia were inducedin electrophysiologic study after 3-5 weeks. Transthoracicpericardicentesis electroanatomic mapping and radiofrequency ablationwere performed in the survived pigs.Results: 8 kinds of ventricular tachycardia was induced beforeablation. Seven kinds of ventricular tachycardia showed right bundle branch block. One kind of ventricular tachycardia showed left bundlebranch block. The mean cycle length of ventricular tachycardia were338±66ms. Ventricular fibrillation was induced in one pigsimultaneously. The epicardial electroanatomic mapping was accomplishedsuccessfully under sinus rhythm in seven pigs. Ventricular tachycardiaweren't induced after ablation of the area between the scar tissue andmitral valve or normal tissue zone.Conclusions: Nonsurgical transthoracic epicardial electroanatomicmapping and radiofrequency ablation is an effective method to eliminateventricular tachycardia after healed myocardial infarction.