title: High-intensity focused ultrasound ablation of myocardium in vivo and instantaneous biological response.
abstract: OBJECTIVE
  This study aimed to evaluate the instantaneous biological response of canine myocardium in vivo to high-intensity focused ultrasound (HIFU) ablation, and thereby determine the feasibility of this method.
  
  
  METHODS
  Left ventricle myocardium HIFU ablation was performed on six dogs at four levels of HIFU energy (acoustic intensity was 3000 W/cm2 ; ablation durations were 1.2, 2.4, 3.6, and 4.8 sec, respectively). Gross lesion volumes were confirmed and assessed by tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and electron microscopy. Global cardiac function and focal wall motion were evaluated by echocardiography. Blood enzymes and cardiac troponin T (CTnT) were tested after ablation. HIFU ablation was repeated on another set of six fresh canine hearts in vitro at the same four energy levels. Focal maximum temperatures were detected both in vivo and in vitro.
  
  
  RESULTS
  Different sizes of ablation via HIFU can be created in beating hearts using controlled energy emission. Focal maximum temperatures varied from 62 ± 4.8 °C to 81 ± 12.9 °C. The lesion sizes were significantly smaller in vivo than in vitro, as verified by TTC and HE staining. Focal wall motion immediately decreased after ablation (P < 0.05), although the ejection fraction (EF) and E/A ratio were unchanged (P > 0.05). Enzymes and CTnT immediately increased.
  
  
  CONCLUSIONS
  HIFU can be used for the controllable ablation of myocardial tissue, with instantly increased serum markers, decreased regional wall motion, and unaffected left ventricular global function.
authors: Ultrasound Department, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors: Minjuan
authors: M
authors: Zheng
authors: Weihui
authors: W
authors: Shentu
authors: Dingzhang
authors: D
authors: Chen
authors: David J
authors: DJ
authors: Sahn
authors: Xiaodong
authors: X
authors: Zhou
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D004285:Dogs; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D066298:In Vitro Techniques / Q000379:methods; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008854:Microscopy, Electron / Q000379:methods; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D020107:Troponin T / Q000097:blood; D014463:Ultrasonography
chemical_list: D020107:Troponin T; D007770:L-Lactate Dehydrogenase; D001219:Aspartate Aminotransferases; D003402:Creatine Kinase
keywords: cardiac ablation; echocardiography; high-intensity focused ultrasound