Reddy Vivek Y, Wrobleski David, Houghtaling Christopher, Josephson Mark E, Ruskin Jeremy N
Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Circulation. 2003 Jul 1;107(25):3236-42. doi: 10.1161/01.CIR.0000074280.62478.E1. Epub 2003 Jun 9.
Substrate mapping of post-myocardial infarction ventricular tachycardia involves electroanatomic delineation of scarred tissue on the basis of electrogram characteristics during sinus rhythm. A percutaneous transthoracic technique was recently described that allows catheter mapping of the epicardial surface of the heart. This study sought to determine whether the epicardial extent of a myocardial infarct could be defined during sinus rhythm.
In a porcine model of healed anterior wall myocardial infarction (n=13 animals), detailed in vivo left ventricular endocardial and ventricular epicardial electroanatomic mapping was performed. Catheter access to the pericardial space was achieved by subxyphoid puncture under fluoroscopic guidance. Bipolar electrogram amplitude and duration characteristics of normal tissue were established on the basis of in vivo epicardial mapping data in 8 additional normal animals. With the use of these criteria, radiofrequency lesions (4 to 11 per animal) were placed along the endocardial and epicardial scar borders as defined by the electroanatomic map. The area of epicardial scar defined by abnormal bipolar voltage correlated well with the dimensions measured on pathological examination. The size and location also correlated well with the scar dimensions defined by electrogram duration criteria. Late potentials were noted in the border zones of both surfaces of the scar. During pathological examination, the radiofrequency lesions were situated at the borders of the epicardial scar.
A 3-dimensional construct of the infarcted myocardium can be rendered by combined epicardial and endocardial electroanatomic mapping. This experimental protocol is propaedeutic to future clinical studies incorporating endocardial and epicardial substrate mapping into catheter ablation strategies to treat post-myocardial infarction ventricular tachycardia.
心肌梗死后室性心动过速的基质标测涉及根据窦性心律期间的心电图表征对瘢痕组织进行电解剖描绘。最近描述了一种经皮经胸技术，可实现心脏心外膜表面的导管标测。本研究旨在确定心肌梗死的心外膜范围是否可在窦性心律期间确定。
在愈合的前壁心肌梗死猪模型（n = 13只动物）中，进行了详细的体内左心室心内膜和心外膜电解剖标测。在荧光镜引导下通过剑突下穿刺实现进入心包腔的导管通路。根据另外8只正常动物的体内心外膜标测数据确定正常组织的双极心电图幅度和持续时间特征。使用这些标准，沿着电解剖图定义的心内膜和心外膜瘢痕边界放置射频损伤（每只动物4至11个）。由异常双极电压定义的心外膜瘢痕面积与病理检查测量的尺寸密切相关。大小和位置也与由心电图持续时间标准定义的瘢痕尺寸密切相关。在瘢痕两面的边界区域均记录到晚期电位。在病理检查期间，射频损伤位于心外膜瘢痕的边界处。
通过心外膜和心内膜电解剖标测相结合可构建梗死心肌的三维结构。该实验方案是未来临床研究的前奏，这些研究将心内膜和心外膜基质标测纳入导管消融策略以治疗心肌梗死后室性心动过速。
