Jacobson Jason T, Afonso Valtino X, Eisenman Gregory, Schultz John R, Lazar Sorin, Michele John J, Josephson Mark E, Callans David J
Division of Cardiovascular Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Heart Rhythm. 2006 Feb;3(2):189-97. doi: 10.1016/j.hrthm.2005.11.007.
Conventional mapping of ventricular tachycardia (VT) after myocardial infarction is limited in patients with hemodynamically untolerated or noninducible VT.
The purpose of this study was to develop a unique strategy using noncontact unipolar mapping to define infarct substrate and VT circuits.
Dynamic substrate mapping (DSM) was performed in seven pigs with healed anterior myocardial infarction. This technique defined substrate as the intersection of low-voltage areas identified in sinus rhythm and during pacing around the infarct. Pacing was also performed within the substrate to determine exit sites.
Anteroapical transmural scar was identified in all animals. A mean of three pacing sites was used for substrate definition. The mean area (+/- SD) was 18.4 +/- 8.8 cm2 by DSM and 15.4 +/- 6.9 cm2 by pathology (P >.5). A mean of 4.5 sites was paced within substrate. Ten of 18 paced wavefronts exited substrate adjacent to the pacing area, seven exited at distant areas, and one had two exits. VT was induced in five animals (1.6 morphologies per animal). Except for one VT, circuit exit sites were identified at substrate borders on the endocardium. VT exit sites were at (n = 6) or near (n = 3) a pacing exit site. Electrogram voltages differed significantly between substrate, border, and nonsubstrate areas in infarcted animals and in comparison with control animals. No substrate was identified in two control animals.
DSM is a reliable method for infarct substrate localization in this model. Pacing within substrate can predict VT exit sites and may prove useful for ablation of unmappable VT after myocardial infarction.
在血流动力学不耐受或不能诱发的室性心动过速（VT）患者中，心肌梗死后传统的VT标测受到限制。
本研究的目的是开发一种独特的策略，使用非接触单极标测来定义梗死基质和VT环路。
对7只患有陈旧性前壁心肌梗死的猪进行动态基质标测（DSM）。该技术将基质定义为在窦性心律和围绕梗死灶起搏时识别出的低电压区域的交集。还在基质内进行起搏以确定出口部位。
所有动物均发现前尖部透壁瘢痕。平均使用3个起搏部位来定义基质。DSM测得的平均面积（±标准差）为18.4±8.8 cm²，病理测得的平均面积为15.4±6.9 cm²（P>.5）。在基质内平均起搏4.5个部位。18个起搏波前中有10个在靠近起搏区域的基质边界处离开基质，7个在远处区域离开，1个有两个出口。5只动物诱发了VT（每只动物1.6种形态）。除1例VT外，在心肌内膜的基质边界处识别出环路出口部位。VT出口部位位于（n = 6）或靠近（n = 3）起搏出口部位。梗死动物的基质、边界和非基质区域之间以及与对照动物相比，心电图电压有显著差异。2只对照动物未发现基质。
在该模型中，DSM是梗死基质定位的可靠方法。在基质内起搏可预测VT出口部位，可能对心肌梗死后无法标测的VT消融有用。
