Three-dimensional endocardial impedance mapping: a new approach for myocardial infarction assessment

Precise identification of infarcted myocardial tissue is of importance in d iagnostic and interventional cardiology. A three-dimensional, catheter-base d endocardial electromechanical mapping technique was used to assess the ab ility of local endocardial impedance in delineating the exact location, siz e, and border of canine myocardial infarction. Electromechanical mapping of the left ventricle was performed in a control group (n = 10) and 4 wk afte r left anterior descending coronary artery ligation (n = 10). Impedance, bi polar electrogram amplitude, and endocardial local shortening (LS) were qua ntified. The infarcted area was compared with the corresponding regions in controls, revealing a significant reduction in impedance values [infarcted vs. controls: 168.8 +/- 11.7 and 240.7 +/- 22.3 Omega, respectively (means +/- SE), P< 0.05] bipolar electrogram amplitude (1.8 +/- 0.2 mV, 4.4 +/- 0. 7 mV, P< 0.05), and LS (-2.36 +/- 1.6%, 11.9 +/- 0.9%, P< 0.05). The accura cy of the impedance maps in delineating the location and extent of the infa rcted region was demonstrated by the high correlation with the infarct area (Pearson's correlation coefficient = 0.942) and the accurate identificatio n of the infarct borders in pathology. By accurately defining myocardial in farction and its borders, endocardial impedance mapping may become a clinic ally useful tool in differentiating healthy from necrotic myocardial tissue .