[Estimation of location and size of myocardial infarction from body surface potentials using the ECG inverse solution method].

This paper describes a non-invasive mathematical method for estimating the locations and sizes of myocardial infarction using body surface electrocardiographic mappings. The inverse calculation is the theoretical basis of our method of estimation. First, the boundary integral equations were used to relate body surface and epicardial potential distributions. Next, a spherical harmonic expansion was used to solve the equations in order to obtain the epicardial potentials from the body surface potentials. The validity of the method was assessed by animal experiments and the clinical application. Body surface potentials were recorded using a 128 channel electrocardiographic mapping device equipped with a 16 bit microprocessor. In the animal study, the epicardial potentials were recorded by another potential mapping device simultaneously with body surface potential recordings. In the animal study, 60 epicardial electrodes and a freezing unit were mounted on a elastic fabric sack and attached to the heart. After completion of open chest surgery, freezing myocardial injury was incurred by perfusing -50 degrees C acetone-dry ice cryogen into the freezing unit. Twenty minutes after the start of freezing, ST elevations of the body surface and epicardial potentials were simultaneously recorded. An ST subtraction map was compiled as the difference between the maps before and after the myocardial freezing injury. Then, an inverse calculation was applied to the ST subtraction potentials to estimate the epicardial ST elevation. The geometric parameters of each electrode were determined from stereometry using two-dimensional X-ray images. In the clinical study, the body surface potentials of a patient with old myocardial infarction were recorded. The abnormal Q subtraction map was calculated as the difference between the measured and standard potentials of a normal subject. In the inverse calculation, the geometric shape of the heart and the body surface were determined from cross-sectional body images of computed tomography. The location of the infarction was estimated independently using coronary arteriography and left ventriculography. The results obtained were as follows: Experimentally, the estimated epicardial ST elevations correlated well with the measured ones. The area of estimated ST elevation included the portion of the myocardial injury produced by the freezing procedure, although the area estimated was relatively small compared with the actual one. Clinically, the estimated abnormal Q area correlated well with the area of the left anterior descending artery in which severe stenosis was detected by coronary arteriography.(ABSTRACT TRUNCATED AT 400 WORDS)