ANALYSIS OF PTCA-INDUCED ISCHEMIA USING AN ECG INVERSE SOLUTION OR THE WAVELET TRANSFORM

In patients without significant collaterals, percutaneous transluminal coronary angioplasty (PTCA) produces acute transient ischemia that is delectable in both standard electrocardiograms (EGG) and body surface potential maps (BSPMs). Control recordings made before or between inf lations provide personalized baselines, which isolate the effects of i schemia from interpatient differences, such as torso shape and electro de location. In this study, two methods of evaluating PTCA-induced isc hemia from BSPM recordings are presented. In the first method, an ECG inverse solution that estimates epicardial potentials from body surfac e signals using a realistic model of torso geometry is applied. The st rength of this method lies in its potential ability to localize areas of cardiac ischemia on the epicardial surface. In the second approach, wavelet transforms were used to perform a multiresolution decompositi on of the BSPM data into different frequency bands. The basis function s of the wavelet transform are time-limited and narrow band and hence can be expected to be sensitive to features of the BSPM that originate in discrete electrophysiologic events, such as intrusion of the activ ation front onto regions of ischemia or arrhythmias due to local condu ction abnormalities. The method also offers a means of temporal and fr equency localization of cardiac events related to the initiation of in jury currents and abnormal conduction due to PTCA-induced ischemia. Th e inverse solution and the wavelet transform each offer new views of t he spatial and temporal courses of acute ischemia potentially leading to new diagnostic insights in ECG patient examination.