MULTIRESOLUTION WAVELET ANALYSIS OF THE BODY-SURFACE ECG BEFORE AND AFTER ANGIOPLASTY

Electrocardiographic recordings of patients with coronary artery steno sis, made before and after angioplasty, were analyzed by the multireso lution wavelet transform (MRWT) technique. The MRWT decomposes the sig nal of interest into its coarse and detail components at successively finer scales. MRWT was carried out on different leads in order to comp are the P-QRS-T complex from recordings made before with those made af ter percutaneous transluminal coronary angioplasty (PTCA). ECG signals before and after successful PTCA procedures show distinctive changes at certain scales, thus helping to identify whether the procedure has been successful. In six patients who underwent right coronary artery P TCA, varying levels of reperfusion were achieved, and the changes in t he detail components of ECG were shown to correlate with the successfu l reperfusion. The detail components at scales 5 and 6, corresponding approximately to the frequencies in the range of 2.3-8.3 Hz, are shown to be the most sensitive to ischemia-reperfusion changes (p < 0.05). The same conclusion was reached by synthesizing the post-PTCA signals from pre-PTCA signals with the help of these detail components. For on -line monitoring a vector plot, analogous to vector cardiogram, of the two most sensitive MRWT detail components is proposed. Thus, multires olution analysis of ECG may be useful as a monitoring and diagnostic t ool during angioplasty procedures.