Assessment of myocardial ischemia through high frequency energy estimation over the time-frequency plane using wavelets

This study describes total energy changes over eight regions of the QRS time-frequency (TF) plane, during percutaneous transluminal coronary angioplasty (PTCA). The study population consisted of 43 patients undergoing PTCA, with no previous myocardial infarction history: 25 in the right coronary (RCA), 10 in left anterior descending (LAD) and 8 in left circumflex (LCX) arteries. Blockwise and exponential signal averaging technics were used at pre-processing stage; continuous Morlet wavelet transform and total energy calculation were applied. Significant changes were found in the HF regions (p<0.05) in patients assessed at the end of the PTCA (80-250 Hz/second QRS half) compared with their values previous to inflation. Total energy over specific time-frequency regions, assessing high frequency using a frequency band from 80 to 250 Hz, could be used as a marker for ischemic events during depolarization. These results suggest that leads II and aVF are more sensitive to such changes.