Dynamical behavior of intra-QRS potentials during induced myocardial ischemia

Assesses the prevalence and natural progression of abnormal intra-QRS potentials (AIQPs) in high-resolution electrocardiography (HRECG) during percutaneous transluminal coronary angioplasty (PTCA). 25 patients were studied: seven had occlusion of the left anterior descending (LAD) artery, nine of the left circumflex (LCX) and nine of the right coronary artery (RCA). HRECGs with enhanced signal-to-noise ratio were obtained every 60 seconds from a sub-ensemble of beats using a time-frequency-plane Wiener filter. AIQP QRS high-frequency components and ST segment deviation were estimated every 60 seconds. Mean values of AIQP amplitudes increased rapidly during the first minute of balloon inflation compared to the pre-inflation recording. The increase is maintained throughout the inflation period, decreasing after the inflation period. An analysis of variance (ANOVA) showed very significant changes in AIQP values between pre-inflation and inflation epochs (p<0.001). A relationship between AIQP timing, measured as the ´center of mass´ of the AIQP signal, and the location within the artery (LAD, LCX and RCA) was found during the first minute of inflation (p=0.02); AIQP timing occurs later in RCA occlusion. These observations suggest that AIQP shows promise as a time-localized sensitive marker of ischemically altered ventricular activation