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.