NDLI: Ischemia-related depolarization changes detected in body-surface ambulatory ECG recordings

Content Provider	IEEE Xplore Digital Library
Author	Gramatikov, B. Iyer, V.
Copyright Year	2000
Description	Author affiliation: Dept. of Biomed. Eng., Johns Hopkins Univ., Baltimore, MD, USA (Gramatikov, B.)
Abstract	It is well known that myocardial ischemia causes changes in the the ST-segment of the ECG. Unfortunately, not all ischemic states are reflected by the ST-level. Recent studies show that myocardial ischemia alters not only the repolarization phase, but it also affects the depolarization phase of the heart, subsequently altering electrical conduction patterns, and giving rise to ischemia-dependent changes in the QRS complex. These changes could be utilized in formulating clinical diagnosis. From the European ST-T data base the authors analyzed all 8 patients with single-vessel LAD occlusion, for which a modified lead III and V/sub 3/ or V/sub 4/ were available. The authors calculated the time-frequency distributions during the averaged QRS complex, using the continuous wavelet transform. From these distributions, an intra-QRS subband energy index was calculated by integrating the coefficients across the QRS complex, for four overlapping subbands: LF (24-35 Hz), MF (30-45 Hz), HF (40-60 Hz), and HHF (50-80 Hz). Finally, each subband index was normalized (% of total QRS energy), trended across the 120-min recording, then low-pass filtered with a cosine window of length 2 min 20 sec, and plotted. In all 8 patients ST and T changes were accompanied by intra-QRS changes in all subbands during the ST episode. The authors observed a relative drop in the energy in subband LF, while the MF index went up. HF first dropped, during the first half of the ST episode, then increased towards the end of the episode. HHF typically decreased-due to loss of fine structure in the depolarization wavefront.
Starting Page	912
Ending Page	914
File Size	286000
Page Count	3
File Format	PDF
ISBN	0780364651
ISSN	1094687X
DOI	10.1109/IEMBS.2000.897868
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2000-07-23
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Myocardium Ischemic pain Continuous wavelet transforms Hafnium Electrocardiography Heart Clinical diagnosis Time frequency analysis Wavelet transforms Low pass filters
Content Type	Text
Resource Type	Article

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