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Source of electrocardiographic ST changes in subendocardial ischemia


Li, DS and Li, CY and Yong, AC and Kilpatrick, D, Source of electrocardiographic ST changes in subendocardial ischemia, Circulation Research, 82, (9) pp. 957-970. ISSN 0009-7330 (1998) [Refereed Article]

DOI: doi:10.1161/01.RES.82.9.957


To clarify the source of electrocardiographic ST depression associated with ischemia, a sheep model of subendocardial ischemia was developed in which simultaneous epicardial and endocardial ST potentials were mapped, and a computer model using the bidomain technique was developed to explain the results. To produce ischemia in different territories of the myocardium in the same animal, the left anterior descending coronary artery and left circumflex coronary artery were partially constricted in sequence. Results from 36 sheep and the computer simulation are reported. The distributions of epicardial potentials from either ischemic source were very similar (r=0.77±0.14, P(0.0001), with both showing ST depression on the free wall of the left ventricle and no association between the ST depression and the ischemic region. However, endocardial potentials showed that ST elevation was directly associated with the region of reduced blood flow. Insulating the heart from the surrounding tissue with plastic increased the magnitude of epicardial ST potentials, which was consistent with an intramyocardial source. Increasing the percent stenosis of a coronary artery increased epicardial ST depression at the lateral boundary and resulted in ST elevation starting from the ischemic center as ischemia became transmural. Computer simulation using the bidomain model reproduced the epicardial ST patterns and suggested that the ST depression was generated at the lateral boundary between ischemic and normal territories. ST depression on the epicardium reflected the position of this lateral boundary. The boundaries of ischemic territories are shared, and only those appearing on the free wall contribute to external ST potential fields. These effects explain why body surface ST depression does not localize cardiac ischemia in humans.

Item Details

Item Type:Refereed Article
Research Division:Biomedical and Clinical Sciences
Research Group:Cardiovascular medicine and haematology
Research Field:Cardiology (incl. cardiovascular diseases)
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Li, CY (Ms Chuan Yong Li)
UTAS Author:Yong, AC (Dr Ah Chot Yong)
UTAS Author:Kilpatrick, D (Professor David Kilpatrick)
ID Code:13233
Year Published:1998
Web of Science® Times Cited:75
Deposited By:Medicine
Deposited On:1998-08-01
Last Modified:2011-08-08

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