Epicardial ST depression in acute myocardial infarction.

The presence of electrocardiographic ST depression in acute infarction remains controversial and poorly explained. A combined animal and modeling study was performed to evaluate the source of ST changes in acute infarction. In anaesthetized sheep, small infarcts showed uniform ST elevation over the infarction whereas larger infarcts showed marked ST depression over the normal myocardium in addition to the ST elevation. These findings were replicated by bidomain models of the heart. A hollow sphere was used to model a gradually increasing infarct, and this showed that there was a decrease in the ratio of ST elevation to ST depression as the infarct was increased. The current flowing out of the heart must be identical to the current flowing back into the heart. This means that any infarction will produce ST depression as well as ST elevation, the ratio between the two being related to the size of the infarction. Small infarction is associated with a small region of ST elevation and minor ST depression of the remaining myocardium, and as the infarct region increases, the amplitude of the epicardial ST elevation falls and the amplitude of the ST depression increases. Infarction size is proportional to both the height of the ST depression on the epicardium and the strength of the epicardial ST segment dipole.

[1]  A. M. Scher,et al.  Mechanism of S‐T Segment Alteration During Acute Myocardial Injury , 1960, Circulation research.

[2]  Franklin D. Johnston,et al.  Electrocardiograms that represent the potential variations of a single electrode , 1934 .

[3]  A. Ekmekci,et al.  Angina pectoris: IV. Clinical and experimental difference between ischemia with S-T elevation and ischemia with S-T depression , 1961 .

[4]  G. Geary,et al.  Epicardial Mapping and Electrocardiographic Models of Myocardial Ischemic Injury , 1979, Circulation.

[5]  E. Schenk,et al.  A Solid Angle Analysis of the Epicardial Ischemic TQ‐ST Deflection in the Pig: A Theoretical and Experimental Study , 1978, Circulation research.

[6]  R. Califf,et al.  Precordial ST segment depression predicts a worse prognosis in inferior infarction despite reperfusion therapy. The Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) Study Group. , 1990, Journal of the American College of Cardiology.

[7]  D. Kelly,et al.  Mechanism and significance of precordial ST-segment depression during inferior wall acute myocardial infarction associated with severe narrowing of the dominant right coronary artery. , 1993, The American journal of cardiology.

[8]  D. Kilpatrick,et al.  VALIDATION OF A SUBENDOCARDIAL ISCHAEMIC SHEEP MODEL BY INTRACORONARY FLUORESCENT MICROSPHERES , 1996, Clinical and experimental pharmacology & physiology.

[9]  R. Kleiger,et al.  Long-term prognostic significance of ST segment depression during acute myocardial infraction☆ , 1993 .

[10]  R. Holland,et al.  Precordial and Epicardial Surface Potentials during Myocardial Ischemia in the Pig: A THEORETICAL AND EXPERIMENTAL ANALYSIS OF THE TQ AND ST SEGMENTS , 1975, Circulation research.

[11]  S J Walker,et al.  Derived epicardial potentials differentiate ischemic ST depression from ST depression secondary to ST elevation in acute inferior myocardial infarction in humans. , 1989, Journal of the American College of Cardiology.

[12]  G. MICHAEL VINCENT,et al.  Mechanisms of Ischemic ST-Segment Displacement: Evaluation by Direct Current Recordings , 1977, Circulation.

[13]  R. Gibbons,et al.  Significance of anterior ST depression in inferior wall acute myocardial infarction. , 1994, The American journal of cardiology.

[14]  D. Mirvis,et al.  Physiologic bases for anterior ST segment depression in patients with acute inferior wall myocardial infarction. , 1988, American heart journal.

[15]  D Kilpatrick,et al.  Source of electrocardiographic ST changes in subendocardial ischemia. , 1998, Circulation research.

[16]  D. Ferguson,et al.  Angiographic evidence that reciprocal ST-segment depression during acute myocardial infarction does not indicate remote ischemia: analysis of 23 patients. , 1984, The American journal of cardiology.

[17]  R M Gulrajani,et al.  A computer heart model incorporating anisotropic propagation. IV. Simulation of regional myocardial ischemia. , 1996, Journal of electrocardiology.

[18]  D Durrer,et al.  Mechanism and Time Course of S‐T and T‐Q Segment Changes during Acute Regional Myocardial Ischemia in the Pig Heart Determined by Extracellular and Intracellular Recordings , 1978, Circulation research.

[19]  M. H. Forman.  Precordial ST-segment depression during acute inferior myocardial infarction: Clinical, scintigraphic and angiographic correlations , 1984 .

[20]  W. Shen,et al.  Anterolateral ST segment depression in acute inferior myocardial infarction: angiographic and clinical implications. , 1984, American heart journal.