[Electrocardiogram simulation. A theoretical model of ischemia].
Using an electric circuit model, made of two segments formed of sections that behave electrically as subendocardial and subepicardial cells, we simulated myocardial ischemia in one of the two segments. The changes in the ST segment and in the T wave were obtained respectively by diminishing the intercellular potential from -90 mV to -60 mV and by shortening or prolonging the duration of action potentials. In order to simulate acute subendocardial, subepicardial and transmural ischemia, the potentials of the internal section, the outer section, and of both sections were diminished respectively. The ST segment appeared depressed both in the segment involved and in the undamaged one in subendocardial ischemia. In subepicardial ischemia it appeared elevated in the segment involved and was normal in the undamaged one. In transmural ischemia it was elevated in the segment with reduced potential and it was depressed in the undamaged segment. The depression of the ST segment in the undamaged part, both in subendocardial ischemia and in transmural ischemia, depends on the imbalance of the central point and therefore the whole subendocardial layer behaves electrically as if it really were ischemic. The T-wave changes in acute ischemia are in keeping with those of the ST segment.
Clinica Medica II, Università degli Studi di Firenze.
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Morace
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Alcidi
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Fantini
D000200:Action Potentials; D003327:Coronary Disease / Q000503:physiopathology*; D004562:Electrocardiography; D006801:Humans; D008955:Models, Cardiovascular
La simulazione dell'elettrocardiogramma. Un modello teoretico di ischemia.