Regional myocardial function and dimensions early and late after myocardial infarction in the unanesthetized dog.

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Abstract
Pairs of ultrasonic dimension gauges and a micromanometer implanted in the subendocardium of the left ventricles of unanesthetized dogs were used to analyze serial changes in hemodynamic status and segmental function for up to 4 weeks after permanent circumflex coronary artery occlusion. Regional function was studied in control segments and in segments identified as marginal (hypokinetic) and ischemic. In three dogs, after transient regional dysfunction, no myocardial infarction developed, whereas in five dogs regional dysfunction at 3 hours after occlusion was followed by the development of persistent dysfunction and infarction. Left ventricular end-diastolic segment length (EDL) changes over time; EDL of the control segments increased progressively, but in marginal segments EDL was 12% below control and in the ischemic segments 30% below control by 4 weeks. Progressive increases in percent active shortening occurred in control segments; but holosystolic bulging was replaced by akinesia in ischemic segme...