Echocardiographic findings in experimental myocardial infarction of the posterior left ventricular wall

Abstract

The effects of experimental infarction of the posterior left ventricular wall on the echocardiographic configuration and motion of the posterior left ventricular endocardium were evaluated in 20 closed chest dogs. Myocardial infarction was produced by selected intubation of the circumflex coronary artery and injection of blood clots. The electrocardiogram, phonocardiogram, apexcardiogram, aortic and left ventricular pressure curves, and left ventricular dP dt were recorded simultaneously and superimposed on the echocardiographic tracing. Correlation of the echocardiogram with the other measurements permitted the calculation of left ventricular volumes, contractility and systolic and diastolic time intervals. Specific echocardiographic changes in the configuration of the posterior left ventricular endocardium occurred synchronously with left ventricular mechanical performance regardless of S-T segment changes in the electrocardiogram. Reduction of excursion and mean and maximal velocity of excursion of the posterior left ventricular endocardium were indicative of experimental posterior wall infarction. Changes in the echocardiographic configuration of the posterior left ventricular endocardium could be correlated with upright and inverted T waves. Experimental infarction of the posterior left ventricular wall was always reflected in changes in the posterior left ventricular endocardial echo, whethe the infarction was transmural or nontransmural. In contrast, the electrocardiogram failed to show changes in nontransmural infarction. The study may form the basis for an interpretation of echocardiographic findings in posterior wall infarction in man.