LESIONS THAT CAUSE AORTIC FLOW DISTURBANCE

Echo Doppler examination purports to localize the origin of flow disturbances within the heart or great vessels. During our investigation of echo Doppler, frequency dispersions found in the transverse aortic arch, ascending aorta or right pulmonary artery that should indicate flow disturbances in those areas occurred in a set of lesions that did not involve the expected cardiac anatomic abnormalities. To learn the range of this false-positive problem, we reviewed all of our documented cases in which an echo Doppler had been obtained (n=127). Our results indicate that 48% of our patients who had right pulmonary artery disturbances had additional flow disturbances detected in the ascending aorta or transverse aortic arch despite the fact that cardiac catheterization in these patients indicated absence of an anatomic abnormality in the left side of the heart. These false positives had the highest incidence of occurrence in patients who had high left cardiac output, but this also occurred in four instances in which the only cardiac lesion was pulmonary stenosis. The latter is thought to be due to an induced flow disturbance. We also found two patients whose only lesion was aortic stenosis, but these patients had secondary flow disturbances in the pulmonaroy artery; these two instances probably represent a flow disturbance induced from the aorta to the pulmonary artery. Knowledge of this set of false-positive results is important for proper interpretation of echo Doppler examinations.