The Posterior Aortic Wall Echocardiogram Its Relationship to Left Atrial Volume Change

SUMMARY The normal posterior aortic wall echocardiogram shows anterior motion during left ventricular systole and predominantly posterior motion in three phases during left ventricular diastole. In six patients undergoing simultaneous left atrial angio-grams and posterior aortic wall echocardiograms, there was excellent correlation between the posterior aortic wall motion and the change in the left atrial angiographic area showing the value of the posterior aortic wall echocardiogram in describing the left atrial volume curve. IN 1969 Hirata et al. demonstrated that the left atrial dimension on the echocardiogram correlated well with the maximum left atrial angiographic dimension. ' Since then others have confirmed these findings and the maximum left atrial echo dimension has become a routine part of the echo-cardiographic report.2 3 In fact the aorta and left atrium may be the only recordable echocardiographic structures in some difficult patients such as those with chronic lung dis-ease. The left atrial dimension is normally measured at the point of maximum separation of the posterior aortic wall from the posterior left atrial wall corresponding to the max-imum distension of the left atrium with pulmonary venous blood. The similarity between the cyclic change in this measurement and the left heart volume curve has intrigued us. However, the diagnostic value of the cyclic change in left atrial echocardiographic dimension and factors affecting it are unclear from previous work.4 ' Since most of the change in the left atrial echocardiographic dimension is due to pos-terior aortic wall motion, this study was designed to explore the factors influencing the posterior aortic wall motion and to assess the importance of the cyclic change in left atrial volume on this motion