The interatrial septal echocardiogram: relationship to left atrial volume change in the normal and diseased heart

The echocardiogram of the interatrial septum (IAS) was examined using the right-sided parasternal approach. The IAS can be detected in 56% of patients with heart disease and in 24% of normal subjects. In this study, we analyzed 15 normal subjects and 35 patients with right (RA) or left (LA) atrial overloading. The normal IAS shows anterior motion during ventricular systole and predominantly posterior motion in three phases during ventricular diastole. The normal IAS motion is easily correlated with events in the cardiac cycle and reflects LA volume change. In patients with pure mitral stenosis (MS), the IAS was motionless and the total amplitude of the IAS echocardiogram was decreased. In seven patients with pure mitral regurgitation (MR), the features of systolic fluttering (SF) and systolic premature anterior motion (SPAM) of the IAS movement were noted in three and six patients, respectively. The total amplitude of the IAS echocardiogram was increased. In 14 patients with MS combined with MR, SPAM was noted in six patients and three other patients presented SF of the IAS. The total amplitude of the IAS echocardiogram was normal or decreased. In two patients with tricuspid regurgitation, a reverse systolic motion of the IAS was found. These abnormal IAS motions can be explained on the basis of LA volume changes in each type of heart disease. Thus, a study of IAS motion can aid the understanding of various cardiac disease states.