Negative contrast echocardiography: a new method for detecting left-to-right shunts.

Abstract

Cross-sectional echocardiographic visualization of the interatrial septum in both normal persons and patients with atrial septal defects was reported. Although septal defects can generally be visualized, false positives are frequently encountered. Whether visualizing the patterns of contrast flow in the region of an apparent atrial septal defect by cross-sectional echocardiography could aid in the differentiation of true defects from false positives was evaluated. Patients (25) (13 with intact interatrial septa and 12 with atrial septal defects) were studied. Contrast was visualized in the right atrium in 24 of 25 patients (all 13 normal patients and 11 of 12 patients with atrial septal defects). In all patients with intact interatrial septum, the peripherally injected contrast material homogenously filled the right atrium, delineating the position and integrity of the interatrial septum. In 2 of 11 patients with atrial septal defects, evidence of right-to-left shunting through the defect confirmed its presence. In the remaining 9 patients, the flow of blood from left atrium to right atrium, following the path of the left-to-right shunt, produced an echo-free area along the right margin of the interatrial septum, or an area of negative contrast. This phenomenon was produced by the non-contrast-containing blood flowing through the septum and displacing the contrast-containing blood from along the right-hand portion of the septum. Peripheral injection of echocardiographic contrast material possibly may be of value in detecting atrial septal defects in patients with predominant left-to-right shunting when contrast flows are evaluated using cross-sectional echocardiography.