Assessment of Atrial Septal Defect-Role of Real-Time 3D Color Doppler Echocardiography for Interventional Catheterization

Background: Atrial septal defect (ASD) is easily thought to be a round hole in the atrial septum from the image of two-dimensional (2D) echocardiography. Even surgeons can not get the true morphology of an atrial septal defect because they only see the defect when the heart is already in a collapsed, non-beating condition. Pediatric interventional cardiologists, on the contrary, need to know the exact morphology in the beating heart so that a therapeutic device can be safely deployed. The purpose of this study was to evaluate the accuracy of real-time three-dimensional echocardiography (RT-3D Echo) in visualizing the morphological characteristics of ASD and its potential as a new method for selecting the size of the Amplatzer septal occluder. Materials and Methods: Between February 2003 and December 2003, a total of 12 patients with secundum-type ASD underwent simultaneously 2D transesophageal echocardiography (TEE) and RT-3D Echo during interventional catheterization. The stretched balloon diameter, 2D TEE images, and RT-3D Echo images were recorded and analyzed in detail. Results: Twelve patients, aged from 3.0 to 36.0 years (mean 11.6±8.2 years), safely underwent the interventional catheterization. The mean Qp/Qs was 2.4±1.9 (range 1.6-4.5). The mean size (waist) of the 12 devices was 23.1±9.2 mm (range 7-36 mm). The mean SBD was 19.9±7.6 mm (range 6.0-34.1 mm). The mean 2D-TEE ASD measurement was 19.2±7.1 mm (range 5.4-33.5 mm). The mean RT-3D ASD measurement was 21.2±9.0 mm (range 6.1-34.5 mm). Analyses of the RT-3D Echo imaging showed that the ASD is not a flat hole in the septum. The ASD curves in three dimensions. The curvature varied differently in different directions, thus generating a complex spatial structure. The calculated curvature angles along long axis of defects were 166±5.4 degrees. Good correlations were found between device diameter (waist) and SBD (r=0.995), 2D diameter (r=0.987), and 3D diameter (r=0.997). The best correlation was found between device diameter (waist) and 3D diameter measured by planimetry of RT-3D Echo (r=0.997). Conclusions: The complex 3D nature of the ASD in the beating heart could only be well appreciated by the RT Color 3D Echo. The conventional 2D image provided only partial and thus distorted image of ASD. Thus, the application ofRT-3D Echo provides a useful tool for evaluation of ASD for those patients undergoing interventional transcatheter closure.