Three-Dimensional Ultrasound in Fetal Atrial, Ventricular and Atrioventricular Septal Defects
4D Fetal Echocardiography
Atrial, ventricular and atrioventricular septal defects are the most common cardiac anomalies in the humans and occur isolated or as part of other malformations in more than the half of children with a congenital cardiac anomaly. Whereas atrial defects are difficult to detect antenatally, ventricular and atrioventricular defects are detectable on two-dimensional and color Doppler ultrasound. Three-dimensional ultrasound as STIC technology allows in fetal septal defects on one hand a safe
... hand a safe description and documentation of the finding and on the other hand a spatial demonstration of the defect with the possibility of getting new views into the heart. The choice of the ideal plane from a 3D volume enables to get the in-line visualization of the interventricular septum with the septal defect. Orthogonal views help to visualize the defect in the different planes. Tomographic imaging aids in getting the upper abdomen and the great vessels information in addition to the septal defect view, in order to rule out a complex malformation. Rendering mode with the enface view can be used to visualize the septum from a lateral view and the common atrioventricular valve in atrioventricular septal defects. The combination with color Doppler helps to get the spatial demonstration of the defect within the heart and provide in addition information on flow events during the cardiac cycle in septal defects. DEFINITION Septal Defects: A septal defect is an opening of the septum causing communication between the two corresponding chambers, an atrial septal defect (ASD) being a communication between both atria and a ventricular septal defect (VSD) between both ventricles. An atrioventricular septal defect combines a ventricular septal defect with an atrial septum primum defect . Atrial Septal Defects (ASD): According to its location an ASD is classified into septum primum, septum secundum, sinus venosus and coronary sinus defect, but the most common is in 80% the septum secundum defect also called ASD II. Ventricular Septal Defects (VSD): Similarly ventricular septal defects (VSD) are classified according to their location and there are 4 types of VSD: perimembranous, muscular, inlet and outlet. Ventricular septal defects can be isolated or associated with other cardiac defects. Ventricular septal defects associated with conotruncal defects are outlet in location Atrioventricular Septal Defects (AVSD): AVSD are classified into partial AVSD which is a synonym of septum primum ASD and into a complete AVSD. In partial AVSD, two distinct mitral and tricuspid valve annuli exist whereas in complete AVSD there is typically an abnormal common atrioventricular valve which connects to the right and left ventricle. The common atrioventricular valve usually has 5 leaflets. Complete AVSD can in addition be classified as balanced or unbalanced. In unbalanced AVSD the atrioventricular connection predominantly drains to one of the two ventricles resulting in ventricular size disproportion. FETAL SEPTAL DEFECTS ON 2D-AND COLOR DOPPLER ULTRASOUND Atrial Septal Defect: It is practically impossible to diagnose reliably an isolated atrial septal defect in the fetus. ASD II is located in the foramen ovale region and it is not possible to predict whether a large foramen ovale will close postnatally or not.