Objective
Three-dimensional echocardiography offers new insights into the morphology of atrioventricular septal defects (AVSD). In this setting, the alignment of the atrial and ventricular septums is disrupted leading to variation in the venous return in to corresponding ventricles. We attempted to establish the orientation of the atrial and ventricular septums relative to each other and the atrioventricular junction to study its impact on septatability.
Methods
We evaluated 31 patients using 3-dimensional echocardiography. Off-line analysis using Tometec was used for multiplanar review. In 4 chamber view crux of the heart was identified to define the relation of the muscular ventricular septum to the crux. We drew a line along long axis of the ventricular septum to join the leading edge of the atrial septum thus defining the plane of AVSD. A second line was constructed along long axis of the atrial septum. The angle formed between these two lines was measured.
Results
Biventricular repair proved possible in 21 patients. The atrial septum was parallel to ventricular septum in 14 while 7 had angulation (mean angle 11.8). Patients with unbalanced ventricles had significant angulation (n=10 mean 29 p=<0.0002) One patient had 1-1/2 ventricular repair while another had biventricular repair incorporating a prosthetic left atrioventricular valve. Three died and five had successful single ventricle palliation. Atrial septal angles more than 26 predicted adverse outcome.
Conclusions
Multiplanar review of three-dimensional data sets is valuable for assessing the septatability of AVSD. Malalignment of septal structures may be a substrate for underdevelopment of the ventricular volume.