Non-destructive, High-resolution 3-dimensional Visualization of a Cardiac Defect in the Chick Embryo Resembling Complex Heart Defect in Humans Using Micro-computed Tomography: Double Outlet Right Ventricle With Left Juxtaposition of Atrial Appendages

Nondestructive, high-resolution 3-dimensional (3D) imaging of the embryonic heart remains a challenge in cardiovascular development research. In the past, several imaging techniques (eg, magnetic resonance microscopy, optical coherence tomography) were tested for their suitability to visualize the 3D morphology of embryonic hearts. Most of these imaging tools have their drawbacks with respect to resolution and depth penetration. Here we present, to the best of our knowledge, the first high-resolution 3D images of normal and malformed embryonic chick hearts at the 10 μm level generated by microcomputed tomography (micro-CT) examination of critical point-dried heart specimens. Cardiac anatomy is demonstrated in great details with respect to myocardial fiber arrangement and trabeculations as well as atrioventricular (AV) and semilunar valves. Positions of great vessels with associated ventricular septal defects are visualized in high quality in malformed hearts. Figure 1A shows the normal 4-chambered heart of a day 9 chick embryo with correct positioning of the heart chambers and great vessels. Figure 1B depicts an image of a malformed embryonic chick heart in which both great arteries are significantly shifted toward the right side with extreme dextroposition of the aorta, and both great arteries arise from the right ventricle (double outlet right ventricle [DORV]). Note also that both atrial appendages are located to the left of the great arteries (left juxtaposition of atrial appendages [LJAA]). The cardiac defect that we present here in the chick embryo resembles a rare complex heart defect known in humans, as depicted in a classic drawing by Frank Netter, MD, in the Netter Collection of Medical Illustrations – Heart (Figure 1C, reproduced with permission from netterimages.com). Figure 1. Photographs of day 9 embryonic chick hearts (A and B, respectively) and a drawing of a malformed human …