(a) Specimen 1100. The frontal view of mitral atresia combined with pulmonary atresia shows the fine main pulmonary artery at the back of the aorta. (b) Specimen 1100. The blue bougie indicates the fine main pulmonary artery. The blind-end root confirms the pulmonary atresia. RA hypertrophic and dilated right atrium, RV right ventricle, the only ventricular chamber of this specimen. (c) Specimen 1100. Ventricular anterior wall opened to expose the right atrium and outflow tract of the right ventricle. The structure of the atrioventricular valve conforms to the characteristics of the TV. The multiple muscle trabeculae, conical muscle-like structures between the aortic and tricuspid valves, could confirm that the chamber is morphologically the RV. The RVOT links with the AV. The PV does not exist in the chamber. The features confirm that the left side does not have a chamber, which is equivalent to a single ventricle with right ventricular morphology. AV aortic valve, RA right atrium, RV morphological right ventricle, RVOT right ventricular outflow tract, TV tricuspid valve. (d) Specimen 1100. Exposure of the aortic valve orifice and subvalvular myocardial infundibulum. AV aortic valve, CS coronary sinus, RA right atrium, RV right ventricle. (e) Specimen 1100. Exposure of the left atrium without the mitral valve. a, atrial septal defect; b, left atrial appendage; c, rupture of the coronary sinus; LA left atrium, RA right atrium. (f) Specimen 1100. Mitral atresia. No MV is found in the LA. The bougie indicates the residual recess. The ventricular wall under the atrium belongs to the morphological RV (RV wall). AO aorta. (g) Schematic diagram of specimen 1100. The ventricle has structures characteristic of the RV. The RA has inlets of the coronary sinus and the vena cava. These features prove the atrium is in situ solitus. The mitral atresia remains a recess without a LV chamber