Defects can also open to the inlet of the right ventricle when they are part of an atrioventricular septal defect with a common atrioventricular valve. As shown in Figure 10A, when the superior and inferior bridging leaflets are attached to the leading edge of the atrial septum (yellow dots) in this setting, then shunting is possible only at the ventricular level. The ventricular component of the defect (red dots) is then the true ventricular septal defect of atrioventricular canal type. Figure 10B shows the left ventricular view of the same heart, with both bridging leaflets attached to the leading edge of the atrial septum (yellow dots). Note the atrial septal defect within the oval fossa, and the coronary sinus in the left atrioventricular groove.