Radiologic notes in cardiology. Angiographic differentiation between tetralogy of Fallot and double-outlet right ventricle. Relationship of the mitral and aortic valves.

common atrium into the primitive left ventricle, which must empty across the incomplete ventricular septum into the right ventricle. The only channel of egress from the heart is the bulbus (conus) cordis, connecting the right ventricle with the truncus arteriosus. Both the pulmonary artery and the aorta eventually form from the truncus. In other words, both great vessels, in essence, arise from the right ventricle at this stage in development. Where the cardiac tube is bent most sharply, its wall becomes folded upon itself and results in a ridge of embryonic tissue that projects into the lumen. This ridge lies at the junction of the bulbus and the right ventricle and is called the bulboventricular flange (fig. 1). As the heart matures, this flange is resorbed and is not represented in the adult heart. The bulbus is divided in two by the growth of opposing ridges of mesenchymal tissue which join to form the conus septum. The cardiac end of the septum joins the ventricular septum, while its upper end becomes continuous with a similar septum dividing the truncus. The anterior channel of the conus connects the right ventricle with the pulmo-