Absent Right Superior Vena Cava

A 63-year-old man was referred for cardiac evaluation after a chest radiograph for an upper respiratory tract infection demonstrated prominent mediastinal borders (Figure 1). He had a normal clinical examination. A dilated coronary sinus was identified on transthoracic echocardiography. On subsequent transesophageal echocardiography, agitated saline contrast injected into the left antecubital vein first appeared in the coronary sinus, consistent with a persistent left-sided superior vena cava (Figure 2A and Movie 1). Interestingly, saline injected into the right antecubital vein also first appeared in the coronary sinus (Figure 2B and Movie 2). Imaging of the atria confirmed the absence of a right superior vena cava (Figure 2C). Cardiovascular MRI demonstrated that blood from the right side of the body passed via an innominate vein, anterior to the aortic arch (Figure 3A), to the …