Figure 7a. Intervenous saddle in a patient with normal pulmonary venous anatomy and accessory drainage of the right middle lobe. Bilateral VR images (endocardial view) from nongated multi-detector row CT show the intervenous saddles (solid white lines) between the right superior (RS) and right middle lobe (RM) pulmonary veins and the right superior and right inferior (RI) pulmonary veins (a), and between the left superior (LS) and left inferior (LI) pulmonary veins (b). The left inferior pulmonary vein intravenous saddle is also seen (dotted white line in b). Note the artifact from a pacer lead (arrows in a).