A 70-year-old man with New York Heart Association class III symptoms and a diagnosis of pulmonary hypertension presented for right and left heart catheterization. A large atrial septal defect with a shunt ratio (pulmonary to systemic blood flow) of 3.4, a persistent left-sided superior vena cava draining into a giant coronary sinus and moderate pulmonary hypertension was diagnosed at right heart catheterization. Marked V waves were seen in the left atrial tracing, which were absent in the right atrial tracing demonstrated on a pullback tracing (arrows in Figure 1A). No mitral regurgitation or ventricular septal defect was seen to account for the left atrial V wave. A transesophageal echocardiogram demonstrated a large (3.5 cm) secundum atrial septal defect (ASD) (Figure 1B; arrow), and a moderate to severe, highly eccentric tricuspid regurgitation with prolapse and thickening of the anterior tricuspid valve leaflet. The jet of tricuspid regurgitation was directed across the giant ASD into the left atrium, accounting for the giant V wave in the left atrial tracing (Figure 1C). Eccentric tricuspid regurgitation across an ASD is a novel explanation for a left atrial V wave, demonstrating the usefulness of multimodality imaging when clarifying hemodynamics. The patient is stable and awaiting surgery for ASD closure and tricuspid valve repair/replacement. Figure 1) ASD Atrial septal defect; TR Tricuspid regurgitation