Charanjit S. Rihal et al. JCIN 2012;5:121-130 Device Sizing for Oblong Defects Three-dimensional echocardiogram of mechanical valve prosthesis shows an oblong defect. Successful closure of the defect with a single device requires a relatively large occluder, which increases the risk of prosthetic impingement due to device overhang. Closure with multiple smaller occluders (circled in red) can result in procedural success with a lower risk of prosthetic impingement. Charanjit S. Rihal et al. JCIN 2012;5:121-130 American College of Cardiology Foundation