Fibrin deposition on the nonflow surface of a valve can cause stenosis.

Subvalvular pannus can cause stenosis, and pannus can cause regurgitation by retracting leaflets.

Pannus may be difficult to appreciate on echocardiography unless extensive or combined with thrombus.

Primary perforations or tears can result in eccentric regurgitant jets.

Endocarditis must be excluded in cases of thrombosis or leaflet tear.