Coconut atrium: transmural calcification of the entire left atrium.

Massive calcification of the left atrium usually spares the interatrial septum, which provides a cleavage plane for surgical access to the mitral valve. Endoatriectomy with mitral valve replacement is the currently accepted corrective procedure because it affords maximum exposure while decreasing the risk of embolization and intraoperative hemorrhage. We describe a case in which the entire left atrium, including the septum, was thickly calcified and resembled a coconut shell.