An esophageal monitoring device includes a camera and, optionally, one or more lights to enable visualization of an interior of a subject's esophagus. Visualization of the interior of the subject's esophagus before and after a left atrial ablation procedure may enable a healthcare provider to determine whether or not the left atrial ablation procedure has damaged the subject's esophagus before the subject experiences any symptoms of such damage. An esophageal monitoring device may also include sensors and/or markers that enable a determination of its location within a subject's esophagus. Such an esophageal monitoring device may be configured for three-dimensional mapping, and enable the generation of an accurate three-dimensional map of the physical relationship between a subject's esophagus and the left atrium of his or her heart. Methods of monitoring a subject's esophagus while a left atrial ablation procedure is being conducted on the subject's hear are also disclosed.