Objective: to describe the surgical technique for correcting cor triatriatum through actual photos and video of the intervention. Methods: a literature review, illustrated with images of the actual anatomy of this pathology in an intervention performed on a 68-year-old female patient who consulted for dyspnea and was diagnosed with cor triatriatum sinister. Results: An illustrated surgical intervention of cor triatriatum sinister in an adult patient, with functional class recovery. Conclusions: The objective of cor triatriatum surgical treatment is to restore a normal cardiac anatomy, as well as correct associated anomalies that are frequently present in this condition.