RESUMEN

Introduction and importance: Cor triatriatum sinister (CTS) is an uncommon heterogeneous congenital cardiac defect that may manifest in adulthood when symptomatic blockage manifests due to a change in hemodynamic physiology or when a condition such as atrial fibrillation (AF) arises. The incidence of cor triatriatum with cardiomyopathy and congenital heart illness ranges from 0.1 to 0.4%. Case presentation: The Department of Cardiology examined a 10-year-old girl for a diastolic murmur. The patient's medical history was ordinary, and no previously known co-morbid illnesses were present. Pneumonia was the patient's original medical condition. A cardiac murmur was also discovered during the physical examination, and the patient was forwarded for more research. Physical examination revealed just a diastolic murmur, which was noteworthy. The patient's care plan includes routine echocardiographic monitoring. Since the deformity was not clinically significant, surgical repair was not advised. Clinical discussion: It is unclear what caused this flaw. A full, incomplete, or fenestrated septum may be the result of the common pulmonary vein failing to merge with the left atrium during embryonic development. The existence of a fibromuscular membrane, which separates the left atrium (LA) into two chambers-the proximal chamber receiving the pulmonary veins (PVs) and the distal chamber contains the mitral valves and LA appendages defines the disease. Conclusion: The diagnostic procedure should be carried out in the optimal settings, however, in cases of frail health systems, employing accessible alternatives might help the early diagnosis. Early referral to a cardiologist is required in case of CTS suspicion.