Triple atrial heart 1. Triple atrial heart is a rare congenital cardiovascular malformation, which refers to an abnormal septum-like structure in the atria that divides the atria into two chambers, and can be divided into left atrial triple atrial heart and right atrial triple atrial heart. The clinical term “triple atrial heart” generally refers to the left atrial triple atrial heart. The left atrium is divided by an abnormal fibromuscular septum into two parts: the posterior superior appendage (connected to the pulmonary vein) and the anterior inferior part of the innate atrium (connected to the mitral valve). Because the septum constitutes a resistance to left atrial blood flow, the appendage is significantly enlarged and the left ventricular blood flow is relatively low, resulting in hemodynamic changes similar to those seen in mitral stenosis; this malformation can exist alone or is often combined with other malformations, most commonly atrial septal defect or complete ectopic pulmonary venous drainage. Anatomy and typing of cases 1, the paratrial and true atria are connected (typical triatrial heart): can be divided into those without other connections; with other abnormal connections, directly connected to the right atrium (i.e., combined atrial defect); with abnormal connections, ectopic drainage of the whole pulmonary vein. 2, paratrial and true atrial inaccessibility: directly connected to the right atrium (i.e., combined atrial defect); ectopic drainage of the whole pulmonary vein. 3.Incomplete three-atrial heart: part of the pulmonary veins are connected to the true atrium through the paratrial and the rest of the pulmonary veins are connected to the true atrium; part of the pulmonary veins are connected to the true atrium through the paratrial and the rest of the pulmonary veins are ectopically draining; part of the pulmonary veins are connected to the right atrium through the paratrial and the rest of the pulmonary veins enter the true atrium normally. Once the diagnosis of triple atrial heart is established, surgical treatment is the only method. Adequate resection of the septum under extracorporeal circulation is required, along with repair of the septal defect and correction of other combined intracardiac malformations.