Below are three video clips showing: (1) The presence of cor triatriatum in the left atrium is shown by a portable echocardiogram machine at the apical four-chamber view; (2) Flow accentuation across the fenestration in the cor triatriatum is shown by a standard echocardiogram machine at a modified apical four-chamber view; and (3) The presence of cor triatriatum is shown by transoesophageal echocardiogram at midoesophageal long-axis view