A case is described of an apparently healthy young woman in her first pregnancy who presented with acute pulmonary edema in the early postpartum period in the context of mild pregnancy-induced hypertension. After quick improvement in her condition, a Doppler followed by a transesophageal study revealed a left atrial septation with a small atrial septal defect secundum type and moderate mitral regurgitation strongly suggestive of a cor triatriatum sinistrum.