Severe hypoxaemia after weaning from cardiopulmonary bypass: a case report.

Persistence of patent foramen ovale is frequent in adults and usually asymptomatic. We report the case of a patient in whom a patent foramen ovale was diagnosed after weaning from cardiopulmonary bypass and was not recognised preoperatively. Intraoperative transoesophageal echocardiography is pivotal for surgical decision-making and should be performed in all patients undergoing cardiac surgery.