The incidence of pericardial effusion and late cardiac tamponade after aortic and valvular surgery is higher than after other cardiac surgical procedures. The aim of this study is to evaluate the clinical safety and efficacy of prolonged mediastinal drainage using small, soft silastic drains (Blake drain, Ethicon USA) versus conventional mediastinal drainage using large chest tubes. Patients undergoing aortic and / or valvular surgery will be randomized in two groups. In group A, mediastinal drainage will be accomplished using a 28F or 32F chest tube in the anterior mediastinum and a 19F Blake drain located in the posterior pericardial cavity. In group B, mediastinal drainage will be accomplished using two 28F or 32F chest tubes located in the anterior mediastinum. In both groups, conventional chest tubes will be removed on the first postoperative day, while patients in the group A will have prolonged drainage using the Blake drain until output is less than 50 ml over 24 hour. Patients will be followed during their postoperative course for occurrence of significant pericardial effusion as detected on routine echocardiogram and late cardiac tamponade requiring reintervention.