Percutaneous drainage of a localized biatrial haematoma causing regional tamponade in a patient with prior coronary artery bypass graft surgery: a case report.

Prior coronary artery bypass grafting should not be considered protective from cardiac tamponade in patients in whom perforation occurs, because loculated effusions can develop beneath adhesions of the pericardium and compress various cardiac structures (such as the left atrium or the right ventricle); they appear several hours after the intervention and cause atypical haemodynamic manifestations.