Dissection of ascending thoracic aorta complicated by cardiac tamponade.

Two cases of cardiac tamponade caused by dissections of the ascending thoracic aorta are described. Despite uneventful induction of anaesthesia one patient exsanguinated following sternotomy and release of pericardial tamponade as the resulting increase in blood pressure caused aortic rupture. The second patient was managed with femoral-femoral bypass, propranolol and vasodilators prior to sternotomy to avoid this complication, and he survived. The anaesthetic management of a patient with cardiac tamponade is directed towards maintaining cardiac filling pressures and contractility. When the tamponade is released the sudden increase in cardiac output and blood pressure may cause the already weakened aorta to rupture.