<prompt> Manifestations of acute dissection include all of the following exceptPericardial tamponadeARMRAMI  <response>: Ref Harrison 19 th ed pg 1640 Hemopericardium and cardiac tamponade may complicate a type A lesion with retrograde dissection. Acute aoic regurgitation is animpoant and common 50 complication of proximal dissection. An electrocardiogram that shows no evidence of myocardial ischemia is helpful in distinguishing aoic dissection from myocardial infarction 