The existence of the complication of arterial dissection or rupture caused by the arterial perfusing cannula used for extracorporeal systems has been recognized for some time but has been infrequently referred to in the literature. Jones et al reported a 3.2% major complication rate directly related to arterial cannulation.1 Included in their analysis of 125 patients was a case of retrograde dissection of the aorta with rupture at the time of operation into the pericardium. The occurrence of a case of retrograde dissection with subsequent spontaneous decompression by rerupture into the thoracic aorta but with catastrophic occlusion of the celiac, left renal, superior mesenteric, and inferior mesenteric arteries has prompted us to describe this case in some detail in order to further focus attention upon this complication and its possible prevention. Report of Case A 51-year-old man was admitted to the Hospital of the University of Pennsylvania on Oct