In neonates and children the blood vessels are small in calibre and the correct choice of arterial and venous cannulas together with accurate placement are crucial to avoid obstructing vascular branches,and misdirecting flow or impairing venous drainage.Normally in children, to establish the cardiopulmonary bypass (CPB)one arterial cannula is inserted inthe ascending aorta,and single stagevenous cannulae, where two cannulae inserted into the superior and inferior vena cava and joined by the Y-pieceare used in the most open-heartsurgeries to facilitate the circulatory, respiratory support along with the temperature management. Rarely aortic cannulation can lead to aortic dissection, aortic posterior wall rupture leading to trauma to the esophagus, dislodgement of the aortic atheroma, fatal bleeding leading even to cardiac arrest. In addition, SVC and IVC syndrome can also occur due displacement or obstruction by the venous cannulae. However, repeated cardiac arrestsin childrenafter successful weaning from CPB,even with the use of an appropriate size aortic cannula has not been reported in the literature to date. We wish to discuss this fatal complicationafter weaning from CPB, due to aortic flow obstruction due to aortic cannula in a one-year-old, 5.5 kg child following successfulventricular septal defect(VSD) repair. The international review board approval or waiver and clinical trial registrations are not applicable for this case report publication