Cardiopulmonary bypass (CPB) is an essential requisite to facilitate cardiac surgery. Any malfunctioning in the aortic cannula or arterial system will produce neurological and other vital organs injury. The authors faced very high aortic line pressure during VSD patch closure under CPB. Early detection of high aortic line pressure needs strict vigilance and monitoring of CPB function. Prompt establishment of normal pump flow after normalization of line pressure along with brain protection methods may save the life of patient.