Heart bypass solution. Bag containing a solution that is used for cold crystalloid cardioplegia, a procedure that stops the heart beating so that there is no heart activity (asystole) during surgery. The cardioplegia solution contains chloride compounds and is applied directly to the heart through the aorta or coronary sinus. The cold crystalloid cardiaplegia method is considered the most successful, as it protects the myocardium heart tissue from damage or death during the operation.