The invention relates to medicine, specifically to heart surgery, and can be used for protecting the heart from ischaemia during blood cardioplegia under normothermic conditions, and also under hypothermic conditions. A universal cardioplegic solution comprises the following, which are pharmaceutically acceptable: potassium ions magnesiumions a base and an acid, setting a pH buffer within a range of 7.1 - 8.9 and a diuretic, setting the osmolarity within a range of 275-460 mOsm/kg. The solution is used for maintaining heart function under conditions of artificial blood circulation, inter alia for both achieving and maintaining asystole. A method for using the universal cardioplegic solution provides for a transition, once asystole is achieved, to maintaining asystole by reducing the speed of supply of the starting components of the solution relative to the speed of supply of autologous blood, thereby reducing the ratio of components of the solution to autologous blood.
