Objective: The aim of the study was to assess the safety and efficacy of a normothermic cardioplegia solution N trademark use and obtain additional information about dosing regimens during normothermic or mild hypothermic cardiac surgery. Methods: A retrospective observational study included 150 cardio surgery patients. The primary endpoint was the intraoperative acute heart failure development. The secondary endpoints were the postoperative Troponin T concentrations, the need for catecholamine support, and the repeated infusion of a cardioplegia solution. Results: The duration of aortic cross-clamping varied from 17 to 154 minutes, median 59 [interquartile range, 46 - 73] minutes. Spontaneous sinus rhythm recovery was observed in 136 (90.7%) patients. Intraoperative acute heart failure was observed in 1 case. The Troponin T concentrations were 0.331 plus-or-minus sign 0.143 ng/mL after surgery. Mortality was 2% (3 patients). Eight patients received an additional volume of N trademark solution to maintain asystole. Among 16 patients with a cross-clamp duration greater than 90 minutes epinephrine was used in 3 (18.8%) patients in doses of more than 0.05 mcg/kg/min. Among 134 patients cross-clamp duration less than 90 minutes the catecholamine support was used in 4 (3%) patients, p=0.027. Conclusions: A primary single-dose infusion of cardioplegia solution N trademark provides myocardial protection for 59 (interquartile range, 46-73) minutes and up to 154 minutes. The catecholamine support in the group of aortic cross-clamp duration less than 90 minutes was used lesser than in the group of aortic cross-clamp duration greater than 90 minutes (3% and 18.8%, respectively). The cardioprotection during cardiopulmonary bypass surgery especially in elderly patients with concomitant disease needs to be confirmed in future investigations.