Objective:To discuss the safety and effectiveness of del Nido cardioplegia solution in severe valvular surgery.Methods:A retrospective analysis of 138 patients of severe valvular disease underwent valve replacement or valvuloplasty in Hunan Provincial People′s Hospital between July 2019 and December 2020 was performed. According to the different cardioplegic solution used, patients were separated in two groups: the del Nido cardioplegia group (D group, n=73) and the St. Thomas cardioplegia group (C group, n=65). The perioperative clinical results of the two groups were compared to evaluate the safety and effectiveness of del Nido cardioplegia in the operation of severe valvular disease. Results:Preoperative characteristics were similar between the two groups, including gender, age, body weight, ejection fraction, and myocardial markers ( P>0.05). No statistical differences were noted in cardiopulmonary bypass time, clamp time, mechanical ventilation time, vasoactive drug use time, ICU and hospital stay time, and ejection fraction before discharge ( P>0.05). However, the times of cardioplegia perfusion [(1.33±0.47)times vs (4.08±0.48)times] and the total perfusion time [(3.96±1.41)min vs (13.15±1.46)min] in group D were lower than those in group C, while the automatic rebound rate (90.41% vs 76.92%) was higher than that in group C ( P<0.05). Both groups successfully completed the operation. There were no serious complications of important organs such as low cardiac output, brain, liver and kidney during and after the operation. There were no deaths during hospitalization, and all patients were cured and discharged. Conclusions:There was no significant difference in myocardial protection between del Nido and St. Thomas cardioplegia solution in severe valvular surgery. The application of del Nido cardioplegia could reduce the frequency of perfusions and total perfusion time.