This study was undertaken to analyze the effect of diltiazem blood cardioplegia (D-BCP) in patients of valvular heart disease with severe left ventricular dysfunction (EF = 56.3%, FS = 26.0%, CI = 2.241/min/m3), they were satisfied with NYHA functional class 3 and 4, also cardiothoracic ratio over 65%. By negative choronotropic action of D, the heart rates in D added group tend to be less than those of D free group 4 to 16 hours postoperatively, although that may diminish the incidence of ventricular arrhythmia postoperatively. D-BCP improved better functional recovery (mPAWP-LVSWI relation) during the early postoperative period than those seen in preoperatively. The pulmonary vascular resistance index of D added group showed significantly lower levels than those in the preoperative period, 0 to 16 hours after surgery. Consequently, D-BCP might be safe and provide superior protection for severe valvular heart disease.