Superior myocardial protection with a new histidine-buffered crystalloid cardioplegic solution in clinical trial

Background: Blood cardioplegia has been widely accepted in clinical cardiac surgery based on its excellent oxygen delivery and pH buffering capacity, To further conserve blood during clinical cardiac surgery, we formulated a new crystalloid cardioplegic solution containing histidine (100 mol/L) as t he pH buffering agent. Methods: Sixty patients being applied Histidine Buff ered Solution (HBS) (n = 27) or Cold Blood Cardioplegic solution (CBC) (n = 33), both at 4 degrees C, were studied prospectively. Pre- and post-by-pas s left-ventricular (LV) volume was measured by echocardiography. With a ven tricular pressure catheter, LV pressure-volume loops were constructed to de termine the slope of the end-systolic pressure-volume relationship (Emax) w ithout inotropes. Results: There were no postoperative deaths in either gro up. Thirty minutes after reperfusion Emax was significantly better in the H BS group than in the CBC group (6.0+/-1.0 mmHg/cm(3) vs 3.7+/-0.8 mmHg/cm(3 )). Cardiac Index was also significantly higher in HBS group than in CBC gr oup with lower inotropic requirement. Homologous blood transfusion was avoi ded in 64% of the patients receiving HES versus 48% of the patients with CB C. Conclusions: We conclude that the new histidine-buffered cardioplegic so lution provides effective protection with excellent recovery of pump perfor mance in clinical open heart surgery.