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 the pH buffering agent. METHODS: Sixty patients being applied Histidine Buffered Solution (HBS) (n = 27) or Cold Blood Cardioplegic solution (CBC) (n = 33), both at 4 degrees C, were studied prospectively. Pre- and post-bypass left-ventricular (LV) volume was measured by echocardiography. With a ventricular pressure catheter, LV pressure-volume loops were constructed to determine the slope of the end-systolic pressure-volume relationship (Emax) without inotropes. RESULTS: There were no postoperative deaths in either group. Thirty minutes after reperfusion Emax was significantly better in the HBS group than in the CBC group (6.0 +/- 1.0 mmHg/cm3 vs 3.7 +/- 0.8 mmHg/cm3). Cardiac Index was also significantly higher in HBS group than in CBC group with lower inotropic requirement. Homologous blood transfusion was avoided in 64% of the patients receiving HBS versus 48% of the patients with CBC. CONCLUSIONS: We conclude that the new histidine-buffered cardioplegic solution provides effective protection with excellent recovery of pump performance in clinical open heart surgery.