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

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.

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.

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.

We conclude that the new histidine-buffered cardioplegic solution provides effective protection with excellent recovery of pump performance in clinical open heart surgery.