Objective: To investigate whether the different concentrations of morphine after coronary perfusion have myocardial protection.
Subjects and method: Forty-five patients undergoing heart valve replacement were randomly divided into three groups of 15 patients: group A (morphine 2 μmol/L in the cardioplegic solution), group B (morphine 4 μmol/L in the cardioplegic solution) and group C (no morphine in the cardioplegic solution). The three groups were monitored before induction (T1), five minutes before (T2) and five minutes after (T3) cardiopulmonary bypass (CPB), perioperative (T4) for haemodynamic parameters, two hours after CPB (T5) and 24 hours after CPB (T6). The postoperation incidence of severe ventricular arrhythmia and low cardiac output, CPB transit time, aortic cross-clamp time, defibrillation time, duration of ventilation and intensive care unit (ICU) and hospital stay were recorded.
Results: The levels of cardiac troponin I (cTnI) at T5 and T6 in group A and group B were significantly lower than those in group C (p < 0.05), and at T6 in group B, were lower than those in group A (p < 0.05). The levels of CK-MB at T6 in group B were lower than those in group C (p < 0.05). The morphological changes in group A and group B were less than those in group C; and the least in group B.
Conclusion: Morphine at concentrations of 2 μmol/L and 4 μmol/L after coronary perfusion on cardiac valve replacement with CPB has myocardial protection; 4 μmol/L of morphine provides more myocardial protection.