Myocardial Protection Of Intermittent Warm Blood Cardioplegia In Valve Replacement

Warm heart surgery has become popular today, but CBC still remains most important method of myocardial protection in valve replacement. Though CWBC has been confirmed to have good results, it is hard to be used because' of its complicated operating and a vague bloody sight. Further more, it bring about activation of leucocytes and platelets, hyperkalemia and hemodilution. The effect of IWBC is still controversial and the attemption of IWBC is restricted in AVR. The aim of this study is to assess the application of IWBC by examining the difference in myocardial protection provided by IWBC and ICBC duringcardiac valve replacement.36 patients undergoing valve replacement from the department of cardiovascular surgery of Xijing hospital were randomly allocated into two groups: (1) intermittent warm blood cardiaplegia (n = 18) and (2) intermittent cold blood cardiaplegia (n = 18) . The demographic data were comparable between the two groups.Patients from both groups were purfused with 4:1 blood hyperkalemia cardioplegia .The concerntration of K+ was 16?0 mmol L-1 In group IWBC, the nasopharyngeal temperature was controlled in 34 ?5℃ with the cardioplegia of 32 ?5℃ , while in group ICBC the nasopharyngeal temperature was 30?1 ℃ with the cardioplegia of 10?4℃. For the first purfusion the dosage was 10?5mL kg-1. After that both the dosage and the potassic concerntration of the cardioplegia were reduced to the half of their origin. In group IWBC, purfusion was given every 15 minutes while in group ICBC the interval was no longer than 20 ?30 minutes.We recorded the aortic clamp time, the assist circulation time, the incidence of spontaneous resuscitation, ventricular arrhythmia and postoperative low-output syndrome. Coronary sinus blood samples from patients undergoing mitral valve replacement were collected and analyzed for lactate right after removal of the clamp. Arterial blood samples were taken before CPB, 30min, 6h and 24h after removal of the clamp for determination of cTnI. Myo-cardium of right atrium from some cases was obtained before and 30 min after the removal of the clamp for ultrastructural assessment. Mitochondrial scores were calculated.In this study, Group IWBC had shorter assist circulation time(15+5min vs 23+4min, P<0.05) and a higher incidence of spontaneous resuscitation, though the latter was not of statistical significance. The lactate level was significantly high in group IWBC(5.1 +0.6 mmol L-1 vs 2.8 + 0.5 mmol L-1, P<0. 05). There was no significant difference in serum cTnl concentration. As to the myocardial ultrastructural changes, both groups showed mild reversible damage. The difference of mitochondrial scores between the two groups was not significant.In short, IWBC can be operated easily, cost less time, and has similar effect to ICBC on myocardial protection, thus we can conclude that IWBC is of considerable value during cardiac valve replacement.