| BackgroundCardiac transplantation is one of the most effective treatments of end-stage heart disease, but there are still a lot of problems unsettled, the primary limitation is the serious shortage of donor heart. Because of the lack of donor heart, tens of thousands of patients die while awaiting cardiac transplantation. Even some patients who accepted the heart transplantation may die or have to accept another heart transplantation owing to the heart failure which always following the long time ischemia and ischemia/reperfusion injury. There are two main reasons for the shortage of donor heart:first, the number of the donor heart grafts which can meet the clinical criteria are limited; second, the donor heart graft's safety preservation time is very short.For many years, cardiac transplantation has represented an established procedure using the so-called'Traditional Criteria'for an appropriate heart transplant donor as suggested by Copeland et al., which means that the appropriate donor heart must come from the brain death and heart beating donor. However, over the past two decades, there has been a considerable increase in the number of patients annually listed for cardiac transplantation, and strict adherence to the'standard donor criteria' resulted in a serious undersupply of available organs with the result of significantly extended waiting time and increased mortality on the waiting list. Thence, the need for continual extension of donor selection criteria to meet the demand for heart transplantation is leading to increasing acceptance of marginal donors. The use of non-heart beating donors is one of the most perspective aspects of the using of marginal donors, which also is a potentially effective approach to increasing the donor pool.The research of heart preservation mainly focuses on two points:improve the heart preservation solution and the method of heart preservation. At the beginning, researchers found that high concentration of potassium could help cardiac arrest very fast; but during the subsequent research they fund that too high concentration of potassium could hurt the endothelium. Then, many other kinds of heart preservation solution have been produced, such as ST. Thomas solution, UW solution, HTK solution et al. which could supply much more safely preservation result. However, these solutions still have one very serious shortage that they can not delivery enough oxygen. For this reason, the blood cardioplegia was introduced, which is much more similar with the physiological state, and had showed a perfect effect for heart preservation. The former researchers had tried quite many different ways to preserve the donor heart grafts, for example simple cold static immersion, continual low flow perfusion, hypothermia oxygenation solution perfusion, coronary oxygen persufflation, ischemic preconditioning et al.. The hypothermia oxygenation solution perfusion can continually supply oxygen to the myocardial tissues, maintain the aerobic metabolism of myocardial cells, reduce the intracellular acidosis which comes from the anaerobic metabolism, and also provide sufficient energy substrate to the myocardial tissues. It had showed an ideal result in heart preservation.Materials and Methods1,24 healthy Swedish domestic pigs were randomly divided into two groups, then the pigs each group were randomly divided into donor group and receptor group into groups. Pigs were premedicated with an intramuscular injection of 15mg/kg ketamine hydrochloride and 2mg/kg xylazine. An ear vein was cannulated and anesthesia was induced with ketamine hydrochloride and pancuronium bromide by pumped intravenous injection. At the same time, an endotracheal tube was inserted and mechanical ventilation begun. All the donors were collected non-leukocyte blood, induced heart warm ischemia models and harvested the heart after 10 minutes warm ischemia.2,All the donor heart grafts were preserved in a micro-flow perfusion system with 4℃blood Plegisol solution for 8 hours in the micro-flow perfusion group. All the donor heart grafts were immersed in the 4℃Plegisol solution for 8 hours in the control group. Shumway orthotopic heart transplantation was performed in both groups. Warm blood Plegisol solution perfusion was performed during the implantation phase in the former group and kept the thoracic cavity in 4℃with cold saline in the latter group.3,Observed the resuscitation of hearts, measured the HR, the MAP, the CO and the CF; detected myocardial protein (cTnT,Mb) from the blood sample which was collected from the vein and determined the percentage of water content and took histopathologic study after the orthotopic heart transplantation.Results1. The resuscitation of hearts:4 hearts got sinus rhythms while 2 hearts got ventricular fibrillation but could get sinus rhythms after defibrillation in the micro-flow perfusion group.1 heart got sinus rhythms while 4 hearts got ventricular fibrillated and 1 heart kept a ventricular fibrillated rhythm.2. Hemodynamics:The heart rate in the micro-flow perfusion group (106.5±10.99) bpm without significant difference from the control group (104.27±5.05)bpm(P>0.05). The mean arterial pressure, the cardiac output and the coronary flow in the micro-flow perfusion group (71.52±3.37) mmHg, (2.34±0.05) L/min, (91.07±3.86)ml/min were significantly higher than that in the control group (56.15±3.21) mmHg, (1.87±0.08)L/min, (77.61±3.20) ml/min (P<0.05).3. The myocardial protein (cTnT,Mb) in the micro-flow perfusion group were significantly higher than the control group(P<0.05). The water content in the micro-flow perfusion group (80.17±0.39)% had no significant difference from the control group (79.93±0.39)%(P>0.05). Histopathologic damage in the micro-flow perfusion group was more severe than the control group.Conclusions1. Bloody Plegisol solution can reduce the degree of hypoxia with the donor heart in the cold ischemia period and mitigate the damages caused by hypoxia.2. The system of hypothermic micro-flow continuous perfusion, which is superior to the immersion with hypothermic Plegisol solution, can prolong the period of the donor heart preservation safely.3. The heart from NHBD caused by ischemic shock, after hot ischemia for ten minutes, could still be in clinical use as the heart transplant donor. |
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