The Experimental study for establishment of safty cargioplegia in neonatal open heart surgery

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Protection of the ischemic myocardium has been a major problem with open heart surgery in the neonate. Although University of Wisconsin (UW) solution is effective for the preservation of other organs, its protective effects are reduced in hypothermic conditions between 15-20 ﾟC,which is the typical temperature during open heart surgery. As this reduction in efficiency is due to the high potassium concentration of UW solution, we developed a lowpotassium version of UW solution (LPUW), replacing most of the potassium ions with sodium ions and making the concentration of potassium and calcium the same as in St. Thomas's Hospital cardioplegic solution No.2 (STS) (K : 16 mM,Ca : 1.2 mM). Recorery of cardiac function from hypothermic ischemia between 15-20 ﾟC was tested in isolated hearts from newborn rabbits (day 3-6) perfused with LPUW and results were compared with those obtained using conventional high-potassium UW solution and STS.Modified Krebs-Henseleit bicarbonate buffer (KH) was use … More d to represent hypothermia alone. After perfusing in the working mode for 30 minutes, the isolated heart was injected and arrested with one of the four cardioplegic solutions. Ischemia was maintained for either 180 minutes at 15 ﾟC of 360 minutes at 20 ﾟC (a total of 8 groups, each consisting of 7 samples). Subsequently, the heart was perfused again for 15 minutes in Langendorff mode and 30 minutes in the working mode. Hemodynamic parameters were recorded before and after the arrest, and subsequently compared. Percent recovery of aortic flow after ischemia for 360 minutes at 20 ﾟC was 40.3(]SY.+-。[)113.3 %, 79.3(]SY.+-。[)10.0%, 64.3(]SY.+-。[)11.9%, and 43.9(]SY.+-。[)15.9% (mean (]SY.+-。[) standard deviation) for HPUW,LPUW,STS,and KH,respectively. LPUW demonstrated the most favorable protective effects among the four solutions (p<0.05), while HPUW demonstrated significantly worse protection compared with LPUW and STS (p<0.01). In the case of ischemia for 180 minutes at 15 ﾟC,a similar tendency was observed, although no significant difference was observed between LPUW and STS.Concentrations of adenosine triphosphate and creatine phosphate in the cardiac muscle after ischemia tended to be higher with LPUW,although no significant difference was observed between LPUW and STS.In conclusion, LPUW solution was superior to conventional UW solution with regard to recovery from hypothermic ischemia between 15-20 ﾟC of the isolated heart from neonate rabbit. This observation supports the clinical application of LPUW solution for open heart surgery in newborn patients. Less