Transposition Of Great Arteries Lead To Pulmonary Hypertension, The Molecular Mechanisms And Clinical Efficacy Of The Middle Of The Arterial Switch Operation

PartⅠ:Molecular mechanisms of pulmonary hypertension in complete transposition of the great arteries combined with ventricular septal defectObjective:we sought to explore the reversibility and potential molecular mechanisms of pulmonary hypertension in patients with complete transposition of the great arteries(cTGA) combined with ventricular septal defect(VSD) in comparison with those with simple VSD.Methods:Twenty-four patients with pulmonary hypertension(mean pulmonary arterial pressure greater than 30mmHg) were enrolled in our study,in which 10 patients suffered from cTGA with VSD,and the rest 14 patients suffered from simple VSD.Lung specimens were taken from the right middle lobe of lung before cardioputmonary bypass.The extent of pulmonary hypertension was then graded according to the Heath-Edwards classification.ELISA was used to examine the expression of eNOS,iNOS,ET-1,ET-AR,ET-BR, MMP-2,MMP-9 and TIMP in all the specimens.Result:There were no statistically significant differences in age,height,weight,the size of VSD,and the pulmonary artery pressure before operation between the groups.The level of hemoglobin,aortic and pulmonary arterial oxygen saturation,and the reduction value of postoperative pulmonary arterial pressure were significantly higher in cTGA patients(p＜0.05).All the patients had grade 0-3 Heath-Edwards changes on lung biopsy samples.The expression of eNOS and MMP-2 was significantly lower in the TGA group than that in the simple VSD group(eNOS:280.13±101.92ng/mg vs 488.41±249.6 ng/mg,p＜0.05;NMP-2: 31.68±15.36ng/mg vs 69.28±49.12ng/mg,p＜0.05).There were no statistically significant differences between the two groups regarding the expression of iNOS,ET-1,ET-AR,ET-BR,MMP-9 or TIMP.Conclusion:The imbalance of the NOS/ET system and the MNP/TINP system involves in the development of pulmonary hypertension in patients with TGA combined with VCD.In patients with cTGA,the high oxygenation state in pulmonary circulation may decrease the expression of MNP2 and eNOS,and may affect the progress of pulmonary hypertension to a certain extent. PartⅡ:middle term outcome of the arterial switch operation:predictors and functional evaluationObjectives:The aim of this report was to study the middle outcome in terms of follow-up mortality,predictors for late pulmonary stenosis(PAS) and insufficiency of the neo-aortic valve(neo-AVI) in patients with transposition of the great arteries(TGA) and Taussig-Bing malformation undergoing arterial switch operation(ASO).Materials and methods:Between January 2004 and December 2007,169 patients(129 male,40 female;mean age 11.71±26.3 months) with TGA or Taussig-Bing malformation underwent ASO.The patients were divided in GroupⅠ(n=56)-TGA with intact ventricular septum and GroupⅡ(n=113)-TGA with ventricular septal defect (VSD).All the patients were followed up in out-patient department by ultrasonic cardiogram.The mean follow-up periods was 27.66±14.6 months.Multiple logistic regression analysis was performed to find out the risk factors.Results:The overall hospital mortality was 11.24%(19/169)and there was no significant difference between GroupⅠandⅡ.The multivariate analysis revealed age above 6 months as strong predictors for poor postoperative survival.Predictors for neo-AVI were complicating VSD,age＞6 months and postoperative neo-AV Z-score＞1.Predictors for moderate-to-severe PAS were age＜1 months and pulmonary artery plasty.Conclusion:ASO remains to be the optimal choice for the treatment of various forms of TGA with acceptable middle outcome in terms of overall survival.Patients with TGA should be treated as early as possible,age＞6 months is predictors for poor postoperative survival and neo-AVI.Mismatch between the neo-aortic root and distal aorta induce neo-AVI.Unstretchable patch in pulmonary artery plasty induce PAS.