The Role Of Valve-associated Hemodynamics In Aortic Dilation Of Patients With Bicuspid Aortic Valve

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Association Between Bicuspid Aortic Valve Phenotype,Type of Valvular Dysfunction and Aortic ConfigurationObjective:To investigate the association between bicuspid aortic valve(BAV)phenotype,type of valvular dysfunction and aortic configuration.Methods:We retrospectively reviewed 407 patients of BAV with thoracic computed tomography angiography(CTA),who had undergone aortic surgeries from February 2011 to January 2016.BAV phenotypes,aortic valve lesion types(combining BAV phenotypes and the types of valvular dysfunction),and clusters of aortic configuration were categorized separately.Then,the association between BAV phenotypes and types of valvular dysfunction,as well as the association between types of aortic valve lesion and aortic configurations were evaluated.Results:There was close association between BAV phenotypes and the types of valvular dysfunction(p<0.01).Valvular regurgitation was more frequently in Type-1 LR,whereas valvular stenosis in Type-0 LAT.For Type-1 RN,more patients who suffered from aortic valve stenosis combined with regurgitation were observed.After that,the significant association between aortic valve lesion types and the clusters of aortic configuration were revealed(p<0.01).In Type-1 LR,valvular stenosis tended to exhibit ascending aorta(AAo)dilation alone,but regurgitation more frequently showed as aortic root dilation(AoR)and AAo dilation.Patients of Type-0 LAT with stenosis were more frequently presented with aortic dilation with AAo and proximal aortic arch.Conclusions:In BAVs(Type-1 LR and Type-0 LAT)with valvular stenosis,aortic dilation was more localized to AAo/AAo+PArc,indicating the hemodynamic turbulence theory.Insufficient BAV(Type-1 LR)were associated with a more extensive aortic dilation(AoR + AAo),supporting a more aggressive inherent-disposed aortopatlhy.Part ? The Follow-up Study on Proximal Aortic Arch Dilation in Patients with Stenotic Bicuspid Type-0 LATObjective:In this study,we followed patients with stenotic BAV(Type-0 LAT)who had undergone wheat's operation without hemiarch repair,in order to investigate whether PArc dilation continued after surgery.Methods:All of the patients had undergone thoracic CTA examination before and after surgery.3-dimensional reconstruction of CTA was used to measure the diameters of aorta.The diameters of PArc in follow-up were compared with those pre-operation.Results:The late follow-up period was between 6 and 26 months(mean,17.50±5.89 months).The mean pre-operative diameter of PArc was 44.33±3.25mm,and the mean diameter in follow-up was 39.42±2.41mm.Significant difference(p<0.001)was found in the diameter of PArc between pre-operation and follow-up.The diameter of PArc in follow-up is significantly less than those pre-operation.Conclusions:For stenotic BAV patients(Type-0 LAT)with dilation of AAo+PArc,there is no continuous expansion of PArc after wheat's operation.Hemodynamics may mediate the dilation of PArc in these patients.If the patients of stenotic bicuspid Type-0 LAT occurred with aortic dilation of AAo+PArc,we should less aggressively replace the dilation of PArc.Part ? Valve-Related Hemodynamics Mediate Ascending Aorta Dilation in Patients with Bicuspid Aortic ValveObjective:This study investigated the relationship between wall shear stress(WSS)and regional aortic tissue remodeling in stenotic BAVs(Type-1 LR and Type-0 LAT),and determined the impact of elevated WSS on the expression of matrix metalloproteinases(MMPs)and tissue inhibitor of matrix metalloproteinase-1(TIMP-1).Methods:Twelve patients underwent 4-dimensional flow cardiac magnetic resonance imaging(4-D Flow CMR)to evaluate aortic WSS before surgery.Paired aortic wall samples(regions of maximal and minimal WSS)were collected from all cohort patients during wheat's operation.Aortic medial elastin degeneration was quantified by histology image analysis and extracellular matrix regulation by matrix-related protein expression.Results:Histological analysis of aortic tissue demonstrated significantly decreased elastin content and architecture consistent with aortopathy in all patients.The mean thickness of elastin fibers was found significantly decreased in aortic wall(p<0.001)that exosed to maximal WSS(3.40±0.69?m)compared with aortic wall from the region of minimal WSS(5.52±0.85?m).The mean distance between elastin fibers was significantly greater(p<0.001)in regions of maximal WSS(32.12±5.83pm)than in those of minimal WSS(23.33±3.81?m).The analyses of extracellular matrix regulatory molecules showed that aortic wall subjected to minimal WSS demonstrated significantly increased protein expression of MMP-1(p<0.01)and MMP-3(p0.037).However,we did not find the association between WSS and the expression of MMP-2(p=0.066)and TIP-1(p=0.986)in paired aortic wall.Conclusions:Regions of elevated WSS correspond with aortic medial tissue remodeling.Valve-related hemodynamics may play an important role in the development of ascending aorta dilation in stenotic BAVs(Type-1 LR and Type-0 LAT).