The Application And Significance Of Computational Fluid Dynamics In Clinical Surgery Of Bicuspid Aortic Valve Patients

Objective:Bicuspid aortic valve has a high morbidity and mortality complication of aortic valve dysfunction,aortic dilatation,aortic aneurysm,and dissection.Previous studies have shown that these complications related to abnormal hemodynamic of ascending aorta,but the pathogenesis is not fully elucidated.This study aim to:?1?distinguish hemodynamic differences related to bicuspid aortic valve morphology,its complications and surgery.?2?Analyse the relationship between hemodynamic improvement and disease prognosis by comparing the pre and post hemodynamics in BAV patients after aortic valve operations.?3?Demonstrate the evidence of bicuspid aortic valve associated with abnormal hemodynamic environment and aortopathy.Methods:From January 2015 to January 2018,15 patients were accepted according to include and exclude criterion in the First Affiliated Hospital of China Medical University.All patients were classified to two groups according to surgery performed?aortic valve repair and non-repair of aortic valve?.Control group contain 5healthy..Assembled these patients preoperative thoracic artery CTA and collected rechecked postoperative thoracic artery CTA before out of hospital.Using computational fluid dynamics to simulation patients ascending aorta blood flow.Distinguish hemodynamic differences?flow angle,systolic peak velocity,region wall pressure and WSS?between bicuspid aortic valve morphology,aortopathy and surgery.Compare with 4 patients after aortic valve repair and David's operation and 2Wheatoperationpatientshemodynamicsimprovementbetweenpreand post-operation to explain disease prognosis.Results:The blood flow of majorities BAV patients are right helical eccentric jets pattern.This abnormal blood flow gained high helical angle,eccentric degree and systolic peak velocity in RL-BAV.The mainstream aortopathy of BAV patients is type2?60%?,main distribution in RL-BAV?46.7%?,next by type 3 Aortopathy?40%?.The anterior blood flow velocity of RL-BAV at S₂ and the blood flow velocity of Lat-BAV anterior,posterior and left wall at S₁ and anterior,right wall at S₂ less than control group.There was a positive correlation between the posterior blood flow velocity and aortic diameter at S₂ of the BAV patients.There was a negative correlation between the velocity of blood and aortic diameter at S₃ and S₄ of the BAV patients.The WSS of the RL-BAV patients greater than the control group.Only the velocity of blood of anterior,right wall at S₁and S₃,the velocity of blood of right wall at S₂ and the blood flow velocity at S₄ was significant difference from control group.The WSS of anterior,right wall at S₃ of Lat-BAV greater than control group.There was a positive correlation between the WSS of anterior wall and diameter at S₁ of the BAV patients.There was a negative correlation between the WSS and diameter at S₃and S₄of the BAV patients.The local wall pressure of the BAV patients greater than control group but no statistic significance?rang form 24.35 to 37102.9 Pa?.There was a positive correlation between the region wall pressure and diameter at S₁ and S₂.There have no significant correlation between the region wall pressure and diameter at S₃and S₄.Compare with 4 patients after aortic valve repair and David's operation hemodynamic differences between pre-and post-operation reveals flow angle improved,systolic peak velocity and region WSS increased in proximal aorta,while which was decreased in distal aorta and arches.Patients had increased systolic peak velocity and region WSS after Wheat operation in proximal aorta.All patients vessel wall pressure decreased after surgery.Artificial mechanical valve with 2 laminar jet patterns.Bioprosthetic valve also with a right handed helical flow pattern.Conclusion:The ascending aorta blood flow of healthy tricuspid aortic valve is an uniform velocity distributions with cohesive streamlines.While BAV patients ascending aorta blood flow is multi-species,mainly with right helical eccentric outflow jet patterns.The degree of eccentricity,helical angle and blood flow velocity were related to the classification of valve morphology.There was a significant positive correlation between regions wall pressure and the proximal aorta dilatation of BAV patients.There was a significant negative correlation between regions WSS and dilatation in distal aorta and arches.It is suggested that abnormal blood flow is an important factor causing aortic dilatation.Local wall pressure and WSS may be an important parameter to guide clinical surgery strategies.