Objective To explore the impact of different moving patterns during the dip-coating process on thickness distributions of polymer heart valves.Methods Based on the volume of fluid(VOF)multiphase flow model,the Eulerian wall-film(EWF)model,and dynamic mesh technology,the dip-coating manufacturing process of polymer heart valves were numerically simulated.The effects of vertical,horizontal,and circular moving patterns on flow characteristics of the surface impregnation liquid and liquid film distributions under self-rotation conditions of the models were mainly studied.Subsequently,seven identical test points were set on each valve leaflet to collect thickness data,and the coefficient of variation(CV)was calculated to evaluate the uniformity of the liquid film thickness.Given that the vertical and horizontal patterns had fewer moving planes,limiting the optimization space,the circular pattern(45°)with richer moving planes was selected as the basis for optimization,and comparative analysis of numerical simulation was conducted.Results In the vertical pattern,the peak CV was 0.461 3;in the horizontal pattern,the CV was 0.060 8;and in the circular pattern,the CV at 30°,45° and 60° were 0.457 5,0.272 8,and 0.255 6,respectively.After optimization,the CV for the circular pattern(45°)decreased to 0.052 5,representing an 80.7％reduction compared to the pre-optimization value.Conclusions The moving patterns significantly affect the uniformity of dip-coating thickness distributions.The horizontal pattern demonstrates the best uniformity,while the vertical pattern shows the poorest uniformity.The CV for the circular pattern decreases as the angle increases,with its uniformity between that of the vertical and horizontal patterns.Optimization of moving pattern parameters based on simulation results has improved the uniformity of thickness distributions.

Objective To investigate the impact of eccentric placement for various types of artificial aortic valves on downstream flow dynamics.Methods A physiological pulsatile circulation simulation system was employed and particle image velocimetry(PIV)was utilized to analyze the downstream flow field variations for bioprosthetic and mechanical valves under two placement conditions:centralized placement(0 mm)and eccentric placement(1 mm).Hemodynamic parameters such as velocity,vorticity,and viscous shear stress were assessed to evaluate the flow field characteristics.Results By analyzing the flow field variations at four characteristic time points,namely,early systole,acceleration phase,peak systole,and deceleration phase,a significant difference in flow field distribution between bioprosthetic and mechanical valves was observed.The bioprosthetic valve exhibited a centrally symmetric jet with a higher flow velocity,whereas the mechanical valve displayed a three-jet structure with a lower central flow velocity.Under eccentric placement,the blood flow in the aortic sinus region was sluggish,with a reduction in average velocity,hindering the formation and maintenance of vortices.During the peak systolic phase,the maximum viscous shear stresses in the sinus region for the bioprosthetic and mechanical valves were 0.45 and 0.67 Pa,respectively,approaching the threshold for endothelial cell damage.Conclusions Eccentric placement of both mechanical and bioprosthetic valves resulted in reduced sinus blood flow velocity and diminished viscous shear stress,creating favorable conditions for thrombus formation.In clinical practice,careful attention should be given to the placement of valve replacement to prevent eccentric placement.

Objective To explore the impact of different moving patterns during the dip-coating process on thickness distributions of polymer heart valves.Methods Based on the volume of fluid(VOF)multiphase flow model,the Eulerian wall-film(EWF)model,and dynamic mesh technology,the dip-coating manufacturing process of polymer heart valves were numerically simulated.The effects of vertical,horizontal,and circular moving patterns on flow characteristics of the surface impregnation liquid and liquid film distributions under self-rotation conditions of the models were mainly studied.Subsequently,seven identical test points were set on each valve leaflet to collect thickness data,and the coefficient of variation(CV)was calculated to evaluate the uniformity of the liquid film thickness.Given that the vertical and horizontal patterns had fewer moving planes,limiting the optimization space,the circular pattern(45°)with richer moving planes was selected as the basis for optimization,and comparative analysis of numerical simulation was conducted.Results In the vertical pattern,the peak CV was 0.461 3;in the horizontal pattern,the CV was 0.060 8;and in the circular pattern,the CV at 30°,45° and 60° were 0.457 5,0.272 8,and 0.255 6,respectively.After optimization,the CV for the circular pattern(45°)decreased to 0.052 5,representing an 80.7％reduction compared to the pre-optimization value.Conclusions The moving patterns significantly affect the uniformity of dip-coating thickness distributions.The horizontal pattern demonstrates the best uniformity,while the vertical pattern shows the poorest uniformity.The CV for the circular pattern decreases as the angle increases,with its uniformity between that of the vertical and horizontal patterns.Optimization of moving pattern parameters based on simulation results has improved the uniformity of thickness distributions.

Objective To investigate the impact of eccentric placement for various types of artificial aortic valves on downstream flow dynamics.Methods A physiological pulsatile circulation simulation system was employed and particle image velocimetry(PIV)was utilized to analyze the downstream flow field variations for bioprosthetic and mechanical valves under two placement conditions:centralized placement(0 mm)and eccentric placement(1 mm).Hemodynamic parameters such as velocity,vorticity,and viscous shear stress were assessed to evaluate the flow field characteristics.Results By analyzing the flow field variations at four characteristic time points,namely,early systole,acceleration phase,peak systole,and deceleration phase,a significant difference in flow field distribution between bioprosthetic and mechanical valves was observed.The bioprosthetic valve exhibited a centrally symmetric jet with a higher flow velocity,whereas the mechanical valve displayed a three-jet structure with a lower central flow velocity.Under eccentric placement,the blood flow in the aortic sinus region was sluggish,with a reduction in average velocity,hindering the formation and maintenance of vortices.During the peak systolic phase,the maximum viscous shear stresses in the sinus region for the bioprosthetic and mechanical valves were 0.45 and 0.67 Pa,respectively,approaching the threshold for endothelial cell damage.Conclusions Eccentric placement of both mechanical and bioprosthetic valves resulted in reduced sinus blood flow velocity and diminished viscous shear stress,creating favorable conditions for thrombus formation.In clinical practice,careful attention should be given to the placement of valve replacement to prevent eccentric placement.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.

Objective:To evaluate the application value of preconceptional laparoscopic cervical cerclage(LCC)in improving the pregnancy outcomes with cervical incompetence(CIC).Methods:Clinical data of 112 pa-tients with CIC who underwent preconceptional LCC in The First Affiliated Hospital of Zhengzhou University from July 1,2014 to May 31,2023 were retrospectively reviewed.The surgical indications of preconceptional LCC in-cluded:failed transvaginal cervical cerclage(TCC)(42 patients),history of cervical surgery+failed TCC(7 pa-tients),unsuitability for TCC(10 patients)and strong request from patients(53 patients).The surgical situation and pregnancy outcome of preconceptional LCC were analyzed,and the gestational age of delivery before and af-ter preconceptional LCC surgery and different surgical indications were compared in postoperative delivery pa-tients who underwent preconceptional LCC.Results:The median operation time of 112 patients was 65.5 min,the median intraoperative blood loss was 10.0 ml,and there were no intraoperative complications.The postopera-tive hospital stay was 2.9±0.6 d.108 cases were followed up after surgery,with 77 cases of pregnancy and de-livery after LCC.A total of 205 deliveries were made before surgery,and 81 deliveries were made after surgery.Successful postoperative deliveries(delivery after 28 weeks)were 78(96.3% ),with an average gestational age 37.4±1.7 weeks.The preterm birth rate was 16.7%,term birth rate was 83.3% .The delivery rate at≥28 weeks after preconceptional LCC was significantly higher than the previous delivery rate of pre pregnancy LCC(96.3% vs.10.7%,P<0.05),and the gestational age was significantly prolonged(36.4±5.5 weeks vs.19.8±7.5 weeks,P<0.05).The postoperative delivery gestational week of preconceptional LCC with different surgical indi-cations was significantly later than the previous delivery gestational week of pre pregnancy LCC(P<0.05),ex-cept for the indication of unsuitability for TCC(P>0.05).Conclusions:Preconceptional LCC surgery is highly safe and can effectively prolong the gestational age and improve pregnancy outcomes in patients with CIC.It can be an effective treatment method for patients with a history of TCC failure.