| Background Bileaflet mechanical heart valve has been widely used all over the world because of its hemodynamic properties and has achieved good therapeutic effects.Due to the lack of experimental research and clinical evidence of domestic bileaflet valve,the current domestic clinical application of the domestic bileaflet valve is still dominated by imported products.Therefore,the research on domestic bileaflet valve has positive social effects and economic benefits.Since the domestic CL-V all-carbon bileaflet mechanical heart valve(CL-V valve)was commercialized in 2015,there have been no reports was found yet in experimental research and clinical studies of this valve.Objectives In this paper,an in-vitro pulsatile flow experiment research were conducted to investigate the hydrodynamic performance of the CL-V valves and related influencing factors was discussed,clinical studies were undertaken to evaluate the safety and efficacy of CL-V valve,with the expectation of fulfilling the shortage of this domestic valve in both experimental research and clinical study.Methods PartⅠ:We designed the structure and proposal the pulsatile flow experimental system and the cardiac pulse duplicator(CPD)was developed by ourselves.The CPD was assessed according to the requirements of the current national standard GB12279-2008.The conditions and methods of in vitro pulsatile flow experiment were simulated and the hydrodynamic performance of the bileaflet valve was studied by using this CPD.Part Ⅱ: Under the constant simulated stroke volume and different simulated heart rates,the left ventricular pressure,aortic pressure and flow data of the CPD were recorded.The mean pressure gradient(MPG)and effective orifice area(EOA)of the CL-V valve were calculated by formulas.Using within-group variation test to analyze the effects of valve sizes and simulated heart rates on the hydrodynamic performance of the CL-V valve.The movement of the valve leaflets was observed directly by a high-speed camera.Part Ⅲ: We designed a retrospective cohort study that consecutively included patients who underwent isolated aortic valve replacement(AVR)and mitral valve replacement(MVR)in our hospital between December 2018 and December 2019.All Patients were divided into CL-V group and imported group after AVR or MVR,respectively.The primary outcome was a composite of perioperative results and endpoint events,echocardiographic evaluation and blood compatibility indexes during follow-up.A retrospective cohort study was conducted to compare the safety and efficacy of CL-V valve and imported valve.The safety were defined as the results of endpoint events and blood compatibility.The efficacy were defined as the results of perioperative and transthoracic echocardiography.Results PartⅠ:When the simulated heart rate was set at 60,80,100 and 120 bpm,the simulated cardiac output was 4.3,5.7,7.1 and 8.6 L/min,respectively.The mean left ventricular pressure ranged from 81.17 to 148.46 mm Hg,the mean aortic pressure ranged from 78.39 to 138.15 mm Hg.All of the tested valves opened and closed normally and the valves did not slip from the experimental device.No structural damage to the valves or experimental device was found.The experimental procedure yielded physiologically pulsatile waveforms.The entire pulsatile flow experimental results could meet the requirements of the national standard GB12279-2008.Part Ⅱ: The experiment showed that the CL-V valves worked normally and well during the continuous simulated cardiac cycle.When the experiment set a simulated strake volume was 70 ml constantly and heart rate range from 60 to 120 bpm,the MPG values of the 21 mm,23mm,25 mm and 27 mm valves were 7.94~18.21 mm Hg,8.58~16.50 mm Hg,6.73~16.39 mm Hg,7.37~15.94 mm Hg,respectively.EOA values of four type valves were 0.71~0.97cm~2,0.75~0.99cm~2,0.88~1.00cm~2 and 0.92~1.02cm~2,respectively.Within-group variation test showed that both MPG and EOA were affected by heart rate and valve size.MPG of 21 mm,23mm,and 25 mm valve was significantly greater than that of 27 mm valve at 60 and 80 bpm,respectively(P<0.001);MPG of four type valves was not significantly different at 80 and 100 bpm,respectively(P>0.05);MPG of 25 and 27 mm valves was significantly greater at 100 and 120 bpm than that of 21 and 23 mm valves,respectively(P>0.05).EOA were not significantly different in both 25 mm and 27 mm valves at 60 and 120 bpm(P>0.05);EOA of 21 mm and 23 mm valves was significantly different at 60 to 80 bpm compared with 100 to 120 bpm(P<0.05).Part Ⅲ: From December 2018 to December 2019,a total of 282 patients were consecutively enrolled in the study.The follow-up time was 1m~3y(median 6m).AVR was performed in 153 patients(CL-V group n=79,imported group n=74)and MVR was performed in 129 patients(CL-V group n=100,imported group n=29).179 CL-V valves and 103 imported valves were implanted in all patients.There was no significant differences between the groups in baseline characteristics(P>0.05).In AVR patients,there was a significant difference in perioperative results of preoperative aortic annulus size,aortic valve pressure difference,extracorporeal circulation time,blocking time,operation time and ICU time(P<0.05),respectively.In MVR patients,there was no significant difference between groups in perioperative results(P>0.05).During follow-up,16 and 23 patients had endpoint events in groups after AVR,26 and 6 patients in groups after MVR,respectively.Kaplan-Meier and Log-rank test showed there was no significant difference between groups in the endpoint events after AVR(P=0.13)and MVR(P=0.49),respectively.The evaluation of transthoracic echocardiography in 174 patients at the final follow-up showed that no significant difference between 23mm(n=11,n=7)and 25mm(n=61,n=13)valves in aortic position,respectively(P>0.05).There was no significant difference between 25mm(n=6,n=4),27mm(n=33,n=7),and 29mm(n=27,n=5)valves in mitral position,respectively(P>0.05).The blood compatibility indexes of 38 patients in two groups(CL-V valve n=18,imported valve n=20)were tested periodically,the results were in the normal range and showed no significant difference between groups,respectively(P>0.05).Conclusions PartⅠ:This in-vitro pulsatile flow experimental system could meet the requirements of the national standard GB12279-2008.It is an in-vitro pulsatile flow experimental method that can simulate physiological conditions to complete the study of hydrodynamic performance of prosthetic heart valves.Part Ⅱ: This in-vitro pulsatile flow experiment demonstrated the stable performance of the CL-V valve,both heart rate and valve size were found to affect the hydrodynamic performance of the CL-V valves under simulating strake volume was fixed.When the heart rate was constant,the hydrodynamic performance of the larger size was relatively better than smaller size,while the effect of heart rate variation on the hydrodynamic performance of smaller size was relatively more dramatic than that of larger size.Part Ⅲ: The results of the clinical study confirmed that the outcome of CL-V valve in this group had clinical benefits during perioperative and follow-up periods,the safety and efficacy were similar with respect to imported valves which has reference value for clinical research and application of CL-V valve in the further. |
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