Quantitative Research In Vivo On Hemodynamics Downstream Of Prosthetic Mitral Vavle With Preservation Of Subvalvular Apparatus

Part â… :Methodological study of measuring quantitatively Turbulent Sheat Stress downsstream of prosthetic mitral vavle with different preservation of subvalvular apparatus in swine using Doppler echocardiography1. Model creation of mitra vavle replacement (MVR)with preservingthe subvalvular apparatus with different methods in swineObjective:The purpose of this study was to discuss the key factors of established animal model of MVR with preserving the subvavular apparatus in swine and to assess the feasibility and value of the animal model.Methods:12closed clony domestic swines performed mitral valve replacement through the left atrial appendage route under the cardio pulmonary bypass (CPB) and general anesthesia.12swines were divided into three groups randomly. Group A: Both anterior and posterior leaflet and chordae tendineae were excised; Group B: Only anterior leaflet was excised, and posterior subvalvular apparatus was retained; Group C:Total subvalvular apparatus was retained. Then prosthetic valve was implanted.Result:A totally10animal models were made successfully. The creation ratio was83.3%in this experimental study. One of causes of failure is that clamp time is too long. The other is hypothermia that causes ventricular fibrillation. Other models were used for observation successfully.Conclusion:The method of creating MVR model with preserving subvalvular apparatus is simple, effective and with a satisfied success ratio. This model can be used for observation easily. 2. Methodological study of measuring quantitatively Turbulent Shear Stress downsstream of prosthetic mitral vavle in swine using Doppler echocardiographyObjective:By comparing with the hot-film anemometry(HFA), to prove that the method of measuring quantitatively Turbulent Sheat Stress(TSS) by Doppler echocardiography combined with computerized image analysis was accurative and feasible.Methods:In established swine models, using HFA and Doppler echocardiography combined with computerized image analysis respectively to measure TSS in the downstream of prosthetic mitral valve at the same time and the same location, compare the results to evaluate the correlation and agreement of two methods.Result:TSS measured by doppler echocardiography combined with computerized image analysis had good correlation with those measured with HFA(r=0.93, P<0.05). Bland-Altman analysis revealed good agreement in TSS between two methods.Conclusion:Doppler echocardiography combined with computerized image analysis was safe, non-invasive, accurate and feasible, could be used to research hemodynamic performance in the downstream of prosthetic mitral valve. Part â…¡:Clinical Study on hemodynamics in the downstream of different prosthetic mitral valve with different preservation of subvalvular apparatus.3. Clinical Study on hemodynamics in the downstream of prosthetic mitral valve with different preservation of subvalvular apparatus.Objective:By comparing hemodynamics in the downstream of prosthetic mitral valve with different preservation of subvavular apparatus, to study the effect that the preservation of subvalvular apparatus interfere with the hemodynamic actions downstream of prosthetic mitral valve during MVR.Methods:Patients were divided into different groups according to different preservation of subvavular apparatus. PGmean, Qmv, LVEF, LVESD, Vmax,â–³Vmax were measued by Doppler echocardiography, TSS and Irel was computed by Doppler echocardiography combining with the analysis of image by computer.Result:1. Preservation of subvalvular apparatus is to some extent beneficial to the left ventricular function of patients, especially for those with total preservation(P<0.05).2. Preservation of subvalvular apparatus to some extent result in an incremental disturbance of transvalvular flow, which causes that the flow field uniformity in the downstream of prosthetic mitral valve becomes worse and that TSS and Irel increase(P <0.05).Conclusion:1. Preservation of subvalvular apparatus is beneficial to the left ventricular function of patients.2. Preservation of subvalvular apparatus to some extent result in an incremental disturbance of transvalvular flow.3. MVR with preservation of posterior subvavular apparatus is more suitable to most patients. 4. Clinical Study on hemodynamics in the downstream of different prosthetic mitral valve with preservation of subvalvular apparatus.Objective:By comparing hemodynamics in the downstream of different prosthetic mitral valve with preservation of subvavular apparatus, to study the effect that different prosthetic mitral valve interfere with the hemodynamic actions downstream.Methods:Patients were divided into different groups according to different prosthetic mitral valve. PGmean, Qmv, LVEF, LVESD, Vmax,â–³Vmax were measued by Doppler echocardiography, TSS and Irei was computed by Doppler echocardiography combining with the analysis of image by computer.Result:1. Without preservation of subvalvular apparatus, there was no significant difference in PGmean, Qmv among groups (P>0.05).2. With preservation of posterior subvalvular apparatus, there was no significant difference between bileaflet group and bioprosthetic group(P>0.05), there was significant difference between tilting-disc group and other two group(P<0.05), tilting-disc group is inferior to other two group.3. With preservation of anterior and posterior subvalvular apparatus, there was significant difference among groups, bioprosthetic group is superior to bileaflet group, bileaflet group is superior to tilting-disc group.Conclusion:1. As to MVR with preservation of posterior subvalvular apparatus, bileaflet valve and bioprosthetic valve can be choosed according to the age and need of patients.2. As to the patient who have poor cardiac function and have to preserve simultaneously anterior and posterior subvalvular apparatus, if possible we suggest that bioprosthetic should be used so as to lessen the disadvantageous effect of subvavular apparatus on hemodynamics downstream of prostheses.