Evin Morgane, Magne Julien, Grieve Stuart M, Rieu Régis, Pibarot Philipe
Aix-Marseille Université, CNRS, Marseille, France.
Aix-Marseille Université, IFSTTAR, Marseille, France. Electronic correspondence:
J Heart Valve Dis. 2017 Nov;26(6):677-687.
Reference values of hemodynamic parameters for the assessment of prosthetic heart valves are necessary, and ideally need to be provided by entities independent of the valve manufacturers. Thus, the study aim was to provide, in vitro, normal reference values of the effective orifice area (EOA) for different models and sizes of mitral prosthetic valve, and to assess the determinants of EOA and mean transvalvular pressure gradient (mTPG).
Four models of mechanical prostheses were tested (one mono-leaflet, three bi-leaflet) and four models of bioprostheses (two bovine pericardial, two porcine) on a double-activation pulsed duplicator that was specifically designed and optimized for assessing the hemodynamic performance of mitral prosthetic valves. The hemodynamic conditions were standardized and included for bioprostheses: two mitral flow volumes, three mean aortic pressures, two heart rates, and three E/A ratios. The EOAs were measured with Doppler echocardiography, using the same method (continuity equation) as was used in the clinical setting. Overestimation in term of EOA was defined according to guidelines as >0.25 cm2.
EOA reference values were recorded. For mono-leaflet prostheses (Medtronic Hall 7700, size 25 to 31 mm) 2.29 and 3.49; for bi-leaflet prostheses (St. Jude Medical Master and Master HP, sizes 25 to 33 mm and On-X valve, sizes 27-29 mm) 1.34 and 4.74 cm2; for porcine bioprostheses (Medtronic Mosaic CINCH, sizes 25 to 31 mm and St. Jude Epic 100, sizes 25 to 33 mm) 1.35 and 3.56 cm2; for bovine pericardial bioprosthetic valves (Edwards Perimount 6900P and Magna Ease 7300, sizes 25 to 33 mm) 1.67 and 2.36 cm2. There were some discrepancies between the normal reference EOAs measured compared to those provided by the prosthesis manufacturers, or in published reports. The bioprosthetic EOAs were shown to be smaller than the manufacturers' values in 32% of valves (by an average of 0.57 ± 0.28 cm2) versus in 7% of valves when compared to values reported elsewhere (by an average of 0.43 ± 0.17 cm2). The relationship between EOA and internal orifice area (IOA) varied according to the type of prosthesis. The EOA was close to the IOA in mechanical valves (regression slopes 0.87-0.99) but was much smaller than the IOA in bioprosthetic valves (slopes 0.25-0.30). The EOA was influenced by prosthesis diameter, prosthesis stent diameter and height, while the mTPG was influenced by EOA and heart rate.
The present study has provided normal reference values of EOAs for several frequently used mitral prostheses. This information may be helpful for identifying and quantifying prosthetic valve dysfunction and prosthesis-patient mismatch.
评估人工心脏瓣膜时，血流动力学参数的参考值很有必要，理想情况下应由独立于瓣膜制造商的机构提供。因此，本研究的目的是在体外提供不同型号和尺寸的二尖瓣人工瓣膜有效瓣口面积（EOA）的正常参考值，并评估EOA和平均跨瓣压差（mTPG）的决定因素。
在专门设计和优化用于评估二尖瓣人工瓣膜血流动力学性能的双激活脉冲复制器上测试了四种机械瓣膜模型（一种单叶瓣，三种双叶瓣）和四种生物瓣膜模型（两种牛心包瓣，两种猪瓣）。血流动力学条件进行了标准化，对于生物瓣膜包括：两种二尖瓣血流量、三种平均主动脉压、两种心率和三种E/A比值。使用与临床环境相同的方法（连续方程）通过多普勒超声心动图测量EOA。根据指南，EOA高估定义为>0.25 cm²。
记录了EOA参考值。单叶瓣人工瓣膜（美敦力Hall 7700，尺寸25至31 mm）为2.29和3.49；双叶瓣人工瓣膜（圣犹达医疗Master和Master HP，尺寸25至33 mm以及On-X瓣膜，尺寸27 - 29 mm）为1.34和4.74 cm²；猪生物瓣膜（美敦力Mosaic CINCH，尺寸25至31 mm以及圣犹达Epic 100，尺寸25至33 mm）为1.35和3.56 cm²；牛心包生物瓣膜（爱德华Perimount 6900P和Magna Ease 7300，尺寸25至33 mm）为1.67和2.36 cm²。与人工瓣膜制造商提供的或已发表报告中的正常参考EOA相比，测量得到的结果存在一些差异。生物瓣膜的EOA在32%的瓣膜中显示小于制造商的值（平均小0.57±0.28 cm²），而与其他地方报告的值相比，在7%的瓣膜中小于该值（平均小0.43±0.17 cm²）。EOA与内瓣口面积（IOA）之间的关系因人工瓣膜类型而异。在机械瓣膜中EOA接近IOA（回归斜率0.87 - 0.99），但在生物瓣膜中EOA远小于IOA（斜率0.25 - 0.30）。EOA受人工瓣膜直径、人工瓣膜支架直径和高度影响，而mTPG受EOA和心率影响。
本研究提供了几种常用二尖瓣人工瓣膜的EOA正常参考值。这些信息可能有助于识别和量化人工瓣膜功能障碍及人工瓣膜 - 患者不匹配情况。
