Grimes R Y, Pulido G A, Levine R A, Yoganathan A P
Cardiovascular Fluid Mechanics Laboratory, Schools of Mechanical and Chemical Engineering, Georgia Institute of Technology, Atlanta 30332-0363, USA.
J Biomech Eng. 1996 Nov;118(4):498-505. doi: 10.1115/1.2796036.
Mitral and tricuspid regurgitation create turbulent jets within the atria. Clinically, for the purpose of estimating regurgitant severity, jet size is assumed to be proportional to peak jet flow rate and regurgitant volume. Unfortunately, the relationship is more complex because the determinants of jet size include interactions between jet pulsatility, jet momentum, atrial width, and the velocity of ambient atrial counterflows. These effects on fluorescent jet penetration were measured using an in vitro simulation. Both steady and pulsatile jets were driven into an opposing counterflow velocity field peak jet length (Ljp) measurements made as a function of (1) peak orifice velocity (Ujp), (2) the time required for the jet to accelerate from zero to peak velocity and begin to decelerate (Tjp), (3) jet orifice diameter (Dj), (4) counterflow velocity (Uc), and (5) counterflow tube diameter (Dc). A compact mathematical description was developed using dimensional analysis. Results showed that peak jet length was a function of the counterflow tube diameter, the ratio of peak jet to counterflow momentum, (Mjp/Mc) = (U2jpD2j)/(U2cD2c), and a previously undescribed jet pulsatility parameter, the pulsatility index (PI), PI = D2c/(TjpUjpDj). For the same jet orifice flow conditions, jet penetration decreased as chamber diameter decreased, as the jet PI increased, and as the momentum ratio decreased. These interactions provide insight into why regurgitant jet size is not always a good estimate of regurgitant severity.
二尖瓣和三尖瓣反流会在心房内产生湍流。临床上，为了评估反流的严重程度，通常认为射流大小与射流峰值流速和反流容积成正比。然而，这种关系更为复杂，因为射流大小的决定因素包括射流搏动性、射流动量、心房宽度以及周围心房逆流速度之间的相互作用。使用体外模拟测量了这些因素对荧光射流穿透的影响。将稳定射流和搏动射流都引入到一个反向逆流速度场中，测量峰值射流长度（Ljp），该长度是以下因素的函数：（1）峰值孔口速度（Ujp）；（2）射流从零加速到峰值速度并开始减速所需的时间（Tjp）；（3）射流孔口直径（Dj）；（4）逆流速度（Uc）；（5）逆流管直径（Dc）。通过量纲分析得出了一个简洁的数学描述。结果表明，峰值射流长度是逆流管直径、峰值射流与逆流动量之比（Mjp/Mc）=（U2jpD2j）/（U2cD2c）以及一个先前未描述的射流搏动性参数——搏动指数（PI），PI = D2c/（TjpUjpDj）的函数。在相同的射流孔口流动条件下，随着腔室直径减小、射流PI增加以及动量比减小，射流穿透深度会降低。这些相互作用有助于解释为什么反流射流大小并不总是评估反流严重程度的良好指标。
