de Waal Koert, Crendal Edward, Boyle Andrew
John Hunter Children's Hospital Department of Neonatology and University of Newcastle, Newcastle, New South Wales, Australia.
John Hunter Hospital Department of Cardiology and University of Newcastle, Newcastle, New South Wales, Australia.
Echocardiography. 2019 Jul;36(7):1364-1371. doi: 10.1111/echo.14391. Epub 2019 Jun 6.
A vortex is a rotational fluid structure formed by shearing of fluid layers. It forms during diastole in the left ventricle (LV) and helps redirect flow to the LV outflow tract for ejection, optimizing energy conservation. The aim of this study was to demonstrate the feasibility of detecting and analyzing LV vortices using a new ultrasound technique known as blood speckle imaging (BSI).
Conventional and BSI parameters were acquired in preterm infants referred for echocardiography. BSI feasibility and reliability were explored using highest frequency settings and optimized Nyquist limits. Vortex area was determined by tracing the outer vortex ring at maximum area. Peak vortex formation time (PVFT) was determined at time of maximum vortex area relative to the R-wave, and vortex duration from frame-by-frame analysis of first appearance to vortex degradation.
Left ventricle vortices were detected in 49 of the 50 preterm infants (weight 500-2020 g) with excellent intra- and inter-observer reliability. Mean vortex area indexed to LV area was 0.19 (0.08). Peak vortex formation time was at 87 (7)% of the cardiac cycle, and vortex duration lasted 13 (4)% of the cardiac cycle. Vortex area correlated positively with LV length, end-diastolic dimension, end-diastolic volume, mitral annular (R +0.42, +0.50, +0.47, +0.50, all P < 0.01), and transmitral Vti (R +0.37, P < 0.01). PVFT correlated negatively with E, EA, and Ee' (R -0.42, -0.47, -0.47, all P < 0.01).
Left ventricle vortex formation can be analyzed with two-dimensional BSI and has the potential to complement existing parameters of cardiac health.
涡流是由流体层剪切形成的旋转流体结构。它在左心室舒张期形成，有助于将血流重新导向左心室流出道以便射血，从而优化能量守恒。本研究的目的是证明使用一种称为血流散斑成像（BSI）的新型超声技术检测和分析左心室涡流的可行性。
对因超声心动图检查而转诊的早产儿获取常规参数和BSI参数。使用最高频率设置和优化的奈奎斯特极限来探索BSI的可行性和可靠性。通过在最大面积时追踪外涡流环来确定涡流面积。相对于R波，在最大涡流面积时确定峰值涡流形成时间（PVFT），并通过逐帧分析从首次出现到涡流退化来确定涡流持续时间。
在50例早产儿（体重500 - 2020 g）中的49例检测到左心室涡流，观察者内和观察者间的可靠性极佳。以左心室面积为指标的平均涡流面积为0.19（0.08）。峰值涡流形成时间在心动周期的87（7）%，涡流持续时间持续心动周期的13（4）%。涡流面积与左心室长度、舒张末期内径、舒张末期容积、二尖瓣环（R +0.42，+0.50，+0.47，+0.50，均P < 0.01）以及二尖瓣Vti（R +0.37，P < 0.01）呈正相关。PVFT与E、EA和Ee'呈负相关（R -0.42，-0.47，-0.47，均P < 0.01）。
左心室涡流形成可用二维BSI进行分析，并且有可能补充现有的心脏健康参数。
