School of Biomedical Engineering & Imaging Sciences, King's College London, London, UK.
Cardiology Department, Guy's and St Thomas' NHS Foundation Trust, London, UK.
Cardiovasc Ultrasound. 2022 Jul 16;20(1):18. doi: 10.1186/s12947-022-00286-1.
Transvalvular pressure drops are assessed using Doppler echocardiography for the diagnosis of heart valve disease. However, this method is highly user-dependent and may overestimate transvalvular pressure drops by up to 54%. This work aimed to assess transvalvular pressure drops using velocity fields derived from blood speckle imaging (BSI), as a potential alternative to Doppler. METHODS: A silicone 3D-printed aortic valve model, segmented from a healthy CT scan, was placed within a silicone tube. A CardioFlow 5000MR flow pump was used to circulate blood mimicking fluid to create eight different stenotic conditions. Eight PendoTech pressure sensors were embedded along the tube wall to record ground-truth pressures (10 kHz). The simplified Bernoulli equation with measured probe angle correction was used to estimate pressure drop from maximum velocity values acquired across the valve using Doppler and BSI with a GE Vivid E95 ultrasound machine and 6S-D cardiac phased array transducer.
There were no significant differences between pressure drops estimated by Doppler, BSI and ground-truth at the lowest stenotic condition (10.4 ± 1.76, 10.3 ± 1.63 vs. 10.5 ± 1.00 mmHg, respectively; p > 0.05). Significant differences were observed between the pressure drops estimated by the three methods at the greatest stenotic condition (26.4 ± 1.52, 14.5 ± 2.14 vs. 20.9 ± 1.92 mmHg for Doppler, BSI and ground-truth, respectively; p < 0.05). Across all conditions, Doppler overestimated pressure drop (Bias = 3.92 mmHg), while BSI underestimated pressure drop (Bias = -3.31 mmHg).
BSI accurately estimated pressure drops only up to 10.5 mmHg in controlled phantom conditions of low stenotic burden. Doppler overestimated pressure drops of 20.9 mmHg. Although BSI offers a number of theoretical advantages to conventional Doppler echocardiography, further refinements and clinical studies are required with BSI before it can be used to improve transvalvular pressure drop estimation in the clinical evaluation of aortic stenosis.
使用多普勒超声心动图评估跨瓣压力降，用于诊断心脏瓣膜疾病。然而，这种方法高度依赖于使用者，并且可能高估跨瓣压力降多达 54%。本研究旨在使用血流斑点成像（BSI）衍生的速度场评估跨瓣压力降，作为多普勒的潜在替代方法。
将从健康 CT 扫描中分割的硅酮 3D 打印主动脉瓣模型放置在硅酮管内。使用 CardioFlow 5000MR 流量泵循环血液模拟液，以创建八种不同的狭窄条件。沿管壁嵌入八个 PendoTech 压力传感器，以记录地面真实压力（10 kHz）。使用简化的伯努利方程，结合测量的探头角度校正，从使用多普勒和 BSI 在 GE Vivid E95 超声机和 6S-D 心脏相控阵换能器上获取的跨瓣最大速度值估计压力降。
在最低狭窄条件下（分别为 10.4 ± 1.76、10.3 ± 1.63 和 10.5 ± 1.00 mmHg），由多普勒、BSI 和地面真实值估计的压力降之间没有显著差异（p > 0.05）。在最大狭窄条件下，三种方法估计的压力降之间存在显著差异（分别为 26.4 ± 1.52、14.5 ± 2.14 和 20.9 ± 1.92 mmHg，p < 0.05）。在所有条件下，多普勒都高估了压力降（偏差= 3.92 mmHg），而 BSI 则低估了压力降（偏差= -3.31 mmHg）。
BSI 在低狭窄负荷的受控幻影条件下仅能准确估计低至 10.5 mmHg 的压力降。多普勒高估了 20.9 mmHg 的压力降。虽然 BSI 相对于传统多普勒超声心动图具有许多理论优势，但在将 BSI 用于改善主动脉瓣狭窄的临床评估中的跨瓣压力降估计之前，还需要进行进一步的改进和临床研究。
