School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
FEops NV, Ghent, Belgium.
J Cardiovasc Magn Reson. 2023 Jan 30;25(1):5. doi: 10.1186/s12968-023-00914-3.
Decisions in the management of aortic stenosis are based on the peak pressure drop, captured by Doppler echocardiography, whereas gold standard catheterization measurements assess the net pressure drop but are limited by associated risks. The relationship between these two measurements, peak and net pressure drop, is dictated by the pressure recovery along the ascending aorta which is mainly caused by turbulence energy dissipation. Currently, pressure recovery is considered to occur within the first 40-50 mm distally from the aortic valve, albeit there is inconsistency across interventionist centers on where/how to position the catheter to capture the net pressure drop.
We developed a non-invasive method to assess the pressure recovery distance based on blood flow momentum via 4D Flow cardiovascular magnetic resonance (CMR). Multi-center acquisitions included physical flow phantoms with different stenotic valve configurations to validate this method, first against reference measurements and then against turbulent energy dissipation (respectively n = 8 and n = 28 acquisitions) and to investigate the relationship between peak and net pressure drops. Finally, we explored the potential errors of cardiac catheterisation pressure recordings as a result of neglecting the pressure recovery distance in a clinical bicuspid aortic valve (BAV) cohort of n = 32 patients.
In-vitro assessment of pressure recovery distance based on flow momentum achieved an average error of 1.8 ± 8.4 mm when compared to reference pressure sensors in the first phantom workbench. The momentum pressure recovery distance and the turbulent energy dissipation distance showed no statistical difference (mean difference of 2.8 ± 5.4 mm, R = 0.93) in the second phantom workbench. A linear correlation was observed between peak and net pressure drops, however, with strong dependences on the valvular morphology. Finally, in the BAV cohort the pressure recovery distance was 78.8 ± 34.3 mm from vena contracta, which is significantly longer than currently accepted in clinical practise (40-50 mm), and 37.5% of patients displayed a pressure recovery distance beyond the end of the ascending aorta.
The non-invasive assessment of the distance to pressure recovery is possible by tracking momentum via 4D Flow CMR. Recovery is not always complete at the ascending aorta, and catheterised recordings will overestimate the net pressure drop in those situations. There is a need to re-evaluate the methods that characterise the haemodynamic burden caused by aortic stenosis as currently clinically accepted pressure recovery distance is an underestimation.
主动脉瓣狭窄的管理决策基于多普勒超声心动图测量的峰值压力降，而金标准导管测量评估的是净压力降，但受到相关风险的限制。这两种测量方法（峰值压力降和净压力降）之间的关系取决于升主动脉内的压力恢复，而压力恢复主要是由湍流能量耗散引起的。目前，压力恢复被认为发生在距离主动脉瓣 40-50mm 处，但不同介入中心在如何定位导管以获取净压力降方面存在不一致。
我们开发了一种基于 4D Flow 心血管磁共振（CMR）血流动量的无创方法来评估压力恢复距离。多中心采集包括具有不同狭窄瓣膜结构的物理血流体模，以验证该方法，首先与参考测量值进行比较，然后与湍流能量耗散（分别为 n=8 和 n=28 次采集）进行比较，并研究峰值压力降和净压力降之间的关系。最后，我们探索了由于在临床二叶式主动脉瓣（BAV）患者队列中忽略压力恢复距离而导致的心脏导管压力记录的潜在误差，该队列包括 n=32 名患者。
基于流动动量的压力恢复距离的体外评估与第一个工作台上的参考压力传感器相比，平均误差为 1.8±8.4mm。在第二个工作台上，动量压力恢复距离和湍流能量耗散距离之间没有统计学差异（平均差异 2.8±5.4mm，R=0.93）。在 BAV 队列中，从狭窄口到压力恢复的距离为 78.8±34.3mm，明显长于目前临床实践中接受的距离（40-50mm），37.5%的患者的压力恢复距离超过升主动脉的末端。
通过 4D Flow CMR 追踪动量，可以对压力恢复距离进行无创评估。在某些情况下，压力恢复并不总是在升主动脉完全完成，导管记录的净压力降将会高估。需要重新评估用于描述主动脉瓣狭窄引起的血流动力学负担的方法，因为目前临床上接受的压力恢复距离是一种低估。
