FlowReserve Labs S.L., Santiago de Compostela, Spain; Galician Center for Mathematical Research and Technology (CITMAga), Santiago de Compostela, E15782, Spain; Group of Nonlinear Physics, Department of Physics, University of Santiago de Compostela, Santiago de Compostela, E15782, Spain.
FlowReserve Labs S.L., Santiago de Compostela, Spain.
Comput Methods Programs Biomed. 2024 Oct;255:108325. doi: 10.1016/j.cmpb.2024.108325. Epub 2024 Jul 14.
Fractional Flow Reserve (FFR) is generally considered the gold standard in hemodynamics to assess the impact of a stenosis on the blood flow. The standard procedure to measure involves the displacement of a pressure guide along the circulatory system until it is placed next to the lesion to be analyzed. The main objective of the present study is to analyze the influence of the pressure guide on the invasive FFR measurements and its implications in clinical practice.
We studied the influence of pressure wires on the measurement of Fractional Flow Reserve (FFR) through a combination of Computational Fluid Dynamics (CFD) simulations using 45 clinical patient data with 58 lesions and ideal geometries. The analysis is conducted considering patients that were subjected to a computer tomography and also have direct measurements using a pressure guide. Influence of the stenosis severity, degree of occlusion and blood viscosity has also been studied.
The influence of pressure wires specifically affects severe stenosis with a lumen diameter reduction of 50 % or greater. This type of stenosis leads to reduced hyperemic flow and increased coronary pressure drop. Thus, we identified that the placement of wires during FFR measurements results in partial obstruction of the coronary artery lumen, leading to increased pressure drop and subsequent reduction in blood flow. The severity of low FFR values associated with severe stenosis may be prone to overestimation when compared to stenosis without severe narrowing. These results have practical implications, particularly in the interpretation of lesions falling within the "gray zone" (0,75-0,80).
The pressure wire's presence significantly alters the flow on severe lesions, which has an impact on the FFR calculation. In contrast, the impact of the pressure wire appears to be reduced when the FFR is larger than 0.8. The findings provide critical information for physicians, emphasizing the need for cautious interpretation of FFR values, particularly in severe stenosis. It also offers insights into improving the correlation between FFRct models and invasive measurements by incorporating the influence of pressure wires.
血流分数储备（FFR）通常被认为是评估狭窄对血流影响的血流动力学金标准。标准测量程序包括沿着循环系统移动压力导丝，直到将其放置在要分析的病变旁边。本研究的主要目的是分析压力导丝对侵入性 FFR 测量的影响及其在临床实践中的意义。
我们通过使用 45 名临床患者的 58 个病变和理想几何形状的 45 个临床患者数据的计算流体动力学（CFD）模拟组合，研究了压力导丝对血流分数储备（FFR）测量的影响。该分析考虑了接受计算机断层扫描（CT）检查且使用压力导丝进行直接测量的患者。还研究了狭窄严重程度、闭塞程度和血液粘度的影响。
压力导丝的影响主要影响狭窄程度为 50%或更大的严重狭窄。这种类型的狭窄会导致充血性血流减少和冠状动脉压力下降增加。因此，我们发现 FFR 测量过程中导丝的放置会导致冠状动脉管腔部分阻塞，导致压力下降增加，随后血流减少。与无严重狭窄相比，与严重狭窄相关的低 FFR 值可能容易高估。这些结果具有实际意义，特别是在解释处于“灰色区域”（0.75-0.80）的病变时。
压力导丝的存在显著改变了严重病变的血流，这对 FFR 计算有影响。相比之下，当 FFR 大于 0.8 时，压力导丝的影响似乎会降低。这些发现为医生提供了重要信息，强调了在严重狭窄时需要谨慎解释 FFR 值，同时还为通过纳入压力导丝的影响来提高 FFRct 模型与侵入性测量之间的相关性提供了思路。
