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Published on: July 19, 2016
Coronary flow disturbance assessed by vorticity as a cause of functionally significant stenosis
Nobuo Tomizawa1, Yui Nozaki2, Shinichiro Fujimoto2
1Department of Radiology, Juntendo University Graduate School of Medicine, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. tomizawa-tky@umin.ac.jp.
Insights
Vorticity, a measure of flow disturbance, is significantly higher in functionally significant coronary stenosis. This finding indicates vorticity can help identify significant stenosis beyond geometric measurements.
Area of Science:
- Cardiovascular medicine
- Biomedical engineering
- Fluid dynamics
Background:
- Coronary stenosis can cause significant flow disturbances.
- Computational fluid dynamics (CFD) offers a method to quantify these disturbances through vorticity.
- Assessing the functional significance of stenosis is crucial for patient management.
Purpose of the Study:
- To investigate if vorticity, calculated via CFD, can identify functionally significant coronary stenosis.
- To determine the relationship between vorticity and invasive fractional flow reserve (FFR).
Main Methods:
- Retrospective analysis of 113 patients with intermediate coronary stenosis.
- Vorticity calculated using a mesh-free CFD method from coronary CT angiography.
- Comparison of vorticity with invasive FFR, minimum lumen area (MLA), and diameter stenosis (DS).
Main Results:
- Vorticity was significantly higher in vessels with functionally significant stenosis (FFR ≤ 0.80).
- A significant negative correlation was found between vorticity and invasive FFR (R² = 0.31).
- Vorticity independently predicted functional significance and improved stenosis detection when combined with MLA and DS.
Conclusions:
- Vorticity is a valuable parameter for assessing flow disturbance in coronary stenosis.
- Higher vorticity correlates with functionally significant stenosis, independent of geometric factors.
- Vorticity provides additive value to traditional geometric measures for detecting significant coronary artery disease.
Objectives:
Vorticity calculated using computational fluid dynamics (CFD) could assess the flow disturbance generated by coronary stenosis. The purpose of this study was to investigate whether vorticity would be an underlying cause of functionally significant stenosis assessed by invasive fractional flow reserve (FFR).
Methods:
This retrospective study included 113 patients who underwent coronary CT angiography showing intermediate stenosis and subsequent invasive FFR between December 2015 and March 2020. Vorticity at the stenosis site was calculated using a mesh-free CFD method. We also evaluated the minimum lumen area (MLA) and diameter stenosis (DS) of the lesion. Invasive FFR of ≤ 0.80 was considered functionally significant. Data were compared using Student's t-test and logistic regression analysis was performed.
Results:
Of the evaluated 144 vessels, 53 vessels (37%) showed FFR ≤ 0.80. Vorticity of significant stenosis was significantly higher than non-significant stenosis (569 ± 78 vs. 328 ± 34 s-1, p < 0.001). A significant negative relationship was present between vorticity and invasive FFR (R2 = 0.31, p < 0.001). Multivariate logistic regression analysis including MLA and DS showed that vorticity (per 100 s-1, odds ratio: 1.36, 95% confidence interval: 1.21-1.57, p < 0.001) was a statistically significant factor to detect functional significance. The area under the receiver operating characteristic curve statistically significantly increased when vorticity was combined with DS and MLA (0.76 vs. 0.87, p = 0.001).
Conclusions:
Vorticity had a statistically significant negative relationship with invasive FFR independent of geometric stenosis.
Key Points:
• Flow disturbance caused by coronary stenosis could be evaluated by calculating vorticity which is defined as the norm of the rotation of the velocity vector. • Vorticity was statistically significantly higher in stenosis with functional significance than stenosis without. • Vorticity has an additive value to detect functionally significant stenosis over geometrical stenosis.
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