1
|
Diagnostic performance of corrected FFR CT metrics to predict hemodynamically significant coronary artery stenosis. Eur Radiol 2021; 31:9232-9239. [PMID: 34080038 DOI: 10.1007/s00330-021-08064-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/21/2021] [Accepted: 05/07/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVES To determine the diagnostic performance of the fractional flow reserve (FFR) derived from coronary computed tomography angiography (CCTA) (FFRCT) difference across the lesion (ΔFFRCT lesion) or the vessel (ΔFFRCT vessel) and the gradient of FFRCT for the identification of hemodynamically significant coronary stenosis. METHODS From June 2016 to December 2018, 73 patients suspected of having coronary artery disease who underwent CCTA followed invasive coronary angiography (ICA) within 1 month were retrospectively included. ΔFFRCT lesion, ΔFFRCT vessel, and FFRCT gradient were calculated. Performance characteristics of different corrected FFRCT metrics in detecting ischemic stenosis were analyzed. Impacts of coronary calcification and lesion length on the corrected FFRCT metrics were also analyzed. RESULTS The diagnostic sensitivities, specificities, and accuracies of 94.4%, 88.7%, and 91.0% with ΔFFRCT lesion, 57.1%, 72.3%, and 65.2% with ΔFFRCT vessel, and 50.0%, 85.1%, and 68.5% with FFRCT gradient, respectively, were detected. There was higher specificity, accuracy, and area under the curve (AUC) for ΔFFRCT lesion compared with CCTA (p < 0.05 for all). The specificity and AUC of FFRCT gradient and ΔFFRCT vessel were significantly higher than CCTA (p < 0.05 for all). Coronary calcification showed no impact on corrected FFRCT metrics. ΔFFRCT lesion for lesion length ratio (LLR) < 1/10 was significantly lower than that for LLR 1/10 to 3/10 and LLR > 3/10. CONCLUSIONS ΔFFRCT lesion was significantly correlated with the hemodynamically significant coronary artery stenosis. ΔFFRCT lesion had the potential to be immediately used in real-world practice to discriminate ischemic coronary artery stenosis. KEY POINTS • The difference of FFRCT across the lesion or the vessel and the gradient of FFRCT was related to the hemodynamically significant coronary artery stenosis. • The difference of FFRCT across the lesion showed the best diagnostic performance in detecting the hemodynamically significant coronary artery stenosis. • Coronary calcification showed no impact on corrected FFRCT metrics, while lesion length related to the difference of FFRCT across the lesion.
Collapse
|
2
|
Liu H, Ou S, Liu P, Xu Y, Gong Y, Xia L, Leng X, Leung TWH, Shi L, Zheng D. Effect of microcirculatory resistance on coronary blood flow and instantaneous wave-free ratio: A computational study. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 196:105632. [PMID: 32615491 DOI: 10.1016/j.cmpb.2020.105632] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVE The instantaneous wave-free ratio (iFR) has been proposed to estimate the hemodynamic severity of atherosclerotic stenosis in coronary arteries. The atherosclerotic stenosis in a proximal coronary artery could change its distal microcirculatory resistance (MR). However, there is a lack of investigation about the effect of MR variation on the blood flow and iFR of stenotic coronary arteries. We aim to investigate the changes of blood flow and iFR caused by distal MR variation. METHODS Four three-dimensional models of coronary arteries were reconstructed from the computed tomography images of two normal cases and two cases with 74.9% and 96.4% (in area) stenoses in a large branch of left anterior descending artery (LAD). Computational fluid dynamics simulation was performed on each model under 6 MR situations: hyperemia as the reference situation, resting when MR was multiplied by 8/3 in all outlet branches, h-one-1.5 and h-one-2 when MR was multiplied by 1.5 and 2.0 in one branch (the stenotic, or the corresponding branch in normal case) of LAD, h-branches-1.5 and h-branches-2 when MR was multiplied by 1.5 and 2.0 in the stenotic/corresponding and its cognate branches. Flow rate and iFR of each outlet branch were then calculated and compared between different MR situations to investigate the effect of MR variation on flow rate and iFR. RESULTS In the 74.9% stenosed and normal cases, referring to the hyperemia situation, the increase of MR in any branch significantly decreased its flow rate and increased its iFR, with limited effect on the flow rate (<3%) and iFR (<0.01) of other branches. However, in the 96.4% stenosed case, the doubled MR in the stenosed branch (h-one-2) significantly increased the flow rate (>10%) and iFR (>0.05) of its cognate branches. CONCLUSION The increase of MR in a normal or mildly stenosed branch of coronary artery decreases its blood flow and increases its iFR, with limited effect on other branches. Whereas, the increase of MR in a severely stenotic large branch could significantly increase the flow velocity and iFR of its cognate branches.
Collapse
Affiliation(s)
- Haipeng Liu
- Research Centre for Intelligent Healthcare, Faculty of Health and Life Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Shanxing Ou
- Department of Radiology, General Hospital of Southern Theater Command, PLA, Guangzhou, China
| | - Panli Liu
- Department of Radiology, Guangzhou First People's Hospital, Nansha Hospital, Guangzhou, China
| | - Yuhang Xu
- Research Centre for Intelligent Healthcare, Faculty of Health and Life Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Yinglan Gong
- Department of Biomedical Engineering, Zhejiang University, Hangzhou, China
| | - Ling Xia
- Department of Biomedical Engineering, Zhejiang University, Hangzhou, China
| | - Xinyi Leng
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China
| | - Thomas Wai Hong Leung
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China
| | - Lin Shi
- Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
| | - Dingchang Zheng
- Research Centre for Intelligent Healthcare, Faculty of Health and Life Sciences, Coventry University, Coventry CV1 5FB, UK.
| |
Collapse
|
3
|
GOVINDARAJU KALIMUTHU, VISWANATHAN GIRISHN, BADRUDDIN IRFANANJUM, WELDEMARIAM SIRAKAREGAWI, GEBREHIWOT WOLDUZINA, KAMANGAR SARFARAZ. THE MECHANICAL FACTORS INFLUENCING THE ASSESSMENT OF INTERMEDIATE STENOSIS SEVERITY EXPLAINED THROUGH FRACTIONAL FLOW RESERVE. J MECH MED BIOL 2017. [DOI: 10.1142/s0219519417300010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Assessment of intermediate coronary lesions with diameter stenosis of 40% to 70% severity is being a challenge for cardiologist to identify potentially ischemic stenosis for revascularization and nonculprit stenosis which can be deferred from stenting. An invasive coronary angiography and intravascular ultrasound provide anatomic information of stenosis severity whereas an invasive fractional flow reserve index (FFR) provides the functional significance of the stenosis severity. The measurement of functional significance of stenosis severity minimizes the procedural complications such as coronary dissection, in stent restenosis etc. rather than anatomical significance measure. The FFR cutoff value of [Formula: see text]0.8 is used to distinguish ischemic and nonischemic stenosis. The FFR is clinically well validated even though it is influenced by the mechanical factors such as hyperemic flow and guide wire insertion. In recent times, noninvasive coronary computed tomography (CCTA) modality has become popular in the diagnosis of coronary artery disease. The CCTA permits the assessment of cross-sectional parameters such as minimum lumen area and lumen diameter, lesion length and plaque morphology. However, the CCTA provides limited information on the functional significance of stenotic lesions as compared to FFR. The purpose of this review is to discuss the mechanical factors influencing the invasive FFR while assessing the functional significance of intermediate stenosis severity. In addition, the hidden mechanical factors influencing the noninvasive CCTA assessment of stenosis severity will be discussed from the critical information obtained from FFR which could be beneficial for the clinician particularly in the assessment of intermediate stenosis severity.
Collapse
Affiliation(s)
- KALIMUTHU GOVINDARAJU
- Ethiopian Institute of Technology, School of Mechanical and Industrial Engineering, Mekelle University, Mekelle, Ethiopia
| | | | | | - SIRAK AREGAWI WELDEMARIAM
- Ethiopian Institute of Technology, School of Mechanical and Industrial Engineering, Mekelle University, Mekelle, Ethiopia
| | - WOLDU ZINA GEBREHIWOT
- Ethiopian Institute of Technology, School of Mechanical and Industrial Engineering, Mekelle University, Mekelle, Ethiopia
| | - SARFARAZ KAMANGAR
- Department of Mechanical Engineering, University of Malaya, Malaysia
| |
Collapse
|
4
|
Kamangar S, Badruddin IA, Badarudin A, Nik-Ghazali N, Govindaraju K, Salman Ahmed NJ, Yunus Khan TM. Influence of stenosis on hemodynamic parameters in the realistic left coronary artery under hyperemic conditions. Comput Methods Biomech Biomed Engin 2016; 20:365-372. [DOI: 10.1080/10255842.2016.1233402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sarfaraz Kamangar
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Irfan Anjum Badruddin
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - A. Badarudin
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - N. Nik-Ghazali
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Kalimuthu Govindaraju
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - N. J. Salman Ahmed
- Center for Energy Sciences, Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - T. M. Yunus Khan
- Department of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603, Malaysia
| |
Collapse
|
5
|
Govindaraju K, Viswanathan GN, Badruddin IA, Kamangar S, Salman Ahmed NJ, Al-Rashed AAAA. The influence of artery wall curvature on the anatomical assessment of stenosis severity derived from fractional flow reserve: a computational fluid dynamics study. Comput Methods Biomech Biomed Engin 2016; 19:1541-9. [PMID: 27052093 DOI: 10.1080/10255842.2016.1170119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment.
Collapse
Affiliation(s)
- Kalimuthu Govindaraju
- a Centre for Engineering Programs , HELP College of Arts and Technology , Kuala Lumpur , Malaysia
| | - Girish N Viswanathan
- b Cardiology department , Derriford Hospital , Plymouth , UK.,c Institute of Cellular Medicine , Newcastle University , Newcastle upon Tyne , UK
| | - Irfan Anjum Badruddin
- d Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - Sarfaraz Kamangar
- d Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - N J Salman Ahmed
- e Center for Energy Sciences, Department of Mechanical Engineering , University of Malaya , Kuala Lumpur , Malaysia
| | - Abdullah A A A Al-Rashed
- f Department of Automotive and Marine Engineering Technology , College of Technological Studies, The Public Authority for Applied Education and Training , Kuwait city , Kuwait
| |
Collapse
|
6
|
Rajabi-Jagahrgh E, Banerjee RK. Functional diagnostic parameters for arteriovenous fistula. Artif Organs 2015; 39:492-501. [PMID: 25865141 DOI: 10.1111/aor.12410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The inability to detect the arteriovenous fistula (AVF) dysfunction in a timely manner under the current surveillance programs, which are based on either diameter (d), flow rate (Q), or pressure (p) measurements, is one of the major challenges of dialysis treatment. Thus, our aim is to introduce new functional diagnostic parameters that can better predict AVF functionality status. Six AVFs were created between the femoral arteries and veins of three pigs, each pig having two AVFs on either limb. Flow fields and pressure drop (Δp) in AVFs were obtained via numerical analysis utilizing the CT scan and Doppler ultrasound data at 2D (D: days), 7D, and 28D postsurgery. The dataset included 16 (two pigs [four AVFs] for three time points, and one pig [two AVFs] for two time points) repeated measurements over time, and the statistical analysis was done using a mixed model. To evaluate the nature of pressure drop-flow relationships in AVFs, the Δp was correlated with the average velocity at proximal artery (v) and also the corresponding scaled velocity (v*) by the curvature ratio of anastomotic segment. Based on these relationships, two new functional diagnostic parameters, including the nonlinear pressure drop coefficient (Cp ; pressure drop divided by dynamic pressure at proximal artery) and the linear resistance index (R; pressure drop divided by velocity at proximal artery), were introduced. The diagnostic parameters that were calculated based on scaled velocity are represented as R* and Cp *. A marginal (P = 0.1) increase in d from 2D (5.4 ± 0.7 mm) to 7D (6.8 ± 0.7 mm), along with a significant increase in Q (2D: 967 ± 273 mL/min; 7D: 1943 ± 273 mL/min), was accompanied by an almost unchanged Δp over this time period (2D: 16.42 ± 4.6 mm Hg; 7D: 16.40 ± 4.6 mm Hg). However, the insignificant increase in d and Q from 7D to 28D (d = 7.8 ± 0.8 mm; Q = 2181 ± 378 mL/min) was accompanied by the elevation in Δp (24.6 ± 6.5 mm Hg). The functional diagnostic parameters, R and Cp , decreased from 2D (R = 22.4 ± 2.8 mm Hg/m/s; Cp = 12.0 ± 2.6) to 7D (R = 20.8 ± 2.8 mm Hg/m/s; Cp = 8.1 ± 2.6), and then increased from 7D to 28D (R = 35.5 ± 5.7 mm Hg/m/s; Cp = 17.5 ± 3.6) with a marginal significance. However, when the scaled velocity was used to calculate R* and Cp *, the increase in diagnostic parameters from 7D to 28D achieved statistical significance (P < 0.05). In summary, although the differences in the hemodynamic parameters (d, Q, and Δp) from 7D to 28D were insignificant, changes in their combined effects in the form of diagnostic parameters were significant. Therefore, the functional diagnostic parameters are capable of better distinguishing changes in the hemodynamic variations, and thus, could be promising endpoints to diagnose the functionality of AVFs over time.
Collapse
Affiliation(s)
- Ehsan Rajabi-Jagahrgh
- Mechanical Engineering Program, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Rupak K Banerjee
- Mechanical Engineering Program, Department of Mechanical and Materials Engineering, University of Cincinnati, Cincinnati, OH, USA.,Biomedical Engineering Program, Department of Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA.,Cincinnati Veterans Administration Medical Center, Cincinnati, OH, USA
| |
Collapse
|
7
|
Rajabi-Jaghargh E, Banerjee RK. Combined functional and anatomical diagnostic endpoints for assessing arteriovenous fistula dysfunction. World J Nephrol 2015; 4:6-18. [PMID: 25664243 PMCID: PMC4317629 DOI: 10.5527/wjn.v4.i1.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 08/26/2014] [Accepted: 11/19/2014] [Indexed: 02/06/2023] Open
Abstract
Failure of arteriovenous fistulas (AVF) to mature and thrombosis in matured fistulas have been the major causes of morbidity and mortality in hemodialysis patients. Stenosis, which occurs due to adverse remodeling in AVFs, is one of the major underlying factors under both scenarios. Early diagnosis of a stenosis in an AVF can provide an opportunity to intervene in a timely manner for either assisting the maturation process or avoiding the thrombosis. The goal of surveillance strategies was to supplement the clinical evaluation (i.e., physical examination) of the AVF for better and earlier diagnosis of a developing stenosis. Surveillance strategies were mainly based on measurement of functional hemodynamic endpoints, including blood flow (Qa) to the vascular access and venous access pressure (VAP). As the changes in arterial pressure (MAP) affects the level of VAP, the ratio of VAP to MAP (VAPR = VAP/MAP) was used for diagnosis. A Qa < 400-500 mL/min or a VAPR > 0.55 is considered sign of significant stenosis, which requires immediate intervention. However, due to the complex nature of AVFs, the surveillance strategies have failed to consistently detect stenosis under different scenarios. VAPR has been primarily developed to detect outflow stenosis in arteriovenous grafts, and it hasn’t been successful in accurate diagnosis of outflow lesions in AVFs. Similarly, AVFs can maintain relatively high blood flow despite the presence of a significant outflow stenosis and thus, Qa has been found to be a better predictor of only inflow lesions. Similar shortcomings have been reported in the detection of functional severity of coronary stenosis using diagnostic endpoints that were based on either flow or pressure. This limitation has been associated with the fact that both pressure and flow change in the presence of a stenosis and thus, hemodynamic diagnostic endpoints that employ only one of these parameters are inherently prone to inaccuracies. Recent attempts have resulted in development of new diagnostic endpoints that can combine the effects of pressure and flow. These new hemodynamic diagnostic endpoints have shown to be better predictors of functional severity of lesions as compared to either flow or pressure based counterparts. In this review article, we discussed the advantages and limitations of current functional and anatomical diagnostic endpoints in AVFs.
Collapse
|
8
|
Numerical investigation of the effect of stenosis geometry on the coronary diagnostic parameters. ScientificWorldJournal 2014; 2014:354946. [PMID: 25258722 PMCID: PMC4167444 DOI: 10.1155/2014/354946] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/20/2014] [Indexed: 01/07/2023] Open
Abstract
The present study deals with the functional severity of a coronary artery stenosis assessed by the fractional flow reserve (FFR). The effects of different geometrical shapes of lesion on the diagnostic parameters are unknown. In this study, 3D computational simulation of blood flow in three different geometrical shapes of stenosis (triangular, elliptical, and trapezium) is considered in steady and transient conditions for 70% (moderate), 80% (intermediate), and 90% (severe) area stenosis (AS). For a given percentage AS, the variation of diagnostic parameters which are derived from pressure drop across the stenosis was found in three different geometrical shapes of stenosis and it was observed that FFR is higher in triangular shape and lower in trapezium shape. The pressure drop coefficient (CDP) was higher in trapezium shape and lower in triangular model whereas the LFC shows opposite trend. From the clinical perspective, the relationship between percentage AS and FFR is linear and inversely related in all the three models. A cut-off value of 0.75 for FFR was observed at 76.5% AS in trapezium model, 79.5% in elliptical model, and 82.7% AS for the triangular shaped model. The misinterpretation of the functional severity of the stenosis is in the region of 76.5%-82.7 % AS from different shapes of stenosis models.
Collapse
|
9
|
Govindaraju K, Kamangar S, Badruddin IA, Viswanathan GN, Badarudin A, Salman Ahmed N. Effect of porous media of the stenosed artery wall to the coronary physiological diagnostic parameter: A computational fluid dynamic analysis. Atherosclerosis 2014; 233:630-635. [DOI: 10.1016/j.atherosclerosis.2014.01.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/05/2014] [Accepted: 01/20/2014] [Indexed: 11/28/2022]
|
10
|
Dong J, Inthavong K, Tu J. Image-based computational hemodynamics evaluation of atherosclerotic carotid bifurcation models. Comput Biol Med 2013; 43:1353-62. [DOI: 10.1016/j.compbiomed.2013.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/14/2013] [Accepted: 06/19/2013] [Indexed: 11/15/2022]
|
11
|
Haemodynamic analysis of the effect of different types of plaques in the left coronary artery. Comput Med Imaging Graph 2013; 37:197-206. [DOI: 10.1016/j.compmedimag.2013.02.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 01/08/2013] [Accepted: 02/27/2013] [Indexed: 11/18/2022]
|
12
|
Govindaraju K, Badruddin IA, Viswanathan GN, Ramesh SV, Badarudin A. Evaluation of functional severity of coronary artery disease and fluid dynamics' influence on hemodynamic parameters: A review. Phys Med 2012; 29:225-32. [PMID: 22704601 DOI: 10.1016/j.ejmp.2012.03.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 03/19/2012] [Accepted: 03/28/2012] [Indexed: 11/29/2022] Open
Abstract
Coronary Artery Disease (CAD) is responsible for most of the deaths in patients with cardiovascular diseases. Diagnostic coronary angiography analysis offers an anatomical knowledge of the severity of the stenosis. The functional or physiological significance is more valuable than the anatomical significance of CAD. Clinicians assess the functional severity of the stenosis by resorting to an invasive measurement of the pressure drop and flow. Hemodynamic parameters, such as pressure wire assessment fractional flow reserve (FFR) or Doppler wire assessment coronary flow reserve (CFR) are well-proven techniques to evaluate the physiological significance of the coronary artery stenosis in the cardiac catheterization laboratory. Between the two techniques mentioned above, the FFR is seen as a very useful index. The presence of guide wire reduces the coronary flow which causes the underestimation of pressure drop across the stenosis which leads to dilemma for the clinicians in the assessment of moderate stenosis. In such condition, the fundamental fluid mechanics is useful in the development of new functional severity parameters such as pressure drop coefficient and lesion flow coefficient. Since the flow takes place in a narrowed artery, the blood behaves as a non-Newtonian fluid. Computational fluid dynamics (CFD) allows a complete coronary flow simulation to study the relationship between the pressure and flow. This paper aims at explaining (i) diagnostic modalities for the evaluation of the CAD and valuable insights regarding FFR in the evaluation of the functional severity of the CAD (ii) the role of fluid dynamics in measuring the severity of CAD.
Collapse
|