scholarly journals Numerical Investigation of the Effect of Stenosis Geometry on the Coronary Diagnostic Parameters

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Sarfaraz Kamangar ◽  
Govindaraju Kalimuthu ◽  
Irfan Anjum Badruddin ◽  
A. Badarudin ◽  
N. J. Salman Ahmed ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Computational Simulation ◽  
Fractional Flow ◽  
Diagnostic Parameters ◽  
Flow Reserve ◽  
Geometrical Shapes ◽  
Elliptical Model ◽  
Different Shapes ◽  
Triangular Model ◽  
The Relationship

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.

Influence of Variable Native Arterial Diameter and Vasculature Status on Coronary Diagnostic Parameters

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Ishan Goswami ◽  
Srikara V. Peelukhana ◽  
Marwan F. Al-Rjoub ◽  
Lloyd H. Back ◽  
Rupak K. Banerjee
Keyword(s):  
Pressure Drop ◽  
Clinical Decision Making ◽  
Dynamic Pressure ◽  
Clinical Intervention ◽  
Clinical Decision ◽  
Fractional Flow ◽  
Arterial Diameter ◽  
Diagnostic Parameters ◽  
Flow Reserve

In current practice, diagnostic parameters, such as fractional flow reserve (FFR) and coronary flow reserve (CFR), are used to determine the severity of a coronary artery stenosis. FFR is defined as the ratio of hyperemic pressures distal (p˜rh) and proximal (p˜ah) to a stenosis. CFR is the ratio of flow at hyperemic and basal condition. Another diagnostic parameter suggested by our group is the pressure drop coefficient (CDP). CDP is defined as the ratio of the pressure drop across the stenosis to the upstream dynamic pressure. These parameters are evaluated by invasively measuring flow (CFR), pressure (FFR), or both (CDP) in a diseased artery using guidewire tipped with a sensor. Pathologic state of artery is indicated by lower CFR (<2). Similarly, FFR lower than 0.75 leads to clinical intervention. Cutoff for CDP is under investigation. Diameter and vascular condition influence both flow and pressure drop, and thus, their effect on FFR and CDP was studied. In vitro experiment coupled with pressure-flow relationships from human clinical data was used to simulate pathophysiologic conditions in two representative arterial diameters, 2.5 mm (N1) and 3 mm (N2). With a 0.014 in. (0.35 mm) guidewire inserted, diagnostic parameters were evaluated for mild (∼64% area stenosis (AS)), intermediate (∼80% AS), and severe (∼90% AS) stenosis for both N1 and N2 arteries, and between two conditions, with and without myocardial infarction (MI). Arterial diameter did not influence FFR for clinically relevant cases of mild and intermediate stenosis (difference < 5%). Stenosis severity was underestimated due to higher FFR (mild: ∼9%, intermediate: ∼ 20%, severe: ∼ 30%) for MI condition because of lower pressure drops, and this may affect clinical decision making. CDP varied with diameter (mild: ∼20%, intermediate: ∼24%, severe: by 2.5 times), and vascular condition (mild: ∼35%, intermediate: ∼14%, severe: ∼ 9%). However, nonoverlapping range of CDP allowed better delineation of stenosis severities irrespective of diameter and vascular condition.

Influence of Heart Rate and Contractility on Coronary Diagnostic Parameters With Normal Microvasculature in Porcine Model

2010 ◽  
Author(s):  
Kranthi K. Kolli ◽  
Mohamed Effat ◽  
Tarek Helmy ◽  
Massoud Leesar ◽  
Arif Imran ◽  
...  
Keyword(s):  
Heart Rate ◽  
Pressure Drop ◽  
Guide Wire ◽  
Dynamic Pressure ◽  
Fractional Flow ◽  
Diagnostic Parameters ◽  
In Vivo Experiments ◽  
Flow Reserve ◽  
Yorkshire Pigs

Invasive guide-wire measurements are used to assess coronary lesion severity under clinical settings. The objective of the present research is to determine the influence of heart rate (HR) and contractility (CY) on fractional flow reserve (FFR; the ratio of distal pressure to proximal pressure at a stenotic section) and pressure drop coefficient (CDPe; the ratio of trans-stenotic pressure drop to distal dynamic pressure). In-vivo experiments were performed on eight Yorkshire pigs, to evaluate the diagnostic parameters for the conditions “CY<1100 mmHg/sec” and “CY>1100 mmHg/sec,” and for the conditions “HR<110 bpm” and “HR>110 bpm”. It was found that in the presence of normal microvasculature the measured coronary diagnostic parameters (FFR and CDPe) have a significant mean difference for variation in contractility (0.59±0.04 to 0.89±0.045 for FFR and 121.63±18 to 23.53±18 for CDPe). The variation in HR has no significant effect on FFR and CDPe (0.72±0.048 to 0.74±0.048 and 54±20 to 53±20 respectively).

The relationship between the basal coronary translesional pressure ratio and fractional flow reserve

2017 ◽  
Vol 90 (5) ◽  
pp. 745-753 ◽  
Author(s):  
William M. Wilson ◽  
Anoop S. V. Shah ◽  
Duncan Birse ◽  
Emma Harley ◽  
David B. Northridge ◽  
...  
Keyword(s):  
Fractional Flow Reserve ◽  
Pressure Ratio ◽  
Fractional Flow ◽  
Flow Reserve ◽  
The Relationship

Diagnostic Uncertainties During Assessment of Serial Coronary Stenoses: An In Vitro Study

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Gavin A. D’Souza ◽  
Srikara V. Peelukhana ◽  
Rupak K. Banerjee
Keyword(s):  
Pressure Drop ◽  
Dynamic Pressure ◽  
Clinical Intervention ◽  
In Vitro Study ◽  
Gray Zone ◽  
Diagnostic Parameter ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Stenosis Severity

Currently, the diagnosis of coronary stenosis is primarily based on the well-established functional diagnostic parameter, fractional flow reserve (FFR: ratio of pressures distal and proximal to a stenosis). The threshold of FFR has a “gray” zone of 0.75–0.80, below which further clinical intervention is recommended. An alternate diagnostic parameter, pressure drop coefficient (CDP: ratio of trans-stenotic pressure drop to the proximal dynamic pressure), developed based on fundamental fluid dynamics principles, has been suggested by our group. Additional serial stenosis, present downstream in a single vessel, reduces the hyperemic flow, Q˜h, and pressure drop, Δp˜, across an upstream stenosis. Such hemodynamic variations may alter the values of FFR and CDP of the upstream stenosis. Thus, in the presence of serial stenoses, there is a need to evaluate the possibility of misinterpretation of FFR and test the efficacy of CDP of individual stenoses. In-vitro experiments simulating physiologic conditions, along with human data, were used to evaluate nine combinations of serial stenoses. Different cases of upstream stenosis (mild: 64% area stenosis (AS) or 40% diameter stenosis (DS); intermediate: 80% AS or 55% DS; and severe: 90% AS or 68% DS) were tested under varying degrees of downstream stenosis (mild, intermediate, and severe). The pressure drop-flow rate characteristics of the serial stenoses combinations were evaluated for determining the effect of the downstream stenosis on the upstream stenosis. In general, Q˜h and Δp˜ across the upstream stenosis decreased when the downstream stenosis severity was increased. The FFR of the upstream mild, intermediate, and severe stenosis increased by a maximum of 3%, 13%, and 19%, respectively, when the downstream stenosis severity increased from mild to severe. The FFR of a stand-alone intermediate stenosis under a clinical setting is reported to be ∼0.72. In the presence of a downstream stenosis, the FFR values of the upstream intermediate stenosis were either within (0.77 for 80%–64% AS and 0.79 for 80%–80% AS) or above (0.88 for 80%–90% AS) the “gray” zone (0.75–0.80). This artificial increase in the FFR value within or above the “gray” zone for an upstream intermediate stenosis when in series with a clinically relevant downstream stenosis could lead to misinterpretation of functional stenosis severity. In contrast, a distinct range of CDP values was observed for each case of upstream stenosis (mild: 8–10; intermediate: 47–54; and severe: 130–155). The nonoverlapping range of CDP could better delineate the effect of the downstream stenosis from the upstream stenosis and allow for the accurate diagnosis of the functional severity of the upstream stenosis.

scholarly journals The relationship between coronary stenosis morphology and fractional flow reserve: a computational fluid dynamics modelling study

2021 ◽  
Author(s):  
Roberto T F Newcombe ◽  
Rebecca C Gosling ◽  
Vignesh Rammohan ◽  
Patricia V Lawford ◽  
D Rodney Hose ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Coronary Artery ◽  
Fractional Flow Reserve ◽  
Computational Modelling ◽  
Fractional Flow ◽  
Cfd Modelling ◽  
Flow Reserve ◽  
The Relationship ◽  
Lesion Severity

Abstract Background International guidelines mandate the use of fractional flow reserve (FFR) and/or non-hyperaemic pressure ratios to assess the physiological significance of moderate coronary artery lesions to guide revascularisation decisions. However, they remain underused such that visual estimation of lesion severity continues to be the predominant decision-making tool. It would be pragmatic to have an improved understanding of the relationship between lesion morphology and haemodynamics. Aims To compute virtual FFR (vFFR) in idealised coronary artery geometries with a variety of stenosis and vessel characteristics Methods Coronary artery geometries were modelled, based upon physiologically realistic branched arteries. Common stenosis characteristics were studied, including % narrowing, length, eccentricity, shape, number, position relative to branch, and distal (myocardial) resistance. Computational fluid dynamics (CFD) modelling was used to calculate vFFRs using the VIRTUheartTM system. Results Percentage lesion severity had the greatest effect upon FFR. Any ≥80% diameter stenosis in two views (i.e. concentric) was physiologically significant (FFR ≤ 0.80), irrespective of length, shape or vessel diameter. Almost all eccentric stenoses and all 50% concentric stenoses were physiologically non-significant, whilst 70% uniform concentric stenoses about 10mm long straddled the ischaemic threshold (FFR 0.80). A low microvascular resistance (MVR) reduced FFR on average by 0.05, and a high MVR increased it by 0.03. Conclusions Using computational modelling, we have produced an analysis of virtual FFR that relates stenosis characteristics to haemodynamic significance. The strongest predictor of a positive virtual FFR was a concentric, ≥80% diameter stenosis. The importance of MVR was quantified. Other lesion characteristics have a limited impact.

Functional and Anatomical Diagnosis of Coronary Artery Stenoses: A Retrospective Study in Humans

2012 ◽  
Author(s):  
Kranthi K. Kolli ◽  
Mohamed Effat ◽  
Imran Arif ◽  
Tarek Helmy ◽  
Massoud Leesar ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Dynamic Pressure ◽  
Microvascular Disease ◽  
Flow Coefficient ◽  
Fractional Flow ◽  
Throat Region ◽  
Flow Reserve ◽  
Stenosis Severity ◽  
Lesion Flow Coefficient ◽  
Hemodynamic Information

Fractional flow reserve (FFR: ratio of distal to proximal pressure of a stenotic section) is used to evaluate hemodynamic significance of epicardial stenosis. However, FFR and coronary flow reserve (CFR: ratio of hyperemic blood velocity to that of resting condition) are used in conjunction to evaluate combination of both epicardial and microvascular disease. It has been proposed that optimization of cutoff values for diagnostic parameters in determining stenosis severity depends on coupling functional (pressure and velocity) and anatomical data (% area stenosis). We hypothesize that, pressure drop coefficient (CDP: the ratio of trans-stenotic pressure drop to distal dynamic pressure) which has the functional information of pressure and velocity in its formulation correlates significantly with FFR and CFR, and lesion flow coefficient (LFC: ratio of % area stenoses to CDP at throat region) which combines both functional and anatomical (% area stenoses) information in its formulation correlates significantly with FFR, CFR and % area stenosis. We retrospectively analyzed the hemodynamic information from Meuwissen et al [3] to test this hypothesis. It was observed that, CDP, a functional index based on pressure drop and velocity, correlated linearly and significantly with FFR and CFR. And, LFC (combined functional and anatomic parameter) also correlated significantly with FFR, CFR (both hemodynamic endpoints) and % area stenosis (anatomic endpoint).

scholarly journals The Relationship between Fractional Flow Reserve, Platelet Reactivity and Platelet Leukocyte Complexes in Stable Coronary Artery Disease

PLoS ONE ◽  
2013 ◽  
Vol 8 (12) ◽  
pp. e83198 ◽  
Author(s):  
Jan-Willem E. M. Sels ◽  
Bert Rutten ◽  
Thijs C. van Holten ◽  
Marieke A. K. Hillaert ◽  
Johannes Waltenberger ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Coronary Artery ◽  
Fractional Flow Reserve ◽  
Platelet Reactivity ◽  
Stable Coronary Artery Disease ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Artery Disease ◽  
The Relationship

Fractional Flow Reserve Estimation in Coronary Arteries by Forward Geometrical Modeling

2013 ◽  
Author(s):  
Jelle T. C. Schrauwen ◽  
Jolanda J. Wentzel ◽  
Anton F. W. van der Steen ◽  
Frank J. H. Gijsen
Keyword(s):  
Clinical Practice ◽  
Pressure Drop ◽  
Coronary Arteries ◽  
Fractional Flow Reserve ◽  
Coronary Stenosis ◽  
Fractional Flow ◽  
Reserve Estimation ◽  
Important Indicator ◽  
Flow Reserve ◽  
Pressure Wire

Fractional Flow Reserve (FFR) is an important indicator for the hemodynamic significance of a coronary stenosis [1]. The FFR is defined as the pressure drop over the stenosis under hyperemia. The pressure drop, and thus the FFR, depends on both the geometry and flow. In clinical practice, the FFR is measured with a pressure wire under administration of adenosine and intervention is warranted if the FFR is below 0.8.

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