Influence of Variable Native Arterial Diameter on Fractional Flow Reserve: An In-Vitro Study

2012 ◽  
Author(s):  
Ishan Goswami ◽  
Srikara V. Peelukhana ◽  
Marwan Al-Rjoub ◽  
Lloyd H. Back ◽  
Rupak K. Banerjee
Keyword(s):  
Fractional Flow Reserve ◽  
In Vitro Study ◽  
Fractional Flow ◽  
Arterial Diameter ◽  
Severe Stenosis ◽  
Throat Region ◽  
Flow Reserve ◽  
Significant Difference ◽  
Arterial Diameters

Fractional flow reserve (FFR), the ratio of the pressures distal (Pd) and proximal (Pa) to a stenosis, and coronary flow reserve (CFR), the ratio of flows at maximal vasodilation to the resting condition, are widely used for determining the functional severity of a coronary artery stenosis. However, the diameter of the native artery might influence the FFR values. Therefore, using an in-vitro experimental study, we tested the variation of FFR for two arterial diameters, 2.5 mm (N1) and 3 mm (N2). We hypothesize that FFR is not influenced by native arterial diameter. For both N1 and N2, vasodilation-distal perfusion pressure (CFR-Prh) curves were obtained using a 0.35 mm guidewire by simulating physiologic flows under different blockage conditions: mild (64% area stenosis (AS)), intermediate (80% AS) and severe (90% AS). The FFR values for the two arterial models differed insignificantly, within 3%, for mild and intermediate stenoses but differed appreciably for severe stenosis (∼25%). This significant difference in FFR values for severe stenosis can be attributed to relatively larger difference in guidewire obstruction effect at the stenotic throat region of the two native arterial models. These findings confirm that FFR will not differ for the clinically relevant cases of mild and intermediate stenosis for different arterial diameters.

scholarly journals Effect of Varying Hemodynamic and Vascular Conditions on Fractional Flow Reserve: An In Vitro Study

2016 ◽  
Vol 5 (7) ◽  
Author(s):  
Kranthi K. Kolli ◽  
James K. Min ◽  
Seongmin Ha ◽  
Hilary Soohoo ◽  
Guanglei Xiong
Keyword(s):  
Fractional Flow Reserve ◽  
In Vitro Study ◽  
Vitro Study ◽  
Fractional Flow ◽  
Flow Reserve

scholarly journals A validated predictive model of coronary fractional flow reserve

2011 ◽  
Vol 9 (71) ◽  
pp. 1325-1338 ◽  
Author(s):  
Yunlong Huo ◽  
Mark Svendsen ◽  
Jenny Susana Choy ◽  
Z.-D. Zhang ◽  
Ghassan S. Kassab
Keyword(s):  
Analytical Model ◽  
Fractional Flow Reserve ◽  
Coronary Stenosis ◽  
Coronary Flow ◽  
Energy Losses ◽  
Fractional Flow ◽  
Conservation Of Energy ◽  
Flow Reserve

Myocardial fractional flow reserve (FFR), an important index of coronary stenosis, is measured by a pressure sensor guidewire. The determination of FFR, only based on the dimensions (lumen diameters and length) of stenosis and hyperaemic coronary flow with no other ad hoc parameters, is currently not possible. We propose an analytical model derived from conservation of energy, which considers various energy losses along the length of a stenosis, i.e. convective and diffusive energy losses as well as energy loss due to sudden constriction and expansion in lumen area. In vitro (constrictions were created in isolated arteries using symmetric and asymmetric tubes as well as an inflatable occluder cuff) and in vivo (constrictions were induced in coronary arteries of eight swine by an occluder cuff) experiments were used to validate the proposed analytical model. The proposed model agreed well with the experimental measurements. A least-squares fit showed a linear relation as (Δ p or FFR) experiment = a (Δ p or FFR) theory + b , where a and b were 1.08 and −1.15 mmHg ( r 2 = 0.99) for in vitro Δ p , 0.96 and 1.79 mmHg ( r 2 = 0.75) for in vivo Δ p , and 0.85 and 0.1 ( r 2 = 0.7) for FFR. Flow pulsatility and stenosis shape (e.g. eccentricity, exit angle divergence, etc.) had a negligible effect on myocardial FFR, while the entrance effect in a coronary stenosis was found to contribute significantly to the pressure drop. We present a physics-based experimentally validated analytical model of coronary stenosis, which allows prediction of FFR based on stenosis dimensions and hyperaemic coronary flow with no empirical parameters.

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.

P5617Repeatability of instantaneous wave-free ratio in comparison with fractional flow reserve

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
T Horie ◽  
M Hoshino ◽  
H Hirano ◽  
Y Kanno ◽  
H Ohya ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Fractional Flow Reserve ◽  
Repeated Measurements ◽  
Mean Difference ◽  
Time Interval ◽  
Rater Agreement ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Significant Difference ◽  
Two Indices

Abstract Background Instantaneous wave-free ratio (iFR) has been recently introduced as an adenosine free alternative for fractional flow reserve (FFR) to assess the functional significance of epicardial coronary stenosis. Little is known, however, regarding the repeatability and stability of iFR in comparison with FFR. Purpose The aim of this study was to evaluate the repeatability of iFR and compare it to that of FFR. Methods Patients with stable coronary artery disease who underwent physiological assessment twice within 90 days were enrolled. Repeated measurements were performed at diagnostic and therapeutic catheterization in about 70% of studied population. The remaining patients were measured twice for non-culprit lesion assessment at primary PCI and subsequent non-culprit and ischemia-documented lesion PCI. The calculation of iFRmatlab from DICOM pressure tracing data of resting state was performed using a fully automated off-line software algorithm in a blind fashion. FFR values were also measured by a fully automated algorithm in the same core laboratory by using hyperemic pressure tracing data. The repeatability of the two indices were evaluated and compared. The inter-rater agreement between iFRmatlab and FFR values of two measurements was assessed by κ coefficient. The pressure rate product during each assessment was also documented and evaluated. Results Ninety-three lesions from 92 patients were included in the study. The time interval between the two assessments was 38.4±19.0 days. iFRmatlab and FFR both showed significant correlation within the two assessments (iFRmatlab: r=0.75, 95% confidence interval, 0.64 to 0.83; mean difference, −0.006 [−0.18 to −0.01], FFR: r=0.86, 95% confidence interval, 0.79 to 0.90; mean difference, 0.004 [−0.07 to 0.03]). The inter-rater agreement of functional ischemia for iFRmatlab and FFR were κ=0.449 and κ=0.732, respectively. Although the prevalence of functional ischemia during the first and second assessment were consistent for both indices (iFRmatlab: 70.0%/67.7%, FFR: 86.0%/ 86.0%), significant difference was observed in the prevalence of clinical disagreement on the diagnosis of functional ischemia (FFR=0.80, iFR=0.89 used as cut-off values, respectively) between the first and second assessment among the two indices (iFRmatlab: 6.5%, FFR: 23.7%, p=0.002). iFRmatlab was significantly associated with pressure rate product during the examination compared to FFR (iFRmatlab: r= −0.25, 95% confidence interval, −0.43 to −0.04, P=0.018, FFR: r=−0.08, 95% confidence interval, −0.28 to −0.13, p=0.467). Conclusion Our results suggested that iFRmatlab showed lower repeatability and reliability for decision making compared to FFR. The instability of iFRmatlab potentially derives at least in part from its association with heart rate and blood pressure product.

Abstract 12632: Impact of Systolic Pressure Response on Measurement of Fractional Flow Reserve

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Tomoyuki Ikeda ◽  
Masafumi Ueno ◽  
Shinichiro Ikuta ◽  
Kosuke Fujita ◽  
Masakazu Yasuda ◽  
...  
Keyword(s):  
Coronary Arteries ◽  
Fractional Flow Reserve ◽  
Cardiac Cycle ◽  
Systolic Pressure ◽  
Pressure Response ◽  
The Other ◽  
Fractional Flow ◽  
Diastolic Phase ◽  
Flow Reserve ◽  
Significant Difference

Background: Fractional flow reserve (FFR) is calculated as the ratio between distal coronary pressure(Pd)and aortic pressure(Pa)during whole cardiac cycle at stable hyperemia. In clinical practice, we experience various Pd wave pattern during hyperemia, such as decreasing equally in systolic and diastolic phase, or mainly decreasing in diastolic phase. Purpose: The aim of the study was to evaluate the impact of systolic and diastolic pressure response during hyperemia in patients with coronary stenosis and an FFR of less than 0.8. Methods: A total of 35 patients (40 stenosis)had FFR of less than 0.8 were enrolled. FFR measurements were performed using a standard technique. Based on Pa and Pd wave forms, the decreasing area in systolic and diastolic were calculated by integrating Pa-Pd pressure gradient during hyperemia using the RadiView2.2 software. %Sys value was defined as the percentage of delta systolic area during the whole cardiac cycle (Figure). The results of %Sys values were divided into tertiles to evaluate the most significant factors for systolic pressure response. Results: Vessel distribution was as follows: LAD (60%), CX (20%) and RCA (20%). There was a significant difference of vessel distribution in coronary arteries in the upper tertile compared with the other two tertiles of %Sys values (p=0.028). However, the other factors such as FFR value, lesion length and severity, history of diabetes mellitus and previous myocardial infraction were not affected by the %Sys values. In addition, there was a significant difference of %Sys values among three major coronary arteries (LAD 49.4±18.5%, CX 81.5±38.7%, RCA 67.5±20.2%, p=0.006). %Sys values were significantly higher in non-LAD lesions compared with LAD lesions (74.5±30.7% vs 49.4±18.5%, p=0.003). Conclusions: There was a significant difference of decreasing pattern of Pd wave during hyperemia among the three coronary arteries. These findings suggest that iFR might not be accurate in non-LAD lesion.

scholarly journals The reasons why fractional flow reserve and instantaneous wave-free ratio are similar using wave separation analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Soohong Min ◽  
Gwansuk Kang ◽  
Dong-Guk Paeng ◽  
Joon Hyouk Choi
Keyword(s):  
Fractional Flow Reserve ◽  
Circulation System ◽  
Fractional Flow ◽  
Wave Separation ◽  
Flow Reserve ◽  
Stenosis Severity ◽  
The Relationship ◽  
Wedge Pressure

Abstract Background and objectives Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are the two most commonly used coronary indices of physiological stenosis severity based on pressure. To minimize the effect of wedge pressure (Pwedge), FFR is measured during hyperemia conditions, and iFR is calculated as the ratio of distal and aortic pressures (Pd/Pa) in the wave-free period. The goal of this study was to predict Pwedge using the backward wave (Pback) through wave separation analysis (WSA) and to reflect the effect of Pwedge on FFR and iFR to identify the relationship between the two indices. Methods An in vitro circulation system was constructed to calculate Pwedge. The measurements were performed in cases with stenosis percentages of 48, 71, and 88% and with hydrostatic pressures of 10 and 30 mmHg. Then, the correlation between Pback by WSA and Pwedge was calculated. In vivo coronary flow and pressure were simultaneously measured for 11 vessels in all patients. The FFR and iFR values were reconstructed as the ratios of forward wave at distal and proximal sites during hyperemia and at rest, respectively. Results Based on the in vitro results, the correlation between Pback and Pwedge was high (r = 0.990, p < 0.0001). In vivo results showed high correlations between FFR and reconstructed FFR (r = 0.992, p < 0.001) and between iFR and reconstructed iFR (r = 0.930, p < 0.001). Conclusions Reconstructed FFR and iFR were in good agreement with conventional FFR and iFR. FFR and iFR can be expressed as the variation of trans-stenotic forward pressure, indicating that the two values are inferred from the same formula under different conditions.

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.

scholarly journals Non-randomized comparison between revascularization and deferral for intermediate coronary stenosis with abnormal fractional flow reserve and preserved coronary flow reserve

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Doosup Shin ◽  
Joo Myung Lee ◽  
Seung Hun Lee ◽  
Doyeon Hwang ◽  
Ki Hong Choi ◽  
...  
Keyword(s):  
Coronary Flow Reserve ◽  
Fractional Flow Reserve ◽  
International Collaboration ◽  
Coronary Stenosis ◽  
Coronary Flow ◽  
Target Vessel ◽  
Fractional Flow ◽  
Patient Level ◽  
Flow Reserve ◽  
Significant Difference

AbstractLimited data are available regarding comparative prognosis after percutaneous coronary intervention (PCI) versus deferral of revascularization in patients with intermediate stenosis with abnormal fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). From the International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713), a total of 330 patients (338 vessels) who had coronary stenosis with FFR ≤ 0.80 but CFR > 2.0 were selected for the current analysis. Patient-level clinical outcome was assessed by major adverse cardiac events (MACE) at 5 years, a composite of all-cause death, target-vessel myocardial infarction (MI), or target-vessel revascularization. Among the study population, 231 patients (233 vessels) underwent PCI and 99 patients (105 vessels) were deferred. During 5 years of follow-up, cumulative incidence of MACE was 13.0% (31 patients) without significant difference between PCI and deferred groups (12.7% vs. 14.0%, adjusted HR 1.301, 95% CI 0.611–2.769, P = 0.495). Multiple sensitivity analyses by propensity score matching and inverse probability weighting also showed no significant difference in patient-level MACE and vessel-specific MI or revascularization. In this hypothesis-generating study, there was no significant difference in clinical outcomes between PCI and deferred groups among patients with intermediate stenosis with FFR ≤ 0.80 but CFR > 2.0. Further study is needed to confirm this finding.Clinical Trial Registration: International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713; registration date: 10/01/2018).

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