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).

Effect of heart rate on hemodynamic endpoints under concomitant microvascular disease in a porcine model

2012 ◽  
Vol 302 (8) ◽  
pp. H1563-H1573 ◽  
Author(s):  
S. V. Peelukhana ◽  
R. K. Banerjee ◽  
K. K. Kolli ◽  
M. A. Effat ◽  
T. A. Helmy ◽  
...  
Keyword(s):  
Heart Rate ◽  
Pressure Drop ◽  
Dynamic Pressure ◽  
Microvascular Disease ◽  
Flow Coefficient ◽  
Fractional Flow ◽  
Anova Analysis ◽  
Throat Region ◽  
Flow Reserve ◽  
Yorkshire Pigs

Diagnosis of the ischemic power of epicardial stenosis with concomitant microvascular disease (MVD) is challenging during coronary interventions, especially under variable hemodynamic factors like heart rate (HR). The goal of this study is to assess the influence of variable HR and percent area stenosis (%AS) in the presence of MVD on pressure drop coefficient (CDP; ratio of transstenotic pressure drop to the distal dynamic pressure) and lesion flow coefficient (LFC; ratio of %AS to the CDP at the throat region). We hypothesize that CDP and LFC are independent of HR. %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop (DP) and velocity were done in 11 Yorkshire pigs. Fractional flow reserve (FFR), CDP, and LFC were calculated for the groups HR < 120 and HR > 120 beats/min, %AS < 50 and %AS > 50, and additionally for DP < 14 and DP > 14 mmHg, and analyzed using regression and ANOVA analysis. Regression analysis showed independence between HR and the FFR, CDP, and LFC while it showed dependence between %AS and the FFR, CDP, and LFC. In the ANOVA analysis, for the HR < 120 beats/min and HR > 120 beats/min groups, the values of FFR (0.82 ± 0.02 and 0.82 ± 0.02), CDP (83.15 ± 26.19 and 98.62 ± 26.04), and LFC (0.16 ± 0.03 and 0.15 ± 0.03) were not significantly different ( P > 0.05). However, for %AS < 50 and %AS > 50, the FFR (0.89 ± 0.02 and 0.75 ± 0.02), CDP (35.97 ± 25.79.10 and 143.80 ± 25.41), and LFC (0.09 ± 0.03 and 0.22 ± 0.03) were significantly different ( P < 0.05). A similar trend was observed between the DP groups. Under MVD conditions, FFR, CDP, and LFC were not significantly influenced by changes in HR, while they can significantly distinguish %AS and DP groups.

Distinguishing Epicardial and Microvascular Disease Using Combined Functional and Anatomical Endpoints in a Porcine Model

2012 ◽  
Author(s):  
Srikara V. Peelukhana ◽  
Kranthi K. Kolli ◽  
Massoud Leesar ◽  
Mohamed Effat ◽  
Tarek Helmy ◽  
...  
Keyword(s):  
Resistance Index ◽  
Microvascular Disease ◽  
Flow Coefficient ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Artery Disease ◽  
Lesion Flow Coefficient ◽  
Epicardial Stenosis ◽  
The Individual ◽  
Concurrent Assessment

For a better treatment of coronary artery disease in a catheterization lab, detection of the relative contributions of the epicardial stenosis (ES) and concomitant microvascular disease (MVD) is important. To diagnose ES, fractional flow reserve (FFR), the hyperemic stenosis resistance index (hSRv) and to diagnose MVD, hyperemic microvascular resistance index (hMRv) have been tested in cath labs. However, for concurrent assessment of ES and MVD, functional parameter utilizing flow and pressure values, pressure drop coefficient (CDP) and combined functional and anatomical parameter, lesion flow coefficient (LFC) are defined. To test the ability of CDP and LFC to account for ES and MVD, they were correlated with the hSRv and hMRv. We hypothesize that CDP and LFC will have a better combined correlation with hSRv and hMRv. Simultaneous pressure and flow readings were obtained in 11 Yorkshire swine. Single and multiple linear regression analyses were conducted between the FFR, CDP and LFC vs hSRv and hMRv. The correlation coefficient (r) was used to check the strength of correlation. The individual correlation between hSRv and hMRV with CDP (r = 0.90; r = 0.78) and LFC (r = 0.89; r = 0.95) was stronger compared to FFR (r = 0.63; r = 0.32). The combined correlation between hSRv and hMRv with CDP (r = 0.95) and LFC (r = 0.95) increased from the individual correlation. Therefore, we conclude that CDP and LFC can diagnose ES and MVD concurrently and might prove to be improved diagnostic parameters than FFR.

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.

Influence of heart rate on fractional flow reserve, pressure drop coefficient, and lesion flow coefficient for epicardial coronary stenosis in a porcine model

2011 ◽  
Vol 300 (1) ◽  
pp. H382-H387 ◽  
Author(s):  
Kranthi K. Kolli ◽  
R. K. Banerjee ◽  
Srikara V. Peelukhana ◽  
T. A. Helmy ◽  
M. A. Leesar ◽  
...  
Keyword(s):  
Heart Rate ◽  
Pressure Drop ◽  
Fractional Flow Reserve ◽  
Coronary Stenosis ◽  
Flow Coefficient ◽  
Fractional Flow ◽  
Mean Values ◽  
Flow Reserve ◽  
The Mean ◽  
Lesion Flow Coefficient

A limitation in the use of invasive coronary diagnostic indexes is that fluctuations in hemodynamic factors such as heart rate (HR), blood pressure, and contractility may alter resting or hyperemic flow measurements and may introduce uncertainties in the interpretation of these indexes. In this study, we focused on the effect of fluctuations in HR and area stenosis (AS) on diagnostic indexes. We hypothesized that the pressure drop coefficient (CDPe, ratio of transstenotic pressure drop and distal dynamic pressure), lesion flow coefficient (LFC, square root of ratio of limiting value CDP and CDP at site of stenosis) derived from fluid dynamics principles, and fractional flow reserve (FFR, ratio of average distal and proximal pressures) are independent of HR and can significantly differentiate between the severity of stenosis. Cardiac catheterization was performed on 11 Yorkshire pigs. Simultaneous measurements of distal coronary arterial pressure and flow were performed using a dual sensor-tipped guidewire for HR < 120 and HR > 120 beats/min, in the presence of epicardial coronary lesions of <50% AS and >50% AS. The mean values of FFR, CDPe, and LFC were significantly different ( P < 0.05) for lesions of <50% AS and >50% AS (0.88 ± 0.04, 0.76 ± 0.04; 62 ± 30, 151 ± 35, and 0.10 ± 0.02 and 0.16 ± 0.01, respectively). The mean values of FFR and CDPe were not significantly different ( P > 0.05) for variable HR conditions of HR < 120 and HR > 120 beats/min (FFR, 0.81 ± 0.04 and 0.82 ± 0.04; and CDPe, 95 ± 33 and 118 ± 36). The mean values of LFC do somewhat vary with HR (0.14 ± 0.01 and 0.12 ± 0.02). In conclusion, fluctuations in HR have no significant influence on the measured values of CDPe and FFR but have a marginal influence on the measured values of LFC. However, all three parameters can significantly differentiate between stenosis severities. These results suggest that the diagnostic parameters can be potentially used in a better assessment of coronary stenosis severity under a clinical setting.

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).

Influence of Fractional Flow Reserve Setting on the Procedure Precision

2019 ◽  
Author(s):  
Yasser Abuouf ◽  
Shinichi Ookawara ◽  
Mahmoud Ahmed
Keyword(s):  
Fractional Flow Reserve ◽  
Dynamic Pressure ◽  
Treatment Plan ◽  
Accurate Method ◽  
Fractional Flow ◽  
Long Distance ◽  
Recovery Coefficient ◽  
Flow Reserve ◽  
Inclination Angles ◽  
Stenosis Severity

Abstract Coronary artery disease is the progressive narrowing (stenosis) of the heart supply arteries. Heart attack could occur as a consequence of severe blockage in the artery. A definitive diagnosis of its severity is of great importance for physicians to decide the best treatment plan. Fractional flow reserve (FFR) is a procedure that adopts a sensor tipped guidewire to measure upstream and downstream pressures of the stenosis. It is considered the most accurate method to pinpoint the stenosis severity. In this procedure, the centerlines of the guidewire and blood vessel should be aligned together. Due to the long distance between its insertion point and the stenosis, a possible inclination of the guidewire can occur. The aim of the present study is to investigate the effect of guidewire inclination on pressure measurements. Three different degrees of severity are modeled with placing the guidewire at different inclination angles. Continuity and momentum equations of blood flow are stated and computationally simulated. Comparisons between calculated and available measured values show a good agreement. The ratios between pressure drop and distal dynamic pressure (CDP), and between pressure recovery coefficient and the area blockage (η) are calculated. The predicted results for each case are compared with the control case (without guidewire) and analyzed. The results aid in improving the FFR accuracy in diagnosis of stenosis severity.

Epicardial coronary stenosis severity and myocardial perfusion

2020 ◽  
pp. 12-16
Keyword(s):  
Myocardial Perfusion ◽  
Myocardial Ischemia ◽  
Coronary Disease ◽  
Myocardial Perfusion Reserve ◽  
Pharmacological Intervention ◽  
Fractional Flow ◽  
Perfusion Reserve ◽  
Flow Reserve ◽  
Stenosis Severity ◽  
Microvascular Resistance

Patients suspected of having epicardial coronary disease are often investigated with noninvasive myocardial ischemia tests to establish a diagnosis and guide management. However, the relationship between myocardial ischemia and coronary stenoses is affected by multiple factors, and there is marked biological variation between patients. The ischemic cascade represents the temporal sequence of pathophysiological events that occur after interruption of myocardial oxygen delivery. The earliest part of the cascade is examined via perfusion imaging, and fractional flow reserve (FFR) is a corresponding index which is specific to the coronary artery. Whereas FFR has come to be regarded a clinical reference standard against which other newer invasive and noninvasive tests are validated, the diagnostic FFR threshold for detecting ischemia was established against a combination of noninvasive ischemia tests that assessed different stages of the ischemic cascade. Moreover, the validity of invasive pressure-derived indices of stenosis severity are contingent on the assumption that pressure is proportional to flow if microvascular resistance is constant, a condition induced by pharmacological intervention or by examining specific segments of the cardiac cycle. Furthermore, myocardial perfusion reserve depends on dynamic modulation of microvascular resistance, and dysfunction of the microvasculature can lead to ischemia even in the absence of epicardial coronary disease.

Abstract 19177: Loss of Coronary Perfusion Efficiency in Microvascular Disease

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Matthew Lumley ◽  
Matthew Ryan ◽  
Kaleab Asrress ◽  
Rupert Williams ◽  
Satpal Ari ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Coronary Flow ◽  
Microvascular Disease ◽  
Rate Pressure Product ◽  
Coronary Perfusion ◽  
Cardiac Events ◽  
Fractional Flow ◽  
Wave Separation ◽  
Flow Reserve ◽  
Response To Stress

Introduction: Coronary Microvascular Disease (MVD) is associated with an unfavorable prognosis, even in the absence of significant epicardial disease. The pathophysiological basis of increased cardiac events is unclear. The aim of this study was to characterize the forces that govern myocardial perfusion at rest and during stress. Methods: Patients with chest pain syndromes requiring Fractional Flow Reserve (FFR) assessment were screened and those with a FFR>0.80 were included. MVD was defined by coronary flow reserve (CFR) < 2.0. Controls were those with CFR>2.0. Simultaneous intracoronary pressure (P d ) and flow velocity (U) recordings were made at rest and hyperemia. Microvascular Resistance (MR)= P d /U. Wave intensity = dP d /dt x dU/dt and wave separation analysis was used to identify the waves that accelerate and decelerate flow. The proportional contribution of accelerating waves was assessed as an index of coronary perfusion efficiency. Results: 39 consecutive patients were enrolled, 21 had MVD and 18 comprised controls. The groups were matched for atherosclerotic risk factors, rate-pressure-product and P d . Coronary flow velocity in MVD patients was higher at rest (21.5±6.4 vs. 14.1±4.5cms -1 , p < 0.001) but lower during hyperemia (28.3±13.0 vs. 45.1±13.1cms -1 , p < 0.001) compared to controls. While resting MR was lower in MVD (501±162 vs. 755±262 mmHg.cm -1 .s, p = 0.001), hyperemic MR was significantly lower in controls. At rest the magnitude of the accelerating waves was higher in the MVD group than controls. The percentage contribution of accelerating waves increased with hyperemia in controls but decreased in MVD patients (figure). Conclusion: MVD manifests as resting microvascular dilation as well as diminished response to stress. While the normal heart has improved efficiency during hyperemia, in MVD efficiency decreases and as a result, flow augmentation is attenuated. These processes render the myocardium more susceptible to ischemia.

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