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 Heart Rate and Area Stenosis on Coronary Diagnostic Parameters in a Porcine Model

2009 ◽  
Author(s):  
Kranthi Kumar Kolli ◽  
Srikara V. Peelukhana ◽  
Mohamed Effat ◽  
Tarek Helmy ◽  
Massoud Leesar ◽  
...  
Keyword(s):  
Heart Rate ◽  
Dynamic Pressure ◽  
Aortic Pressure ◽  
Fractional Flow ◽  
Diagnostic Parameters ◽  
In Vivo Experiments ◽  
Flow Reserve ◽  
Mean Pressure ◽  
Yorkshire Pigs

Several parameters have been proposed to assess the physiologic significance of coronary lesions invasively. The purpose of the present study is to determine the effect of heart rate and percentage area stenosis on Fractional Flow Reserve (FFR), which is the ratio of mean pressure distal to stenosis over the mean proximal (aortic) pressure and Pressure Drop Coefficient (CDP), ratio of trans-stenotic pressure gradient to distal dynamic pressure. In-vivo experiments were performed on three Yorkshire pigs, to achieve the objective. It was found that increase in heart rate does have a significant effect on the coronary diagnostic parameters with increase in area stenosis.

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.

Influence of Heart Rate and Epicardial Stenosis Severity on Cardiac Contractility Under Concomitant Microvascular Disease in a Porcine Model

2011 ◽  
Author(s):  
Srikara V. Peelukhana ◽  
Kranthi K. Kolli ◽  
William Gottliebson ◽  
Massoud Leesar ◽  
Tarek Helmy ◽  
...  
Keyword(s):  
Heart Rate ◽  
Guide Wire ◽  
Cardiac Contractility ◽  
Microvascular Disease ◽  
In Vivo Experiments ◽  
Stenosis Severity ◽  
Yorkshire Pigs ◽  
Epicardial Stenosis ◽  
Dynamic Variables

Invasive guide wire methods to assess functional severity of coronary stenosis are affected by dynamic variables like heart rate (HR), contractility, epicardial stenosis (AS) and blood pressure. The interdependence of these factors is also influenced by the presence of concomitant microvascular disease (CMVD). The purpose of this study is to assess the variation in contractility under varying HR and AS in the presence of CMVD. In vivo experiments were performed on seven Yorkshire pigs. It was found that, in the presence of concomitant microvascular disease (CMVD), for lower AS (<50%) contractility increases for HR<120 bpm while it marginally decreases for HR>120 bpm. However, for higher AS (>50%), contractility decreases for both HR<120 bpm and HR>120 bpm.

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.

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.

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).

Influence of contractility and heart rate on pressure drop coefficient and fractional flow reserve for epicardial stenosis

2010 ◽  
Vol 11 (3) ◽  
pp. 214 ◽  
Author(s):  
Kranthi K. Kolli ◽  
Tarek Helmy ◽  
Mohamed Effat ◽  
Arif Imran ◽  
Massoud Leesar ◽  
...  
Keyword(s):  
Heart Rate ◽  
Pressure Drop ◽  
Fractional Flow Reserve ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Epicardial Stenosis

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.

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