The diastolic flow-pressure gradient relation in coronary stenoses in humans

Marques, Koen M.; Spruijt, H.J.; Boer, Christa; Westerhof, Nico; Visser, Cees A.; Visser, Frans C.

doi:10.1016/s0735-1097(02)01834-x

Cited by 45 publications

(32 citation statements)

References 17 publications

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“…Over the years, many other indices, such as translesional coronary flow velocity, 40 slope of the instantaneous hyperemic diastolic coronary flow velocity-pressure relation, 41 diastolic FFR, 42 pulse transmission coefficient, 43 diastolic flow velocitypressure gradient relation, 44 hyperemic stenosis resistance, 45 coronary pressure notch, 46 pressure drop coefficient, 47 lesion flow coefficient, 47 and basal stenosis resistance 48 have been proposed for evaluating the physiological significance of intermediate coronary artery stenoses. However, none of these has gained widespread use either because of measurement complexity, lack of data supporting their use, or lack of any substantial advantage for FFR.…”

Section: Other Proposed Indexesmentioning

confidence: 99%

Invasive Coronary Physiology for Assessing Intermediate Lesions

Fearon

2015

Circ: Cardiovascular Interventions

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Section: Other Proposed Indexesmentioning

confidence: 99%

Invasive Coronary Physiology for Assessing Intermediate Lesions

Fearon

2015

Circ: Cardiovascular Interventions

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“…36 However, interpretation of these diastolic aortic pressurecoronary flow relations is hampered by the superimposed hemodynamic effects of microcirculation and stenosis that can be overcome with modern guidewire technology measuring pressure and velocity distal to a stenosis simultaneously. 3,38 …”

Section: Diastolic Coronary Pressure-flow Relationsmentioning

confidence: 99%

Physiological Basis of Clinically Used Coronary Hemodynamic Indices

et al. 2006

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Abstract-In deriving clinically used hemodynamic indices such as fractional flow reserve and coronary flow velocity reserve, simplified models of the coronary circulation are used. In particular, myocardial resistance is assumed to be independent of factors such as heart contraction and driving pressure. These simplifying assumptions are not always justified. In this review we focus on distensibility of resistance vessels, the shape of coronary pressure-flow lines, and the influence of collateral flow on these lines. We show that (1) the coronary system is intrinsically nonlinear because resistance vessels at maximal vasodilation change diameter with pressure and cardiac function; (2) the assumption of collateral flow is not needed to explain the difference between pressure-derived and flow-derived fractional flow reserve; and (3) collateral flow plays a role only at low distal pressures. We conclude that traditional hemodynamic indices are valuable for clinical decision making but that clinical studies of coronary physiology will benefit greatly from combined measurements of coronary flow or velocity and pressure. Key Words: blood flow velocity Ⅲ blood pressure Ⅲ collateral circulation Ⅲ coronary disease Ⅲ hemodynamics C oronary physiology has a rich history, founded on numerous animal and theoretical models, and significant milestones were reached as new measuring techniques were developed. Recent progress has been made by applying techniques to measure intracoronary flow, flow velocity, and pressure to aid in clinical decision making, thereby advancing our understanding of human coronary physiology beyond what could be extrapolated from animal studies. One unresolved issue that has arisen from these studies, however, concerns conflicting interpretations of coronary microvascular resistance, a quantity with crucial relevance for clinical decision making. [1][2][3][4] There are 2 conflicting interpretations of coronary pressure-flow lines during hyperemia: (1) coronary pressureflow relations are straight and, in the absence of collateral flow, intercept the pressure axis at venous pressure (Pv); or (2) coronary pressure-flow relations are straight at physiological pressures and, when linearly extrapolated, intercept the pressure axis at a value well above venous pressure (extrapolated zero flow pressure [PzfE]); at lower pressures, however, they curve toward the pressure axis, intercepting it at a lower pressure (actual zero flow pressure [Pzf]) that is still higher than Pv.The purpose of this article is to review the physiological literature with respect to coronary pressure-flow relations as relevant to myocardial microvascular resistance. This key issue relates to important assumptions underlying the frequently used model of myocardial fractional flow reserve (FFR myo ). We conclude with a synopsis of physiological studies demonstrating the curved nature of pressure-flow relations and how this shape relates to the pressure dependence of minimal coronary microvascular resistance.This focused review of coronar...

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“…The relationship between these indexes' values and Q s /Q n level is presently unknown. Furthermore, for a given index value the flow ratio Q s /Q n may be affected by hemodynamic and mechanical determinants of the downstream microcirculatory flow (29,39), such as heart rate (HR), blood pressure, and contractile state, which may vary during interventional procedures (6). Assessment of Q s /Q n should ideally be independent of changes in hemodynamic loading and myocardial function.…”

mentioning

confidence: 99%

Flow restoration post revascularization predicted by stenosis indexes: sensitivity to hemodynamic variability

Algranati

Kassab

Lanir

2013

American Journal of Physiology-Heart and Circulatory Physiology

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Algranati D, Kassab GS, Lanir Y. Flow restoration post revascularization predicted by stenosis indexes: sensitivity to hemodynamic variability. Am J Physiol Heart Circ Physiol 305: H145-H154, 2013. First published May 3, 2013 doi:10.1152/ajpheart.00061.2012The expected blood flow improvement following a coronary intervention is inversely related to the stenotic-to-normal flow ratio Q s/Qn. Since Q n cannot be measured prior to intervention, treatment decisions rely on stenosis-severity indexes, e.g., area stenosis (%AS), hyperemic stenosis resistance (HSR), and fractional flow reserve (FFR), where treatment cut-off levels have been established for each index based on presence of inducible ischemia. Here, we studied the dependence of these indexes-predicted Q s/Qn under physiological perturbations of stenosis features and of hemodynamic and mechanical conditions. Dynamic coronary flow was simulated based on measured coronary morphometric data and a physics-based computational model. Simulations were used to evaluate the relationship between each index level and Q s/Qn. Under each perturbation, an independence measure (IM) was calculated for each index based on the relative change in Q s/Qn associated with each perturbation. The results show that while %AS prediction of Q s/Qn is largely independent (IM Ͼ 90%) of physiological changes in heart rate, venous pressure, and lesion length and location on the epicardial tree, HSR is also independent of changes in left ventricle pressure. FFR-predicted Q s/Qn is also independent of changes in aortic pressure, blood hematocrit, and stenotic vessel stiffness. Nevertheless, independence of all indexes is substantially compromised (IM Ͻ 70%) under changes in vasculature stiffness. Specifically, a physiological stiffening elevates Q s/Qn value by 21% at the FFR cut-off value (0.75). These findings suggest that the current FFR cut-off value for treatment of stenotic lesions overestimates the benefit of coronary intervention in patients with a stiffer coronary vasculature (e.g., diabetics, hypertensives). myocardial ischemia; flow restoration; clinical assessment; hemodynamic effects; model simulation; fractional flow reserve; hyperemic stenosis resistance THE GOAL OF CORONARY INTERVENTION is to treat the lesion in order to restore normal blood flow (Q n ) of a stenotic vessel flow (Q s ). The Q s /Q n ratio represents the anticipated hyperemic flow restoration postrevascularization. Unfortunately, Q s /Q n cannot be quantified a priori since Q n is unknown prior to intervention. Hence the clinical choice of treatment strategy, whether drug administration, percutaneous coronary interventions (PCI), or coronary artery bypass grafts (CABG), is based on indirect indexes of stenosis severity. Some of the current indexes (e.g., absolute and relative coronary flow reserve, CFR and rCFR, respectively) depend on the state of coronary vasoactivity (autoregulation), which can be quite variable. Hence, the present study focuses on the most common hyperemic (full vasodilation) indexes, su...

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The diastolic flow-pressure gradient relation in coronary stenoses in humans

Abstract: It is feasible to assess the diastolic flow velocity-pressure gradient relation over a wide range of stenoses. It characterizes the hemodynamics of epicardial coronary stenoses and allows discrimination between normal coronary arteries, intermediate and severe stenoses.

Cited by 45 publications

References 17 publications

Invasive Coronary Physiology for Assessing Intermediate Lesions

Invasive Coronary Physiology for Assessing Intermediate Lesions

Physiological Basis of Clinically Used Coronary Hemodynamic Indices

Flow restoration post revascularization predicted by stenosis indexes: sensitivity to hemodynamic variability

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