Minimal effect of collateral flow on coronary microvascular resistance in the presence of intermediate and noncritical coronary stenoses

2012 ◽  
Vol 303 (4) ◽  
pp. H422-H428 ◽  
Author(s):  
Bart-Jan Verhoeff ◽  
Tim P. van de Hoef ◽  
Jos A. E. Spaan ◽  
Jan J. Piek ◽  
Maria Siebes
Keyword(s):  
Wall Stress ◽  
Coronary Intervention ◽  
Relative Difference ◽  
Collateral Flow ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Before And After ◽  
Stenosis Severity ◽  
Microvascular Resistance ◽  
Relevant Range

Depending on stenosis severity, collateral flow can be a confounding factor in the determination of coronary hyperemic microvascular resistance (HMR). Under certain assumptions, the calculation of HMR can be corrected for collateral flow by incorporating the wedge pressure (Pw) in the calculation. However, although Pw > 25 mmHg is indicative of collateral flow, Pw does in part also reflect myocardial wall stress neglected in the assumptions. Therefore, the aim of this study was to establish whether adjusting HMR by Pw is pertinent for a diagnostically relevant range of stenosis severities as expressed by fractional flow reserve (FFR). Accordingly, intracoronary pressure and Doppler flow velocity were measured a total of 95 times in 29 patients distal to a coronary stenosis before and after stepwise percutaneous coronary intervention. HMR was calculated without (HMR) and with Pw-based adjustment for collateral flow (HMRC). FFR ranged from 0.3 to 1. HMR varied between 1 and 5 and HMRC between 0.5 and 4.2 mmHg·cm−1·s. HMR was about 37% higher than HMRC for stenoses with FFR < 0.6, but for FFR > 0.8, the relative difference was reduced to 4.4 ± 3.4%. In the diagnostically relevant range of FFR between 0.6 and 0.8, this difference was 16.5 ± 10.4%. In conclusion, Pw-based adjustment likely overestimates the effect of potential collateral flow and is not needed for the assessment of coronary HMR in the presence of a flow-limiting stenosis characterized by FFR between 0.6 and 0.8 or for nonsignificant lesions.

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.

scholarly journals Prospective Evaluation of the Strategy of Functionally Optimized Coronary Intervention

2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Barry F. Uretsky ◽  
Shiv K Agarwal ◽  
Srikanth Vallurupalli ◽  
Malek Al‐Hawwas ◽  
Rimsha Hasan ◽  
...  
Keyword(s):  
Coronary Intervention ◽  
Interquartile Range ◽  
Fractional Flow ◽  
Long Term Outcomes ◽  
Flow Reserve ◽  
Pressure Wire ◽  
Percutaneous Coronary ◽  
Before And After ◽  
The Impact

Background Long‐term outcomes after percutaneous coronary intervention (PCI) relate in part to residual ischemia in the treated vessel, as reflected by post‐PCI fractional flow reserve (FFR). The strategy of FFR after PCI and treatment of residual ischemia—known as functionally optimized coronary intervention (FCI)—may be feasible and capable of improving outcomes. Methods and Results Feasibility and results of FCI using an optical‐sensor pressure wire were prospectively evaluated in an all‐comer population with 50% to 99% lesions and ischemic FFR (≤0.80; ClinicalTrials.gov identifier NCT03227588). FCI was attempted in 250 vessels in 226 consecutive patients. The PCI success rate was 99.6% (249/250 vessels). FCI technical success—that is, FFR before and after PCI and PCI itself using the FFR wire—was 92% (230/250 vessels). Incidence of residual ischemia in the treated vessel was 36.5%. Approximately a third of these vessels (34.5%, n=29) were considered appropriate for further intervention, with FFR increasing from 0.71±0.07 to 0.81±0.06 ( P <0.001). Pressure wire pullback showed FFR ≤0.8 at distal stent edge was 7.9% and 0.7% proximal to the stent. FFR increase across the stent was larger in the ischemic than in the nonischemic group (0.06 [interquartile range: 0.04–0.08] versus 0.03 [interquartile range: 0.01–0.05]; P <0.0001) compatible with stent underexpansion as a contributor to residual ischemia. Conclusions FCI is a feasible and safe clinical strategy that identifies residual ischemia in a large proportion of patients undergoing angiographically successful PCI. Further intervention can improve ischemia. The impact of this strategy on long‐term outcomes needs further study.

Misinterpretation of Functional Severity of Coronary Stenosis in the Presence of Collateral Flow

2008 ◽  
Author(s):  
Srikara Viswanath Peelukhana ◽  
Rupak K. Banerjee ◽  
Mohamed A. Effat ◽  
Tarek Helmy
Keyword(s):  
Cardiac Catheterization ◽  
Coronary Stenosis ◽  
Threshold Value ◽  
Coronary Intervention ◽  
Collateral Flow ◽  
Diagnostic Parameter ◽  
Fractional Flow ◽  
Myocardial Diseases ◽  
Flow Reserve ◽  
Percutaneous Coronary

Angiography is widely used diagnostic method to find the ischemic severity. However, it is limited in its capacity in determining the functional severity of the stenosis [1]. Hence, a functional diagnostic parameter Fractional Flow Reserve (FFR), defined as the ratio of distal pressure to the proximal pressure at maximum vasodilation [2], at the site of the stenosis, was developed to assess the functional severity of the stenosis. Pijls et al [3], established a threshold value of 0.75 for FFR, based on which coronary intervention decisions are taken. If FFR is below 0.75, a percutaneous coronary intervention is recommended. FFR is calculated during cardiac catheterization by measuring the pressure values across the stenosis. However, the value of FFR measured during cardiac catheterization doesn’t account for the increase in pressure values downstream of stenosis, due to other resistances in coronary circuit, e.g., abnormal microvasculature and functional collaterals, as it cannot delineate the effect of downstream collateral flow or the presence of myocardial diseases.

scholarly journals Coronary physiology before and after chronic total occlusion treatment: what does it tell us?

2020 ◽  
Vol 29 (1) ◽  
pp. 22-29 ◽  
Author(s):  
D. C. J. Keulards ◽  
P. J. Vlaar ◽  
I. Wijnbergen ◽  
N. H. J. Pijls ◽  
K. Teeuwen
Keyword(s):  
Coronary Artery ◽  
Chronic Total Occlusion ◽  
Coronary Intervention ◽  
Fractional Flow ◽  
Total Occlusion ◽  
Flow Reserve ◽  
Donor Artery ◽  
Before And After ◽  
Over Time

AbstractStudies performed in the last two decades demonstrate that after successful percutaneous coronary intervention (PCI) of a chronically occluded coronary artery, the physiology of the chronic total occlusion (CTO) vessel and dependent microvasculature does not normalise immediately but improves significantly over time. Generally, there is an increase in fractional flow reserve (FFR) in the CTO artery, a decrease in collateral blood supply and an increase in FFR in the donor artery accompanied by an increase in blood flow and decrease in microvascular resistance in the myocardium supplied by the CTO vessel. Analogous to these physiological changes, positive remodelling of the distal CTO artery also occurs over time, and intravascular imaging can be helpful for analysing distal vessel parameters. Follow-up coronary angiography with physiological measurements after several weeks to months can be helpful and informative in a subset of patients in order to decide upon the necessity for treatment of residual coronary artery stenosis in the vessel distal to the CTO or in the contralateral donor artery, as well as in deciding whether stent optimisation is indicated. We suggest that such physiological guidance of CTO procedures avoids unnecessary overtreatment during the initial procedure, guides interventions at follow-up, and improves our understanding of what PCI in CTO means.

Influence of hemodynamic conditions on fractional flow reserve: parametric analysis of underlying model

2002 ◽  
Vol 283 (4) ◽  
pp. H1462-H1470 ◽  
Author(s):  
Maria Siebes ◽  
Steven A. J. Chamuleau ◽  
Martijn Meuwissen ◽  
Jan J. Piek ◽  
Jos A. E. Spaan
Keyword(s):  
Fractional Flow Reserve ◽  
Aortic Pressure ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Stenosis Severity ◽  
In Series ◽  
Resistive Model ◽  
Epicardial Stenosis ◽  
Microvascular Resistance ◽  
Diameter Reduction

Pressure-based fractional flow reserve (FFR) is used clinically to evaluate the functional severity of a coronary stenosis, by predicting relative maximal coronary flow (Qs/Qn). It is considered to be independent of hemodynamic conditions, which seems unlikely because stenosis resistance is flow dependent. Using a resistive model of an epicardial stenosis (0–80% diameter reduction) in series with the coronary microcirculation at maximal vasodilation, we evaluated FFR for changes in coronary microvascular resistance ( R cor= 0.2–0.6 mmHg · ml−1 · min), aortic pressure (Pa = 70–130 mmHg), and coronary outflow pressure (Pb = 0–15 mmHg). For a given stenosis, FFR increased with decreasing Pa or increasing R cor. The sensitivity of FFR to these hemodynamic changes was highest for stenoses of intermediate severity. For Pb > 0, FFR progressively exceeded Qs/Qn with increasing stenosis severity unless Pb was included in the calculation of FFR. Although the Pb-corrected FFR equaled Qs/Qn for a given stenosis, both parameters remained equally dependent on hemodynamic conditions, through their direct relationship to both stenosis and coronary resistance.

scholarly journals The FAME Trials: Impact on Clinical Decision Making

2016 ◽  
Vol 11 (2) ◽  
pp. 116 ◽  
Author(s):  
Guy R Heyndrickx ◽  
Gábor G Tóth ◽  
◽  
Keyword(s):  
Medical Treatment ◽  
Fractional Flow Reserve ◽  
Clinical Decision Making ◽  
Stable Coronary Artery Disease ◽  
Coronary Intervention ◽  
Clinical Decision ◽  
Fractional Flow ◽  
Flow Reserve ◽  
Stenosis Severity ◽  
Artery Disease

Careful and stepwise evaluation of the fractional flow reserve (FFR) index has been performed over the years, culminating in the landmark Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) and Fractional Flow Reserve-Guided Percutaneous Coronary Intervention Plus Optimal Medical Treatment Versus Optimal Medical Treatment Alone in Patients with Stable Coronary Artery Disease (FAME II) trials. Findings from these studies demonstrated unequivocally the overall inadequacy of angiography versus FFR to correctly assess stenosis severity. Thus, proof of concept and clinical applicability was established beyond debate and will be discussed here.

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

2013 ◽  
Vol 305 (2) ◽  
pp. H145-H154 ◽  
Author(s):  
Dotan Algranati ◽  
Ghassan S. Kassab ◽  
Yoram Lanir
Keyword(s):  
Venous Pressure ◽  
Coronary Intervention ◽  
Aortic Pressure ◽  
Lesion Length ◽  
Fractional Flow ◽  
Inducible Ischemia ◽  
Flow Reserve ◽  
Flow Restoration ◽  
Stenosis Severity ◽  
Index Level

The expected blood flow improvement following a coronary intervention is inversely related to the stenotic-to-normal flow ratio Qs/Qn. Since Qn 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 Qs/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 Qs/Qn. Under each perturbation, an independence measure (IM) was calculated for each index based on the relative change in Qs/Qn associated with each perturbation. The results show that while %AS prediction of Qs/Qn is largely independent (IM > 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 Qs/Qn is also independent of changes in aortic pressure, blood hematocrit, and stenotic vessel stiffness. Nevertheless, independence of all indexes is substantially compromised (IM < 70%) under changes in vasculature stiffness. Specifically, a physiological stiffening elevates Qs/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).

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