Quantification of fractional flow reserve based on angiographic image data

Wong, Jerry; Lê, Huy; Suh, William M.; Chalyan, David; Mehraien, Toufan; Kern, Morton J.; Kassab, Ghassan S.; Molloi, Sabee

doi:10.1007/s10554-010-9767-0

Cited by 23 publications

(22 citation statements)

References 37 publications

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“…The feasibility of predicting FFR using angiographic image data, where hyperemic flow is estimated from the crown volume based on a scaling law, has been evaluated in animal experiments (26). Initially, regional hyperemic flow in diseased coronary arteries was assessed by firstpass analysis of angiographic contrast and densitometric volume measurements of the arterial tree (9).…”

Section: Discussionmentioning

confidence: 99%

Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume

Horssen

Lier

Wijngaard

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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van Horssen P, van Lier MG, van den Wijngaard JP, VanBavel E, Hoefer IE, Spaan JA, Siebes M. Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume. Am J Physiol Heart Circ Physiol 310: H839 -H846, 2016. First published January 29, 2016 doi:10.1152/ajpheart.00728.2015.-Computational predictions of the functional stenosis severity from coronary imaging data use an allometric scaling law to derive hyperemic blood flow (Q) from coronary arterial volume (V), Q ϭ ␣V ␤ . Reliable estimates of ␣ and ␤ are essential for meaningful flow estimations. We hypothesize that the relation between Q and V depends on imaging resolution. In five canine hearts, fluorescent microspheres were injected into the left anterior descending coronary artery during maximal hyperemia. The coronary arteries of the excised heart were filled with fluorescent cast material, frozen, and processed with an imaging cryomicrotome to yield a three-dimensional representation of the coronary arterial network. The effect of limited image resolution was simulated by assessing scaling law parameters from the virtual arterial network at 11 truncation levels ranging from 50 to 1,000 m segment radius. Mapped microsphere locations were used to derive the corresponding relative Q using a reference truncation level of 200 m. The scaling law factor ␣ did not change with truncation level, despite considerable intersubject variability. In contrast, the scaling law exponent ␤ decreased from 0.79 to 0.55 with increasing truncation radius and was significantly lower for truncation radii above 500 m vs. 50 m (P Ͻ 0.05). Hyperemic Q was underestimated for vessel truncation above the reference level. In conclusion, flow-crown volume relations confirmed overall power law behavior; however, this relation depends on the terminal vessel radius that can be visualized. The scaling law exponent ␤ should therefore be adapted to the resolution of the imaging modality. FRACTIONAL FLOW RESERVE (FFR) has been shown to be a reliable and a widely accepted method to assess whether a coronary artery stenosis is responsible for myocardial ischemia (11). Conceptually, FFR is defined as the hyperemic flow in a vessel with a stenosis relative to the hypothetical hyperemic flow in the undiseased vessel. In practice, FFR is measured invasively as the ratio between pressure distal to a stenosis and aortic pressure, during adenosine-induced hyperemia. This requires passing of a guide wire with a pressure sensor through the stenosis. Despite the reliability of this method, risks of vessel and plaque rupture, procedure time, and costs have inspired the search for new less-invasive alternatives for assessing FFR (18), based on computational methods applied to arterial models obtained from angiography (27) or CT (6). By using experimentally established form-function relationships, coronary flow can be calculated from image-derived morphological data. These relationships are expressed in terms of allometric scaling laws r...

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Section: Discussionmentioning

confidence: 99%

Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume

Horssen

Lier

Wijngaard

et al. 2016

American Journal of Physiology-Heart and Circulatory Physiology

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“…Nevertheless, the appropriateness of the chosen stiffness limits is supported by the results in Fig. 2B, showing that the model predictions under stiffness perturbation are within the boundaries of independently measured data (7,35,44). Finally, all severity indexes have been compared under the same perturbation limits, making the comparison between indexes valid regardless of limits value.…”

Section: Indexes Representation Of Q Sendo /Q Nendomentioning

confidence: 68%

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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“…Therefore, FFR cannot be used as an independent index to assess microcirculation, since it is highly affected by the presence of an epicardial stenosis. However, in the absence of microvascular disease, it is possible to estimate FFR using only angiographic image data (41,42).…”

Section: H404 Assessment Of Coronary Microcirculation In a Swine Modelmentioning

confidence: 99%

Assessment of coronary microcirculation in a swine animal model

Zhang

Takarada

Molloi

2011

American Journal of Physiology-Heart and Circulatory Physiology

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Coronary microvascular dysfunction has important prognostic implications. Several hemodynamic indexes, such as coronary flow reserve (CFR), microvascular resistance, and zero-flow pressure (Pzf), were used to establish the most reliable index to assess coronary microcirculation. Fifteen swine were instrumented with a flow probe, and a pressure wire was advanced into the distal left anterior descending artery. Adenosine was used to produce maximum hyperemia. Microspheres were used to create microvascular dysfunction. An occluder was used to produce stenosis. Blood flow from the probe (Q p), aortic pressure, distal coronary pressure, and right atrium pressure were recorded. Angiographic flow (Q a) was calculated using a time-density curve. Flow probe-based CFR and angiographic CFR were calculated using Q p and Q a, respectively. Flow probe-based (NMRqh) and angiographic normalized microvascular resistance (NMRah) were determined using Q p and Q a, respectively, during hyperemia. Pzf was calculated using Q p and distal coronary pressure. Two series of receiver operating characteristic curves were generated: normal epicardial artery model (N model) and stenosis model (S model). The areas under the receiver operating characteristic curves for flow probe-based CFR, angiographic CFR, NMRqh, NMRah, and Pzf were 0. 855, 0.836, 0.976, 0.956, and 0.855 in N model and 0.737, 0.700, 0.935, 0.889, and 0.698 in S model. Both NMRqh and NMRah were significantly more reliable than CFR and Pzf in detecting the microvascular deterioration. Compared with CFR and Pzf, NMR provided a more accurate assessment of microcirculation. This improved accuracy was more prevalent when stenosis existed. Moreover, NMRah is potentially a less invasive method for assessing coronary microcirculation.angiography; blood flow; cardiovascular imaging; coronary microvascular function CORONARY ANGIOGRAPHY, a routine examination for patients with heart disease, provides an assessment of stenosis severity by visualizing the opacified arterial lumen. However, in many cases (12,40), the severity of myocardium ischemia correlates poorly with epicardial stenosis. Therefore, intracoronary physiological techniques have been developed to provide physiological evaluations for patients who undergo coronary angiography (8,34). Recently, the medical community's interest in coronary microcirculation has grown with the increasing awareness that microvascular dysfunction occurs in a number of myocardial disease states and has important prognostic implications (19,20). With this recognition comes the need for a method to accurately assess the functional capacity of coronary microcirculation for diagnostic purposes and to monitor the effects of therapeutic interventions targeted at reversing the extent of coronary microvascular dysfunction. To assess changes in the microcirculatory bed, several indexes have been proposed, such as coronary flow reserve (CFR), microvascular resistance (MR), and zero-flow pressure (P zf ). In the early 1990s, Gould et al. (14) introduced CFR...

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Quantification of fractional flow reserve based on angiographic image data

Cited by 23 publications

References 37 publications

Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume

Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume

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

Assessment of coronary microcirculation in a swine animal model

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