Allometric scaling in the coronary arterial system

American Journal of Physiology-Heart and Circulatory Physiology

2012

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Coronary flow reserve (CFR) and fractional flow reserve (FFR) are important physiological indexes for coronary disease. The purpose of this study was to validate the CFR and FFR measurement techniques using only angiographic image data. Fifteen swine were instrumented with an ultrasound flow probe on the left anterior descending artery (LAD). Microspheres were gradually injected into the LAD to create microvascular disruption. An occluder was used to produce stenosis. Contrast material injections were made into the left coronary artery during image acquisition. Volumetric blood flow from the flow probe (Q(q)) was continuously recorded. Angiography-based blood flow (Q(a)) was calculated by using a time-density curve based on the first-pass analysis technique. Flow probe-based CFR (CFR(q)) and angiography-based CFR (CFR(a)) were calculated as the ratio of hyperemic to baseline flow using Q(q) and Q(a), respectively. Relative angiographic FFR (relative FFR(a)) was calculated as the ratio of the normalized Q(a) in LAD to the left circumflex artery (LC(X)) during hyperemia. Flow probe-based FFR (FFR(q)) was measured from the ratio of hyperemic flow with and without disease. CFR(a) showed a strong correlation with the gold standard CFR(q) (CFR(a) = 0.91 CFR(q) + 0.30; r = 0.90; P < 0.0001). Relative FFR(a) correlated linearly with FFR(q) (relative FFR(a) = 0.86 FFR(q) + 0.05; r = 0.90; P < 0.0001). The quantification of CFR and relative FFR(a) using angiographic image data was validated in a swine model. This angiographic technique can potentially be used for coronary physiological assessment during routine cardiac catheterization.

Section: Protocolmentioning

confidence: 99%

Section: Advantages Of the Angiographic Measurement Based On Fpamentioning

confidence: 99%

Section: Advantages Of the Angiographic Measurement Based On Fpamentioning

confidence: 99%

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Quantification of absolute coronary flow reserve and relative fractional flow reserve in a swine animal model using angiographic image data

American Journal of Physiology-Heart and Circulatory Physiology

2012

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“…However, volumetric coronary blood flow and the calculated resistance are dependent on the arterial perfusion bed size. Previous reports (21,25) have shown that the arterial lumen volume is related to the myocardial mass and can be used to account for the dependent arterial bed size. Therefore, the normalized MR (NMR) (43) can be calculated as:…”

Section: Methodsmentioning

confidence: 99%

Assessment of coronary microcirculation in a swine animal model

American Journal of Physiology-Heart and Circulatory Physiology

2011

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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...

“…It is not possible to directly measure regional myocardial mass with angiography. However, it is possible to measure the dependent arterial lumen volume using densitometry (35), which can also be related to the myocardial mass (29,30). Therefore, arterial lumen volume can be used to account for the dependent arterial bed size.…”

Section: Protocolmentioning

confidence: 99%

Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation

American Journal of Physiology-Heart and Circulatory Physiology

2011

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Zhang Z, Takarada S, Molloi S. Quantification of coronary microvascular resistance using angiographic images for volumetric blood flow measurement: in vivo validation. Am J Physiol Heart Circ Physiol 300: H2096 -H2104, 2011. First published March 11, 2011 doi:10.1152/ajpheart.01123.2010.-Structural coronary microcirculation abnormalities are important prognostic determinants in clinical settings. However, an assessment of microvascular resistance (MR) requires a velocity wire. A first-pass distribution analysis technique to measure volumetric blood flow has been previously validated. The aim of this study was the in vivo validation of the MR measurement technique using first-pass distribution analysis. Twelve anesthetized swine were instrumented with a transit-time ultrasound flow probe on the proximal segment of the left anterior descending coronary artery (LAD). Microspheres were injected into the LAD to create a model of microvascular dysfunction. Adenosine (400 g·kg Ϫ1 ·min Ϫ1 ) was used to produce maximum hyperemia. A region of interest in the LAD arterial bed was drawn to generate time-density curves using angiographic images. Volumetric blood flow measurements (Q a) were made using a time-density curve and the assumption that blood was momentarily replaced with contrast agent during the injection. Blood flow from the flow probe (Qp), coronary pressure (Pa), and right atrium pressure (Pv) were continuously recorded. Flow probe-based normalized MR (NMRp) and angiography-based normalized MR (NMRa) were calculated using Qp and Qa, respectively. In 258 measurements, Qa showed a strong correlation with the gold standard Qp (Qa ϭ 0.90 Qp ϩ 6.6 ml/min, r 2 ϭ 0.91, P Ͻ 0.0001). NMRa correlated linearly with NMRp (NMRa ϭ 0.90 NMRp ϩ 0.02 mmHg·ml Ϫ1 ·min Ϫ1 , r 2 ϭ 0.91, P Ͻ 0.0001). Additionally, the BlandAltman analysis showed a close agreement between NMRa and NMRp. In conclusion, a technique based on angiographic image data for quantifying NMR was validated using a swine model. This study provides a method to measure NMR without using a velocity wire, which can potentially be used to evaluate microvascular conditions during coronary arteriography. coronary microvasculation CORONARY MICROVASCULAR DYSFUNCTION occurs in a number of myocardial disease states and has important prognostic implications in different clinical settings, including acute coronary syndromes, diabetic coronary disease, hypertrophic cardiomyopathy, and transplant cardiac allograft vasculopathy (25,26,39). Intracoronary physiological techniques have been advocated and several indexes for the assessment of changes in the microcirculatory bed have been proposed (2, 11, 51), such as coronary flow reserve (CFR) (9, 13, 34) and microvascular resistance (MR) (12,39,49). Many previous study findings suggest that MR is a useful variable for directly assessing microcirculatory function. In 1974, Gould et al. (19, 20, 21) postulated a hypothesis that minimum MR is independent of epicardial stenosis severity. Recently, Fearon and colleagues (1,7,12,14...