Comparison of Coronary Thermodilution and Doppler Velocity for Assessing Coronary Flow Reserve

Fearon, William F.; Farouque, H.M. Omar; Balsam, Leora B.; Cooke, David T.; Robbins, Robert C.; Fitzgerald, Peter J.; Yeung, Alan C.; Yock, Paul G.

doi:10.1161/01.cir.0000099521.31396.9d

Cited by 117 publications

(71 citation statements)

References 20 publications

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“…Under this condition, the velocity measured represents undisturbed blood velocity. This was supported by studies in coronary flow measurements using different methods by various groups (1,5,20,21). In studies of flow measurements with contrast dilution method, the data were collected in a 2-to 3-s time period, beginning at injection of contrast (20,21).…”

Section: Discussionmentioning

confidence: 96%

New method to measure coronary velocity and coronary flow reserve

Zhang¹,

Svendsen²,

Choy³

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

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Coronary flow reserve (CFR) is an important index of coronary microcirculatory function. The objective of this study was to validate the reproducibility and accuracy of intravascular conductance catheter-based method for measurements of baseline and hyperemic coronary flow velocity (and hence CFR). The absolute coronary blood velocity was determined by measuring the time of transit of a saline injection between two pairs of electrodes (known distance) on a conductance catheter during a routine saline injection without the need for reference flow. In vitro validation was made in the velocity range of 5 to 70 cm/s in reference to the volume collection method. In 10 swine, velocity measurements were compared with those from a flow probe in coronary arteries at different CFR attained by microsphere embolization. In vitro, the mean difference between the proposed method and volume collection was 0.7 Ϯ 1.34 cm/s for steady flow and Ϫ0.77 Ϯ 2.22 cm/s for pulsatile flow. The mean difference between duplicate measurements was 0 Ϯ 1.4 cm/s. In in vivo experiments, the flow (product of velocity and lumen cross-sectional area that is also measured by the conductance catheter) was determined in both normal and stenotic vessels and the mean difference between the proposed method and flow probe was Ϫ1 Ϯ 12 ml/min (flow ranged from 10 to 130 ml/min). For CFR, the mean difference between the two methods was 0.06 Ϯ 0.28 (range of 1 to 3). Our results demonstrate the reproducibility and accuracy of velocity and CFR measurements with a conductance catheter by use of a standard saline injection. The ability of the combined measurement of coronary lumen area (as previously validated) and current velocity and CFR measurements provides an integrative diagnostic tool for interventional cardiology.catheter; conductance ISCHEMIC HEART DISEASE is complex and often involves changes in epicardial coronary arteries and myocardial microvasculature. Coronary flow reserve (CFR, ratio of maximal to baseline flow) accounts for both epicardial and microvascular resistances (7). In the absence of epicardial artery disease, the CFR provides an index of the health of coronary microcirculation. Many patients who undergo percutaneous coronary interventions and revascularizations have low coronary flow because of both epicardial and microcirculatory disease (15,28).Several methods have been used for measuring velocity or blood flow rate in animals and humans. The intracoronary Doppler wire is a well-established method for determining blood flow velocity (3,11,19). The measurement relies on the detection of red blood cells moving past the ultrasound emitter/ receiver at the end of a guide wire. Although this method has been used clinically, it is angle dependent, and especially in disease vessels, it lacks the accuracy and reproducibility needed for a reliable diagnosis (17). The thermodilution method has also been proposed for determining blood velocity (24), but it has not garnered significant clinical utility because it requires a reference injection f...

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Section: Discussionmentioning

confidence: 96%

New method to measure coronary velocity and coronary flow reserve

Zhang¹,

Svendsen²,

Choy³

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

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“…Fearon et al 6, 11 further elucidated the usefulness of CFRthermo in open-chest porcine models. Using an ultrasonic flow probe placed around the proximal left anterior descending coronary artery (LAD) and a vascular occluder placed distal to the flow probe, the resting and hyperemic absolute coronary flow could be measured at baseline and after creation of an epicardial stenosis.…”

Section: Development Of Imr Theorymentioning

confidence: 99%

“…CFRthermo showed better correlation with the absolute coronary flow-derived CFR than the Doppler velocity-derived CFR, which further validated the thermodilution technique as a method of estimating coronary flow. 11 ecent studies have demonstrated the importance of the coronary microvasculature in various clinical settings and in the development of non-invasive tests for assessing it, including Doppler echocardiography, contrast echocardiography, cardiovascular magnetic resonance, and positron emission tomography. 1-4 However, conventional invasive parameters for assessing the microvasculature such as coronary flow reserve (CFR), Thrombolysis In Myocardial Infarction (TIMI) flow grade, corrected TIMI frame count, and TIMI myocardial perfusion grades 5 have important limitations, including their dependence on resting hemodynamics, semiquantitative nature, and lack of independence of the epicardial vessel.…”

Section: Development Of Imr Theorymentioning

confidence: 99%

Invasive Coronary Microcirculation Assessment

Kobayashi

Fearon

2014

Circ J

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The technological advance of the coronary pressure wire enabled simultaneous measurement of coronary artery pressure and coronary artery flow. With commercially available software, the pressure sensor of the wire acts as a distal thermistor, while the shaft of the wire serves as a proximal thermistor. In this manner, the mean transit time (Tmn) of room-temperature saline injected into a coronary artery can be determined from a thermodilution curve (Figure 1).De Bruyne and Pijls et al applied the thermodilution technique in an experimental model and found a strong correlation between the inverse of Tmn and absolute coronary flow. 9,10 They also showed that the thermodilution-derived coronary flow reserve (CFRthermo), defined as the resting mean transit time (TmnRest) divided by the hyperemic mean transit time (TmnHyp), correlated well with the standard CFR, both in their experimental model and in humans.Fearon et al 6,11 further elucidated the usefulness of CFRthermo in open-chest porcine models. Using an ultrasonic flow probe placed around the proximal left anterior descending coronary artery (LAD) and a vascular occluder placed distal to the flow probe, the resting and hyperemic absolute coronary flow could be measured at baseline and after creation of an epicardial stenosis. CFRthermo showed better correlation with the absolute coronary flow-derived CFR than the Doppler velocity-derived CFR, which further validated the thermodilution technique as a method of estimating coronary flow. 11 ecent studies have demonstrated the importance of the coronary microvasculature in various clinical settings and in the development of non-invasive tests for assessing it, including Doppler echocardiography, contrast echocardiography, cardiovascular magnetic resonance, and positron emission tomography. 1-4 However, conventional invasive parameters for assessing the microvasculature such as coronary flow reserve (CFR), Thrombolysis In Myocardial Infarction (TIMI) flow grade, corrected TIMI frame count, and TIMI myocardial perfusion grades 5 have important limitations, including their dependence on resting hemodynamics, semiquantitative nature, and lack of independence of the epicardial vessel. For these reasons, it became important to develop an invasive method for independently, quantitatively and reproducibly assessing the microvasculature, which is predictive of outcomes in various settings.Against this background and with the development of a thermodilution technique for estimating coronary flow while simultaneously measuring coronary pressure, the index of microcirculatory resistance (IMR) was first described just over 10 years ago. 6,7 This method enables investigation of the coronary microvasculature directly with high reproducibility and reliability in the cardiac catheterization laboratory where many patients in the USA first present for evaluation of their coronary circulation. 8 This review discusses the development of IMR, tips and tricks for its measurement, and its usefulness in various clinical settings. Assessmen...

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“…Quantitative assessment of CFR can be easily performed by intracoronary Doppler wires in the cardiac catheterization laboratory. However, the cutoff value for CFR is highly affected by epicardial stenosis and is very sensitive to hemodynamic changes (10,29). Fractional flow reserve (FFR) has been established as a useful physiological index of the severity of an epicardial stenosis in the catheterization laboratory.…”

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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Comparison of Coronary Thermodilution and Doppler Velocity for Assessing Coronary Flow Reserve

Abstract: Background-Thermodilution coronary flow reserve (CFR thermo

Cited by 117 publications

References 20 publications

New method to measure coronary velocity and coronary flow reserve

New method to measure coronary velocity and coronary flow reserve

Invasive Coronary Microcirculation Assessment

Assessment of coronary microcirculation in a swine animal model

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